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Background: Experiences of discrimination are a risk factor for subsequent cardiovascular disease. However, there is a lack of longitudinal research examining associations between discrimination and urinary catecholamines. This is surprising given the likely mediating role of sympathetic nervous system dysregulation in the association between psychosocial stress and cardiovascular morbidity., Purpose: The current study examined the 3 year longitudinal association between experiences of discrimination and urinary catecholamines., Methods: The sample included 149 college students (mean age at baseline = 18.8, standard deviation = 0.96; 45% Black/African American; 55% White/European American). Concentrations of epinephrine and norepinephrine-urinary catecholamines with established links to psychosocial stress exposure and subsequent morbidity-were determined from 12 hr overnight samples., Results: Results indicated that experiences of discrimination were associated with increases in both epinephrine (β = .284, standard error [SE] = .117, p = .015) and norepinephrine (β = .306, SE = .114, p = .001). These longitudinal associations persisted after adjusting for negative affect, depression, and rejection sensitivity and did not vary as a function of race/ethnicity., Conclusions: Results suggest that examination of overnight urinary catecholamines as a biological mediator of associations between experiences of discrimination and cardiovascular morbidity is warranted., (© Society of Behavioral Medicine 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Interindividual variability in 24-hour energy expenditure (24EE) during energy-balance conditions is mainly determined by differences in body composition and demographic factors. Previous studies suggested that 24EE might also be influenced by sympathetic nervous system activity via catecholamine (norepinephrine, epinephrine) secretion. Therefore, we analyzed the association between catecholamines and energy expenditure in 202 individuals from a heterogeneous population of mixed ethnicities., Methods: Participants (n = 202, 33% female, 14% black, 32% white, 41% Native American, 11% Hispanic, age: 36.9 ± 10.3 y [mean ± SD], percentage body fat: 30.3 ± 9.4) resided in a whole-room calorimeter over 24 hours during carefully controlled energy-balance conditions to measure 24EE and its components: sleeping metabolic rate (SMR), awake-fed thermogenesis (AFT), and spontaneous physical activity (SPA). Urine samples were collected, and 24-h urinary epinephrine and norepinephrine excretion rates were assessed by high-performance liquid chromatography., Results: Both catecholamines were associated with 24EE and SMR (norepinephrine: +27 and +19 kcal/d per 10 μg/24h; epinephrine: +18 and +10 kcal/d per 1 μg/24h) in separate analyses after adjustment for age, sex, ethnicity, fat mass, fat-free mass, calorimeter room, temperature, and physical activity. In a multivariate model including both norepinephrine and epinephrine, only norepinephrine was independently associated with both 24EE and SMR (both P < .008), whereas epinephrine became insignificant. Neither epinephrine nor norepinephrine were associated with adjusted AFT (both P = .37) but epinephrine was associated with adjusted SPA (+0.5% per 1 μg/24h)., Conclusions: Our data provide compelling evidence that sympathetic nervous system activity, mediated via norepinephrine, is a determinant of human energy expenditure during nonstressed, eucaloric conditions., (Published by Oxford University Press on behalf of the Endocrine Society 2020.)

Context: In healthy adults with detectable cold-induced brown adipose tissue activation (CIBA), the relationships between sympathetic nervous system (SNS) or thyroid activity during energy balance (EBL) with CIBA and body composition change are undetermined., Objective: To investigate the relationships between CIBA and thermoneutral catecholamines and thyroid hormones measured during EBL and to determine if CIBA, catecholamines, or thyroid hormones predict body composition changes., Design, Setting, Participants, and Interventions: Twelve healthy volunteers (seven male and five female) with positive CIBA [>2 standardized uptake value (g/mL)] had 24-hour energy expenditure (24hEE) assessed during EBL via whole-room indirect calorimetry while residing on a clinical research unit. Positron emission tomography/computed tomography scans were performed after exposure to 16°C for 2 hours to quantify CIBA., Main Outcome Measures: CIBA, 24hEE during EBL, and thermoneutrality with concomitant measurement of urinary catecholamines and plasma free T3 and free T4. Body composition at baseline and 6 months by dual-energy X-ray absorptiometry., Results: Lower urinary norepinephrine and free T4 were associated with higher CIBA (r = -0.65, P = 0.03; and r = -0.75, P < 0.01, respectively), but CIBA was not associated with 24hEE at thermoneutrality (P = 0.77). Lower CIBA (β = -3.5 kg/standardized uptake value; P < 0.01) predicted fat mass gain, whereas higher urinary norepinephrine and free T4 predicted future fat mass gain at 6 months (β = 3.0 kg per twofold difference in norepinephrine, P = 0.03; and β = 1.2 kg per 0.1-ng/dL difference in free T4, P = 0.03, respectively)., Conclusion: Lower SNS and free thyroid measurements at baseline indicate a greater capacity for CIBA, which may be predictive against fat mass gain.

Background: Hypertension is a major cause of heart failure. Excessive sympathoexcitation in patients with heart failure leads to poor prognosis. Since carotid body denervation (CBD) has been shown to reduce sympathetic nerve activity in animal models of hypertension and heart failure, we examined if bilateral CBD attenuates the progression of hypertensive heart failure and improves survival., Methods: We randomly allocated Dahl salt-sensitive rats fed a high-salt diet from 6 weeks of age into CBD (n = 31) and sham-operation (SHAM; n = 50) groups, and conducted CBD or SHAM at 7 weeks of age. We examined the time course of 24-hour urinary norepinephrine (uNE) excretion, blood pressure (BP) and the percent fractional shortening assessed by echocardiography, and estimated the pressure-natriuresis relationship at 14 weeks of age. Finally, we assessed hemodynamics, histological findings, and survival at 16 weeks of age., Results: Compared to SHAM, CBD significantly reduced 24-hour uNE at 12, 14, and 16 weeks of age, shifted the pressure-natriuresis relationship leftward without changing its slope, and attenuated the increase in BP. CBD preserved percent fractional shortening (34.2 ± 1.2 vs. 29.1 ± 1.3%, P < 0.01) and lowered left ventricular end-diastolic pressure (5.0 ± 0.9 vs. 9.0 ± 1.4 mm Hg, P < 0.05). Furthermore, CBD significantly attenuated myocardial hypertrophy (P < 0.01) and fibrosis (P < 0.01). Consequently, CBD markedly improved survival (relative risk reduction: 64.8%)., Conclusions: CBD attenuated the progression of hypertension and worsening of heart failure possibly through sympathoinhibition, and markedly improved survival in a rat model of hypertensive heart failure., (© American Journal of Hypertension, Ltd 2017. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

Background: Most currently available active antidepressant drugs are selective serotonin/noradrenaline reuptake inhibitors. However, as their clinical efficacy is not immediate, long-term administration is often accompanied by substantial side effects, and numerous patients remain non- or partial responders. We have recently found that the synthetic neurosteroid derivative 3β-methoxypregnenolone, which binds to the microtubule-associated protein-2, can provide a novel therapeutic approach in experimental model of depressive disorders in rats. To further validate the antidepressant-like efficacy of 3β-methoxypregnenolone, we investigated effects of a longer treatment (4-week oral administration; 50mg/kg/d) in a nonrodent species, the tree shrew, exposed to psychosocial stress that elicits close-to-human alterations observed in patients with depressive disorders., Methods: During the experimental period, physiological parameters were registered, including core body temperature and electroencephalogram, while animals were videotaped to analyze their avoidance behavior. Morning urine samples were collected for measurements of cortisol and noradrenaline levels., Results: We found that treatment with 3β-methoxypregnenolone abolished stress-triggered avoidance behavior and prevented hormone hypersecretion, hypothermia, and sleep disturbances, further suggesting its antidepressant-like efficacy. Comparative treatment with fluoxetine also prevented some of the physiological alterations, while the hypersecretion of cortisol and sleep disturbances were not or partially restored by fluoxetine, suggesting a better efficacy of 3β-methoxypregnenolone. Alpha-tubulin isoforms were measured in hippocampi: we found that 3β-methoxypregnenolone reversed the specific decrease in acetylation of α-tubulin induced by psychosocial stress, while it did not modify the psychosocial stress-elicited reduction of tyrosinated α-tubulin., Conclusions: Taken together, these data strongly suggest a potent antidepressant-like effect of 3β-methoxypregnenolone on translational parameters., (© The Author 2015. Published by Oxford University Press on behalf of CINP.)

Background: Rostral ventrolateral medulla (RVLM) plays a crucial role in the central regulation of cardiovascular functions. Cystathionine-β-synthase (CBS) is a major hydrogen sulfide (H2S)-generating enzyme that has been identified mainly in the brain. The present study was designed to examine CBS expression and determine its roles and mechanisms of regulating sympathetic outflow and blood pressure (BP) in the RVLM in spontaneously hypertensive rats (SHR)., Methods and Results: CBS expression was decreased in the RVLM in SHR compared to Wistar-Kyoto (WKY) rats. Accumulating evidences suggest that H2S interacts with nitric oxide (NO) to regulate cardiovascular function. Therefore, we hypothesize that the decrease in CBS expression in the RVLM may be involved in the disorder of l-arginine/NO pathway, which subsequently affects BP in SHR. Overexpression of CBS in the RVLM caused significant increases in BP, heart rate, and urinary norepinephrine excretion in SHR but not in WKY. Acute experiments were carried out at day 7 after gene transfer. NO metabolite levels, neuronal NO synthase, and γ-amino butyric acid were decreased in SHR after CBS gene transfer. Furthermore, pressor responses to microinjection of NG-monomethyl-l-arginine into RVLM were blunt in SHR transfected with AdCBS compared to SHR transfected with AdEGFP., Conclusions: Overexpression of CBS in the RVLM elicits enhanced pressor responses in SHR, but not in WKY, and the NO system is involved in these effects. The results suggest that alterations of H2S signaling in the brain may be associated with the development of hypertension., (© American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Hypertension is a powerful risk factor of atrial fibrillation (AF). The pathophysiology of AF with hypertension is associated with sympathoexcitation or the renin-angiotensin system; however, current therapies cannot sufficiently prevent its development. We previously revealed that brain angiotensin II type 1 receptor (AT1R) blockade causes a depressor response via sympathoinhibition. Herein, we evaluated whether brain AT1R contributes to AF development in hypertensive rats., Methods: We divided the stroke-prone spontaneously hypertensive rats (SHRSP) treated with intracerebroventricular (ICV) infusion of vehicle, ICV infusion of losartan (S-LOS), or oral administration of hydralazine (S-HYD); and Wistar Kyoto rats treated with ICV S-VEH., Results: Two weeks later, systolic blood pressure was significantly lower in the S-LOS group than in the S-VEH group and was even lower in the S-HYD group. Urinary norepinephrine excretion for 24h, an indirect marker of sympathoexcitation, significantly reduced in the S-LOS group but increased in the S-HYD group despite depressor response. AF was induced by transesophageal burst pacing. AF duration was significantly shorter in the S-LOS group than in the S-VEH group (5.0±0.4 vs. 15.2±3.7 s; n = 8 each; P < 0.05). However, it was significantly longer in the S-HYD group than in the S-VEH group. Interstitial atrial fibrosis and echocardiographic parameters did not differ between the SHRSP groups., Conclusions: Brain AT1R blockade suppresses AF inducibility and maintenance independent of depressor response in hypertensive rats., (© American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Context: Neuroendocrine and immune stresses imposed by chronic sleep restriction are known to be involved in the harmful cardiovascular effects associated with poor sleep., Objectives: Despite a well-known beneficial effect of napping on alertness, its effects on neuroendocrine stress and immune responses after sleep restriction are largely unknown., Design: This study was a strictly controlled (sleep-wake status, light environment, caloric intake), crossover, randomized design in continuously polysomnography-monitored subjects., Setting: The study was conducted in a laboratory-based study., Participants: The subjects were 11 healthy young men., Intervention: We investigated the effects on neuroendocrine and immune biomarkers of a night of sleep restricted to 2 h followed by a day without naps or with 30 minute morning and afternoon naps, both conditions followed by an ad libitum recovery night starting at 20:00., Main Outcome Measures: Salivary interleukin-6 and urinary catecholamines were assessed throughout the daytime study periods., Results: The increase in norepinephrine values seen at the end of the afternoon after the sleep-restricted night was not present when the subjects had the opportunity to take naps. Interleukin-6 changes observed after sleep deprivation were also normalized after napping. During the recovery day in the no-nap condition, there were increased levels of afternoon epinephrine and dopamine, which was not the case in the nap condition. A recovery night after napping was associated with a reduced amount of slow-wave sleep compared to after the no-nap condition., Conclusions: Our data suggest that napping has stress-releasing and immune effects. Napping could be easily applied in real settings as a countermeasure to the detrimental health consequences of sleep debt.

Patients with 22q11 deletion syndrome (22q11DS) have a high prevalence of psychiatric disorders and intellectual disability. At present the neurobiology underlying psychopathology in 22q11DS is still not understood. In the present study, we analyzed urinary serotonergic, dopaminergic and noradrenergic markers in 67 adults with 22q11DS. Levels of serotonin and the catecholamine metabolite homovanillic acid were significantly lower in the 22q11DS subjects compared to healthy controls. Within the 22q11DS group, levels of dopamine, homovanillic acid, norepinephrine, vanillyl mandelic acid and serotonin positively correlated with Full Scale Intelligence Quotient scores. Our results suggest that cognitive deficits in 22q11DS are associated with abnormal function of several neurotransmitters.

Background: Angiotensin II type 1 receptor (AT1R) blockers have various benefits on hypertension and/or heart failure. We demonstrated that telmisartan (TLM), an AT1R blocker, causes sympathoinhibition by reduction of reactive oxygen species (ROS) in the rostral ventrolateral medulla (RVLM) of stroke-prone spontaneously hypertensive rats (SHRSPs). The aim of this study was to determine whether TLM improves survival in rats with hypertension and heart failure., Methods: Angiotensin II-infused and salt-loaded SHRSPs were divided into TLM-treated, candesartan cilexetil (CAN)-treated, and control groups. We determined the dose of TLM or CAN with similar depressor effects. We examined survival, urinary norepinephrine excretion (uNE) as a parameter of sympathoexcitation, ROS in the RVLM, and left ventricular (LV) end-diastolic pressure (LVEDP). LV hypertrophy (LVH) was assessed by echocardiography and heart/body weight., Results: Compared with the control group, TLM improved survival to a greater extent than CAN. At 4 weeks after treatment, ROS in the RVLM and uNE were significantly lower in the TLM-treated group than in the CAN-treated group, despite the similar depressor effects. At 8 weeks after the treatments, LVH and LVEDP were attenuated in the TLM-treated group compared with the CAN-treated group., Conclusions: Our results suggest that TLM has the potential to reduce mortality, LVH, and LVEDP and that enhanced sympathoinhibition by reduction of ROS in the RVLM might be one of the mechanisms contributing to the beneficial actions of TLM in a model of rats with severe hypertension and heart failure.

Background: We recently reported that activation of neuregulin-1 (NRG-1)/ErbB signaling in the rostral ventrolateral medulla (RVLM) of the brainstem elicits sympathoinhibition and depressor effects, and ErbB2-type ErbB receptors are involved in the neurogenic mechanisms of hypertension. Nitric oxide (NO) in the RVLM also elicits sympathoinhibition and depressor effects. NRG-1 enhances NO synthase (NOS) expression in several tissues. Here, we tested the hypothesis that ErbB2 inhibition in the RVLM contributes to increasing blood pressure via modulating the effects of NOS., Methods: We measured the effects of chronic intracisternal infusion of an ErbB2 antagonist and local ErbB2 inhibition in the RVLM using RNA interference (ErbB2 siRNA) on blood pressure (BP), heart rate (HR), norepinephrine excretion (uNE), and NOS expression in the RVLM. The central effects of the ErbB2 antagonist or NRG-1β were investigated with or without chronic and acute prior administration of a NOS inhibitor., Results: Intracisternal infusion of the ErbB2 antagonist and ErbB2 siRNA increased BP, HR, and uNE; and reduced neuronal and endothelial NOS expression in the RVLM. Further, prior systemic administration of a NOS inhibitor abolished the pressor response to intracisternal infusion of an ErbB2 antagonist in awake rats. Prior injection of a NOS inhibitor or γ-aminobutyric acid-A receptor antagonist into the RVLM attenuated the depressor response to NRG-1 in anesthetized rats., Conclusions: These findings indicate that inhibition of ErbB2 expression in the RVLM leads to hypertension, at least in part, by reducing NO synthesis and inhibiting γ-aminobutyric acid activity. NRG-1/ErbB signaling in the RVLM might exist upstream of NO synthesis.

Study Objectives: Sleep disordered breathing (SDB) occurs at an increased incidence in children with Down Syndrome (DS) compared to the general pediatric population. We hypothesized that, compared with typically developing (TD) children with SDB, children with DS have a reduced cardiovascular response with delayed reoxygenation after obstructive respiratory events, and reduced sympathetic drive, providing a potential explanation for their increased risk of pulmonary hypertension., Design: Beat-by-beat heart rate (HR) was analyzed over the course of obstructive events (pre, early, late, post-event) and compared between groups. Also compared were the time for oxygen resaturation post-event and overnight urinary catecholamines., Setting: Pediatric sleep laboratory., Patients: Sixty-four children aged 2-17 y referred for investigation of SDB (32 DS; 32 TD) matched for age and obstructive apnea/hypopnea index., Measurement and Results: Children underwent overnight polysomnography with overnight urine collection. Compared to TD children, those with DS had significantly reduced HR changes post-event during NREM (DS: 21.4% ± 1.8%, TD: 26.6% ± 1.6%, change from late to post-event, P < 0.05). The time to resaturation post-event was significantly increased in the DS group (P < 0.05 for both NREM and REM sleep). Children with DS had significantly reduced overnight urinary noradrenaline (P < 0.01), adrenaline (P < 0.05) and dopamine levels (P < 0.01) compared with TD children., Conclusion: Children with DS and SDB exhibit a compromised acute cardio-respiratory response and dampened sympathetic response to SDB compared with TD children with SDB. These data may reflect autonomic dysfunction in children with DS that may place them at increased risk for cardiovascular complications such as pulmonary hypertension.

Background: Glomerular hyperfiltration predicts development of nephropathy in hypertension but the factors responsible for increased glomerular filtration rate (GFR) are not well known. Aim of this study was to examine which clinical variables influence GFR in the early stage of hypertension., Methods: Participants were 1,106 young-to-middle-age hypertensive adults with creatinine clearance >60 ml/min/1.73 m(2). Clinic and ambulatory blood pressures (BPs) were measured and the difference between clinic and 24-h systolic BP was defined as the white-coat effect (WCE). In 606 participants, 24-h urinary epinephrine and norepinephrine were also measured. Glomerular hyperfiltration, defined as a GFR ≥150 ml/min/1.73 m(2), was present in 201 subjects., Results: Patients' mean age was 33.1 ± 8.5 years and office BP was 146 ± 10.5/94 ± 5.0 mm Hg. In multivariable linear regression, significant predictors of GFR were younger age (P < 0.0001), male gender (P < 0.0001), 24-h systolic BP (P = 0.0001), body mass (P < 0.0001), WCE (P = 0.02), log-epinephrine (P = 0.01), and coffee use (P < 0.01). In a logistic model, independent predictors of glomerular hyperfiltration were obesity (odds ratio, 95% confidence interval = 6.1, 3.8-9.8), male gender (2.9, 1.8-4.9), age <33 years (2.1, 1.5-3.1), ambulatory hypertension (2.0, 1.4-3.0), WCE >15 mm Hg (1.6, 1.1-2.3), heavy coffee use (2.0, 1.1-3.8), and epinephrine >25 mcg/24 h (1.9, 1.2-3.1)., Conclusions: The novel finding of this study is that hyper-reactivity to stress, as determined by urinary epinephrine level and WCE, and coffee use contribute to determining glomerular hyperfiltration in the early stage of hypertension. Our data may help to identify a subset of patients with glomerular hyperfiltration, who may be at increased risk of chronic kidney disease and may benefit from antihypertensive treatment.

Background: We have previously documented the finding that central angiotensin type 2 receptors (AT2R) negatively modulate sympathetic outflow and arterial blood pressure (BP). In this study, we investigated the effects of intracerebroventricular (icv) infusion of Compound 21 (C21), the first selective nonpeptide AT2R agonist, on norepinephrine (NE) excretion and BP in rats., Methods: C21 was infused icv for 7 days, using a micro-osmotic pump. Urinary NE concentration was measured using the NE enzyme immunoassay kit. BP was recorded by radiotelemetry. After 7 days, the rats were killed and three relevant samples from sympathetic brain regions and the cerebral cortex were obtained by micro-punching to measure neuronal nitric oxide synthase (nNOS) protein expression by western blot. In addition, the influence of C21 on neuronal potassium current (I(Kv)) was determined by whole-cell patch-clamp in a neuron cell line, CATH.a., Results: (i) Icv treatment with C21 significantly decreased both the concentration and the amount of NE in night time urine, but had no effect on daytime urine. (ii) C21-treated rats exhibited a slight but significant decrease in BP. (iii) The effects of C21 on NE excretion and BP were abolished by use of the AT2R antagonist, PD123319, and nitric oxide synthase (NOS) inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME). (iv) C21 treatment significantly upregulated nNOS expression in the paraventricular nucleus of the hypothalamus (PVN) and rostral ventrolateral medulla (RVLM), but not in the nucleus of the solitary tract (NTS) and cerebral cortex. (v) In CATH.a neurons, C21 treatment significantly increased I(Kv), and this increase was completely abolished by PD123319 and L-NAME., Conclusions: These results demonstrate a central inhibitory influence of C21 on sympathetic outflow by means of a nNOS-dependent mechanism that might be mediated by facilitating the neuronal potassium channel.

Context: Recently, brown adipose tissue (BAT) gained interest as a possible target for cold-induced thermogenesis, and therefore a target for treatment of obesity in adult humans. However, mitochondrial uncoupling takes place not only in BAT but also in skeletal muscle tissue. Both tissues may be involved in cold-induced thermogenesis, which is presumably regulated by the sympathetic nervous system., Objective: Here we studied whether blockade of β-adrenergic receptors using propranolol diminishes cold-induced thermogenesis and mitochondrial uncoupling in skeletal muscle tissue., Design: Ten lean subjects participated in this study and stayed twice (control and β-blockade using propranolol) for 84 h in a respiration chamber-the first 36 h for baseline measurements, followed by 48 h of mild cold exposure (16 C). Energy expenditure was measured continuously. After 36 and 84 h, muscle biopsies were taken in which mitochondrial uncoupling was studied., Results: Energy expenditure increased upon mild cold exposure (+5.0 ± 1.2 W; P < 0.005), i.e. cold-induced thermogenesis. However, contrary to our hypothesis, this cold-induced thermogenesis was not diminished after β-blockade (+4.7 ± 2.1 W for blockade vs. +5.1 ± 1.4 W for control; P = 0.59 for interaction cold blockade). Skeletal muscle mitochondrial uncoupling was significantly related to cold-induced thermogenesis in the control situation (R(2) = 0.650; P < 0.01). There was no such relation during β-blockade., Conclusions: Our results suggest that skeletal muscle mitochondrial uncoupling may be involved in cold-induced thermogenesis and that this may be regulated by β(2)-receptors. When the β(1)- and β(2)-receptors are blocked, a β(3)-regulated process like mitochondrial uncoupling in BAT might take over the role of skeletal muscle mitochondrial uncoupling.

Objective: Resting energy expenditure (EE) is a major contributor to the total EE and thus plays an important role in body weight regulation. Adaptive thermogenesis is a major component of EE in rodents, but little is known on the effects of exposure of humans to mild and sustainable reduction in environmental temperature., Design: To characterize the dynamic changes in continuously measured resting EE, substrate utilization, and hormonal axes simultaneously in response to mild reduction in environmental temperature, we performed a cross-over intervention., Methods: Twenty-five volunteers underwent two 12-h recordings of EE in whole room indirect calorimeters at 24 and 19 °C with simultaneous measurement of spontaneous movements and hormonal axes., Results: Exposure to 19 °C resulted in an increase in plasma and urine norepinephrine levels (P<0.0001), and a 5.96% (P<0.001) increase in EE without significant changes in spontaneous physical activity. Exposure to the lower temperature resulted in a significant increase in free fatty acid levels (P<0.01), fasting insulin levels (P<0.05), and a marginal decrease in postprandial glucose levels. A small but significant (P<0.002) increase in serum free thyroxine and urinary free cortisol (P<0.05) was observed at 19 °C., Conclusions: Our observations indicate that exposure to 19 °C, a mild and tolerable cold temperature, results in a predictable increase in EE driven by a sustained rise in catecholamine and the activation of counter-regulatory mechanisms.

The physiological implication of C-type natriuretic peptide (CNP) including energy metabolism has not been elucidated, because of markedly short stature in CNP-null mice. In the present study we analyzed food intake and energy expenditure of CNP-null mice with chondrocyte-targeted CNP expression (CNP-Tg/Nppc(-/-) mice), in which marked skeletal dysplasia was rescued, to investigate the significance of CNP under minimal influences of skeletal phenotypes. In CNP-Tg/Nppc(-/-) mice, body weight and body fat ratio were reduced by 24% and 32%, respectively, at 20 wk of age, and decreases of blood glucose levels during insulin tolerance tests were 2-fold exaggerated at 17 wk of age, as compared with CNP-Tg/Nppc(+/+) mice. Urinary noradrenalin excretion of CNP-Tg/Nppc(-/-) mice was greater than that of CNP-Tg/Nppc(+/+) mice by 28%. In CNP-Tg/Nppc(-/-) mice, rectal temperature at 1600 h was higher by 1.1 C, and uncoupling protein-1 mRNA expression in the brown adipose tissue was 2-fold increased, which was canceled by propranolol administration, as compared with CNP-Tg/Nppc(+/+) mice. Oxygen consumption was significantly increased in CNP-Tg/Nppc(-/-) mice compared with that in CNP-Tg/Nppc(+/+) mice. Food intake of CNP-Tg/Nppc(-/-) mice upon ad libitum feeding and refeeding after 48 h starvation were reduced by 21% and 61%, respectively, as compared with CNP-Tg/Nppc(+/+) mice. This study unveiled a new aspect of CNP as a molecule regulating food intake and energy expenditure. Further analyses on precise mechanisms of CNP actions would lead to the better understanding of the significance of the CNP/guanylyl cyclase-B system in food intake and energy expenditure.

Context: The biochemical diagnosis of pheochromocytoma depends on the demonstration of elevated levels of catecholamines (i.e. epinephrine, norepinephrine, and dopamine) and their metabolites., Objective: The aim of the study was to determine the preanalytical influence of a catecholamine-rich diet on urinary free and deconjugated catecholamines in healthy volunteers with a highly specific and sensitive analytical technique., Design, Setting, and Participants: We conducted a crossover study involving 27 healthy adults in a specialist medical center., Interventions: Subjects consumed catecholamine-rich nuts and fruits at fixed times on one day (about 35 micromol dopamine and 1 micromol norepinephrine) and catecholamine-poor products on another day. Urine samples were collected at timed intervals before, during, and after experimental and control interventions., Main Outcome Measures: We performed automated online sample preparation coupled to isotope-dilution mass spectrometry measurements of urinary concentrations of free and deconjugated catecholamines., Results: The catecholamine-rich diet had substantial effects on urinary excretions of deconjugated dopamine (up to 20-fold increases) and norepinephrine (up to 10-fold). Dietary catecholamines had less but significant effects on urinary excretion of free dopamine and norepinephrine (up to 1.5-fold increases). Outputs of urinary free and deconjugated epinephrine remained unaffected., Conclusions: Urinary excretion of deconjugated norepinephrine and dopamine is strongly affected by consumption of catecholamine-rich food products, thereby increasing the likelihood of a false-positive test result during hormonal evaluation for pheochromocytoma. Measurement of deconjugated catecholamines should therefore preferably be avoided, in favor of measurement of urinary free catecholamines. In case of demonstrating increased urinary excretion of deconjugated norepinephrine and dopamine, repeated measurements are warranted with dietary restrictions prior to sample collection.

Included in the Cooperative Cope Thunder exercises from Japan to Alaska is one of the longest distance flight missions carried out by Japan Air-Self Defense Force F-15 pilots. The magnitude of the flight stress of these pilots is considered to be quite high. The purpose of this study was to evaluate the flight stress induced by the long-distance flights. The subjects were eight pilots who participated on a volunteer basis. Samples of urine were collected approximately 30 minutes before (preflight) and 20 minutes after (postflight) the flights. The ratios (post-:preflight) of noradrenaline levels were 1.20 +/- 0.09 (Japan-Alaska) and 1.32 +/- 0.12 (Alaska-Japan), and those of adrenaline were 4.03 +/- 1.06 and 3.68 +/- 0.98. These results strongly suggest that psychological stress during the long-distance flights is increased in the fighter pilots.

We identified an effect of gamma-glutamylethylamide (theanine) on feeding in a rat study. Oral theanine suppressed the food intake of rats. The serum glucose level did not differ from the control, but the insulin concentration was reduced and the corticosterone concentration was increased by theanine. We suggest that the effect of theanine on feeding involved hormones.

Context: Chronic pain has been associated with elevated cortisol, reduced LH and testosterone (T), and/or augmented circulating or excreted catecholamines. Most endocrine studies have been conducted in patients in whom the potentially confounding effects of depression, inflammatory disease, or coexistent medication use have not been controlled., Objective: The objective of the study was to test the hypothesis that chronic pain activates ACTH-cortisol and suppresses LH-T., Design and Setting: This was a case control study conducted at a clinical research center., Participants: Participants included 16 opioid-naive men with chronic osteoarthritis pain, aged 35-65 yr with body mass index 20-30 kg/m2, and 12 healthy, opioid- and pain-free men of similar ages and body mass indexes., Methods: We compared circulating concentrations of ACTH, cortisol, LH, and T derived from every 20-min blood sampling (2000-0800 h), and 24-h urinary excretion of cortisol, epinephrine, norepinephrine, and dopamine., Results: There were no significant differences in mean or integrated concentrations of ACTH, cortisol, LH, or T, or in the corresponding approximate entropy scores in osteoarthritis patients, compared with control subjects. The 0800-h serum LH concentrations were elevated in patients vs. controls (6.42 +/- 1.65 vs. 3.99 +/- 1.54 IU/liter, mean +/- sd, P = 0.02), whereas there were no significant group differences in total or free T, SHBG, cortisol binding globulin, dehydroepiandrosterone sulfate, or urinary cortisol and catecholamines., Conclusions: These data suggest that neuroendocrine function is not significantly altered in otherwise healthy men with chronic musculoskeletal pain and that prior reports of such hormonal abnormalities may have resulted from the confounding effects of coexistent illness or medication use.

Context: Leptin release is regulated by factors other than fat mass alone. Previous observations provide indirect evidence for an inhibitory effect of dopaminergic neurotransmission on leptin secretion. This study was done to establish the effect of bromocriptine treatment on circadian plasma leptin concentrations in obese humans., Objective: The objective of the study was to study the acute effects of bromocriptine (a D2R agonist) on circadian leptin levels in obese women, whereas body weight and caloric intake remained constant., Design: This was a prospective, single-blind, crossover study (2004)., Setting: The study was conducted at a clinical research center., Participants: Eighteen healthy obese women (body mass index 33.2 +/- 0.6 kg/m(2)) were studied twice in the early follicular phase of their menstrual cycle., Intervention(s): Treatment consisted of bromocriptine or placebo for 8 d., Main Outcome Measure(s): Blood was collected during 24 h at 20-min intervals for determination of leptin concentrations at the last day of medical treatment (bromocriptine or placebo). Mean 24-h serum concentrations were determined for insulin, glucose, free fatty acids, and triglycerides., Results: Short-term treatment with bromocriptine reduced leptin concentration (placebo 33.6 +/- 2.5 vs. bromocriptine 30.5 +/- 2.5 ng/liter, P = 0.03). Free fatty acid concentrations were increased by treatment with bromocriptine. The increase of free fatty acids was inversely related with the decline of leptin levels. The decline of glucose, insulin, or prolactin concentrations in response to bromocriptine was not correlated with the reduction of leptin., Conclusion: Activation of dopamine D2 receptors by bromocriptine lowers circulating leptin levels in obese women, which suggests that dopaminergic neurotransmission is involved in the control of leptin release in humans.

Objectives: Emotion regulation is hypothesized to be related to health through neuroendocrine-immune changes. This study examined the role of the neuroendocrine variables 24-h urinary cortisol and noradrenaline, and the immune variable serum interleukin 6 as mediators between emotion regulation styles and health (perceived health and disease activity: erythrocyte sedimentation rate (ESR) and Thompson joint score)., Methods: Sixty patients with rheumatoid arthritis (mean age 59.0+/-11.2 yr; 38 female) participated., Results: Emotion regulation was not associated with immune functioning or disease activity, but it was somewhat related to neuroendocrine functioning: one of the emotion regulation styles, ambiguity, was related to noradrenaline in women (r = 0.39) but not in men. The indicators of neuroendocrine functioning (cortisol and noradrenaline) were correlated (r = 0.40), as were indicators of immune functioning (interleukin 6) and inflammatory activity (ESR; r = 0.53), but analyses did not indicate a role of these physiological variables in mediating between emotion regulation and health: neuroendocrine variables were not related to interleukin 6 or ESR, and none of the physiological parameters was correlated with joint score or perceived health., Conclusions: To examine whether the proposed mediational processes apply to individual patients, a longitudinal within-subjects design is needed. In our cross-sectional study, emotion regulation was somewhat related to neuroendocrine functioning, but our study did not uncover a potential mediational role of cortisol, noradrenaline or interleukin 6 in the relationship between emotion regulation and health in rheumatoid arthritis.

Background: Hypertension is one of the main side-effects of long-term therapy with ciclosporin. However, the influence of salt intake on the 24-h mean blood pressure of patients with psoriasis treated with ciclosporin is not known., Objectives: To evaluate, in patients with psoriasis, the sodium sensitivity of the ciclosporin-induced rise in blood pressure., Methods: The 24-h ambulatory blood pressure was evaluated in 13 patients with psoriasis (age range 20-57 years) in two phases, before (phase I) and after the completion of 4 months of therapy with ciclosporin 3 mg kg(-1) daily (phase II). In both phases, the patients were studied in conditions of low sodium (LS) intake followed by a high sodium (HS) diet., Results: Twenty-four-hour mean +/- SD blood pressure during LS and HS intake was, respectively, 86.3 +/- 1.6 mmHg and 85.5 +/- 1.8 mmHg during phase I, and 88.5 +/- 1.5 mmHg and 91.8 +/- 2.2 mmHg (P < 0.001 vs. phase I, HS; P < 0.05 vs. phase II, LS) during phase II. The median (interquartile range) sodium sensitivity index was greater during phase II than during phase I: - 0.0028 (- 0.0071 to 0.0009) vs. 0.0065 (- 0.0055 to 0.0258) (P < 0.02). The plasma levels and the daily urinary excretion of noradrenaline did not differ between phases I and II., Conclusions: The ciclosporin-induced rise in blood pressure is sodium sensitive. It is also suggested that sympathetic activation is not involved in the pathogenesis of ciclosporin-induced rise in blood pressure.

Tinuvin 770 [bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate], is a UV light stabilizer plastic additive used worldwide. It is a component of many plastic materials used in medical and food industries. Earlier studies demonstrated its in vitro L-type Ca2+ channel and nicotinic acetylcholine receptor blocking properties. Our previous experiments have proved the toxic effects of Tinuvin 770 on isolated rat cardiomyocytes. The present study investigates the cardiotoxic effects of Tinuvin 770 in vivo. Wistar rats were intraperitoneally injected with increasing doses of Tinuvin 770 (1, 10, 100 microg, and 1 mg) 15 times during a 5-week period. Myocardial samples were analyzed by light, electron, and fluorescent microscopy. The lead-acetate method was used to detect intracellular Ca2+, and glyoxylic acid technique to assess alteration in adrenergic innervation. Focal myocytolysis and hypercontraction necrosis could be observed in rats treated with higher doses of Tinuvin 770. In these groups, intracellular Ca2+ accumulation and increased catecholamine release were detected. Tinuvin 770 not only displays L-type Ca2+ channel blocking properties, but can also lead to catecholamine release, similar to effects of the first generation of L-type Ca2+ channel blockers. Morphological results correspond to catecholamine-induced myocardial damage. Current literature, as well as our study, indicates that more detailed toxicological analysis of Tinuvin 770 should be required, and current regulations in medical and food industries should adopt the new results.

Despite pituitary hormone replacement, patients with craniopharyngioma often complain of fatigue. They may have deficient control of catecholamine secretion caused by hypothalamic lesion. Another hypothesis is a functional defect in catecholamine production through either glucocorticoid deficiency because high intraadrenal glucocorticoid concentration is necessary for epinephrine synthesis or unrecognized hypoglycemia, which can intrinsically alter epinephrine secretion. We measured catecholamine response to insulin-induced hypoglycemia and orthostasis, and 24-h urinary catecholamine excretion, in 16 children with craniopharyngioma (patients) and 27 sex- and age-matched short children. We also studied the influence of a 4-fold increase in the usual daily dose of hydrocortisone on catecholamine excretion (50 vs. 12 mg/m(2) of body surface area) in the glucocorticoid-deficient patients. Last, we compared 24-h continuous sc glucose in patients and 10 sex- and age-matched healthy children. The results are expressed as medians (25th, 75th). For a similar blood glucose nadir after insulin administration, peak plasma epinephrine in response to hypoglycemia was lower in patients vs. controls [420 (120, 715) vs. 730 (460, 1200) ng/liter, P < 0.01], whereas peak plasma norepinephrine was higher [390 (280, 550) vs. 270 (180, 280) ng/liter, P < 0.05]. Catecholamine response to orthostasis did not differ between groups. Urinary epinephrine was significantly lower in patients (P < 0.001), whereas urinary norepinephrine was similar. The extent of epinephrine deficiency correlated with neither tumor size nor hypothalamic involvement. A 4-fold higher hydrocortisone dose did not correct the defective epinephrine excretion in the glucocorticoid-deficient patients. Last, the 24-h sc glucose values were similar between patients and controls. In conclusion, children with craniopharyngioma have a defect in epinephrine but not norepinephrine production. There is no proof of a univocal origin, either organic or functional. Whether abnormal catecholamine secretion alters glucose level during fasting or acute illness, or hampers adaptation to exercise, requires further studies.

Background: Dopamine D(2) receptors (D(2)Rs) are expressed in the kidney. It has not been determined whether D(2)Rs are involved in the mechanism of sodium handling and blood pressure (BP) control., Methods: The function of D(2)Rs was investigated in mice disrupted with D(2)R gene (D(2)KO mice). Six-week-old male D(2)KO mice and wild-type (WT) mice were fed high-salt (4% NaCl) or low-salt (0.01% NaCl) diets for 8 weeks., Results: Before starting the metabolic diet, there were no significant differences in body weight, food consumption, and 24-h urine excretions of creatinine, sodium and potassium. The high-salt diet caused a significant elevation in systolic BP in D(2)KO mice but not in WT mice. Calculation of sodium and potassium balances revealed a significantly high level of sodium retention in D(2)KO mice placed on the high-salt diet. Twenty-four-hour urine norepinephrine excretions and heart rates, indicators of sympathetic activity, were not different in D(2)KO and WT mice on the high-salt diet. Administration of nemonapride, a specific D(2)-like receptor antagonist, to WT mice given 0.9% NaCl in drinking water caused suppression of urinary sodium excretion but had no effect in mice without salt loading., Conclusions: These results suggest that D(2) receptors promote sodium excretion during a period of high salt intake. A defect in this mechanism may result in sodium-dependent BP elevation.

Measurements of plasma normetanephrine and metanephrine provide a highly sensitive test for diagnosis of pheochromocytoma, but false-positive results remain a problem. We therefore assessed medication-associated false-positive results and use of supplementary tests, including plasma normetanephrine responses to clonidine, to distinguish true- from false-positive results. The study included 208 patients with pheochromocytoma and 648 patients in whom pheochromocytoma was excluded. Clonidine-suppression tests were carried out in 48 patients with and 49 patients without the tumor. Tricyclic antidepressants and phenoxybenzamine accounted for 41% of false-positive elevations of plasma normetanephrine and 44-45% those of plasma and urinary norepinephrine. High plasma normetanephrine to norepinephrine or metanephrine to epinephrine ratios were strongly predictive of pheochromocytoma. Lack of decrease and elevated plasma levels of norepinephrine or normetanephrine after clonidine also confirmed pheochromocytoma with high specificity. However, 16 of 48 patients with pheochromocytoma had normal levels or decreases of norepinephrine after clonidine. In contrast, plasma normetanephrine remained elevated in all but 2 patients, indicating more reliable diagnosis using normetanephrine than norepinephrine responses to clonidine. Thus, in patients with suspected pheochromocytoma and positive biochemical results, false-positive elevations due to medications should first be eliminated. Patterns of biochemical test results and responses of plasma normetanephrine to clonidine can then help distinguish true- from false-positive results.

Background: Impairment of renal dopamine excretion on high-salt diet (HS) may account for increased blood pressure (BP) in hypertensive subjects. Whether such impairment of dopaminergic activity exists in the adrenal gland is unknown. The purpose of this study was to differentiate degrees of dopaminergic inhibition of aldosterone secretion in patients with aldosterone-producing adenoma (APA)., Methods: A total of 15 patients with unilateral APA were fed a low-salt diet (LS) for 1 week, followed by another week on HS. At the end of each diet period, 24-h ambulatory BP recording, daily urine catecholamine measurement, and a metoclopramide test were performed., Results: A high-salt diet increased both daytime and nighttime BP (P < .001), and urine dopamine excretion (P < .01). Intravenous injection of 10-mg metoclopramide increased plasma aldosterone concentrations (PAC) on both diets. The areas-under-the-curve for PAC between LS and HS were not different, but the area-under-the-curve for PAC increment was greater on HS (P < .05). Six patients with increment areas on HS greater than those on LS by 50% were termed "suppressible," and the remainders as "nonsuppressible." On HS, the so-called suppressible subjects had greater urine dopamine and less urine norepinephrine excretions (P < .05). The nonsuppressible subjects had greater percentage increase of nighttime BP by HS than the suppressible (for systolic BP, 13.1% v 4.5%, P < .01; for mean BP, 12.0% v 5.1%, P < .01, respectively), but no difference in daytime BP., Conclusions: Two subtypes of APA were defined according to their responses to metoclopramide during salt manipulation. On HS, the nonsuppressible subjects, with less dopaminergic inhibition of aldosterone secretion, had less urinary DA excretion and greater BP elevation. The renal and adrenal dopaminergic activities are regulated in a parallel fashion.

Measurements of plasma free metanephrines, normetanephrine (NMN) and metanephrine (MN), provide a sensitive test for diagnosis of pheochromocytoma in adults but have not been evaluated in children. We therefore established reference ranges for plasma and urinary metanephrines and the catecholamines, norepinephrine (NE) and epinephrine (E), in 86 healthy children (age 5-17). A group of 158 healthy adults (age 18-72) served as a comparison group. Pediatric reference ranges were applied to examine the diagnostic utility of the various tests in 45 children evaluated for pheochromocytoma (age 8-17; 38 with von Hippel-Lindau syndrome), with tumors found on 12 occasions. Upper reference limits for E and MN were higher and those for NE and NMN lower in children than in adults. Boys had higher plasma levels of E and MN and higher urinary excretion of all four amines than girls. Plasma free metanephrines provided a diagnostic test with values for sensitivity (100%) and specificity (94%) that were equal to or higher than those of other tests. In two children screened for pheochromocytoma on multiple occasions, use of pediatric reference ranges for plasma free metanephrines indicated the tumor a year earlier than indicated using adult reference ranges. The findings indicate that plasma free metanephrines provide a sensitive tool for detection of pheochromocytoma in children. Age appropriate reference ranges should be used and gender differences should be considered.

Although sodium retention and volume expansion occur during GH administration, blood pressure is decreased or unchanged. The aim was to study the effect of short- and long-term GH replacement in adults on sodium balance, renal hemodynamics, and blood pressure. Ten adults with severe GH deficiency were included into a 7-d, randomized, placebo-controlled, cross-over trial followed by 12 months of open GH replacement. All measurements were performed under metabolic ward conditions. Extracellular water (ECW) was determined using multifrequency bioelectrical impedance analysis. Renal plasma flow and glomerular filtration rate were assessed using renal paraminohippurate and Cr(51) EDTA clearances, respectively. Renal tubular sodium reabsorption was assessed using lithium clearance. Plasma renin activity (PRA), plasma concentrations of angiotensin II, aldosterone, atrial natriuretic peptides and brain natriuretic peptides (BNP) and 24-h urinary norepinephrine excretion were measured. Seven days of GH treatment decreased urinary sodium excretion. Lithium clearance as a marker of proximal renal tubular sodium reabsorption was unaffected by GH treatment. ECW was increased after both short- and long-term treatment. This increase was inversely correlated to the decrease in diastolic blood pressure (r = -0.70, P = 0.02) between baseline and 12 months. Short-term treatment increased PRA and decreased BNP. The increase in PRA correlated with an increase in 24-h urinary norepinephrine excretion (r = 0.77, P < 0.01). Glomerular filtration rate and renal plasma flow did not change during treatment. The sodium- and water-retaining effect of GH takes place in the distal nephron. The sustained increase in ECW in response to GH is associated with an unchanged or decreased blood pressure. This together with unchanged or decreased atrial natriuretic peptides and BNP may prevent pressure-induced escape of sodium.

Background: Determination of urinary catecholamines (CATs) is considered important for clinical diagnosis of pheochromocytoma, paraganglioma, and neuroblastoma. The major disadvantages of existing tests include relatively long instrumental analysis time and potential interference from drugs and drug metabolites that are structurally similar to CATs., Methods: CATs were extracted from a 300-microL aliquot of urine by a two-step liquid-liquid extraction method specific for compounds containing a catechol group. Chromatographic separation did not require the use of ion-pairing reagents, which typically hinder MS detection but are frequently used in HPLC analysis of CATs. Instrumental analysis was performed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the multiple-reaction monitoring mode. Stable-isotope-labeled CATs were used as internal standards., Results: Epinephrine (E), norepinephrine (NE), and dopamine (D) were measured within 3.5 min instrumental run time. Quantification limits were 2.5 microg/L for E and D and 10 microg/L for NE. The total imprecision (CV) was < or =9.6%; extraction recoveries were 71% +/- 12%., Conclusions: HPLC with ESI-MS/MS in combination with sample preparation specific to catechol group-containing compounds allows rapid testing for disorders associated with increased CAT concentrations. The method is free of interferences from drugs and drug metabolites, which commonly interfere with HPLC methods.

Background: Earlier studies from this laboratory showed that central angiotensin II (AngII) receptors are upregulated by chronic cold exposure. The purpose of this study was to determine whether central AngII receptors may play a role in the development of cold-induced hypertension., Methods: Four groups of rats (six rats each) were used. Two groups were exposed to cold (5 degrees C) and the other two groups were kept at 25 degrees C. One cold-exposed and one warm-adapted group were treated chronically, via osmotic minipumps, with AngII type 1 (AT1) receptor blocker (losartan, 6.0 microg/2.5 microL/h, intracerebroventricularly) at the beginning of cold exposure., Results: Systolic blood pressure (BP) of the cold-exposed untreated group increased during week 1 of cold exposure and rose to 160+/-4 mm Hg by week 4, whereas BP of the losartan-treated group in cold did not increase and remained at 121+/-3 mm Hg. Cold-induced increases in drinking response to AngII, plasma renin activity, and urine norepinephrine output disappeared in the treated rats, indicating blockade of central AngII receptors. Withdrawal of losartan at 4 weeks resulted in an increase in BP of this group to the cold-exposed untreated level, which was accompanied by an increase in the above parameters. Significant increases in AngII-induced drinking response and hypothalamic AT1 receptor mRNA content of the cold-exposed rats indicate upregulation of AngII receptors during chronic cold exposure. Hypothalamic AngII level was not affected by cold exposure., Conclusion: Upregulation of brain AT1 receptors plays a role in the development of cold-induced hypertension.

Most, but not all, pheochromocytomas can be localized by computed tomography or magnetic resonance imaging. Here we introduce two novel approaches for localization of pheochromocytoma in a patient in whom conventional imaging modalities failed to show the tumor. First, we establish that measurements of plasma free metanephrines coupled with vena caval sampling are useful for localizing occult pheochromocytoma, particularly when elevations in plasma catecholamines are slight or intermittent. Second, we show that positron emission tomographic scanning using the imaging agent 6-[18F]fluorodopamine as a substrate for the norepinephrine transporter offers a highly effective method for tumor localization. These novel approaches may be of value in difficult cases, where biochemical and clinical evidence of pheochromocytoma is compelling, yet conventional imaging modalities fail to locate the tumor.

The mechanisms leading to alterations in plasma melatonin (MT) levels with testosterone replacement in Klinefelter's syndrome (KS) remain elusive. We investigated early morning plasma MT levels, urinary 6-sulfatoxymelatonin (6-SM) levels, and urinary catecholamine levels before and 6 months after testosterone treatment in 31 patients with KS and 20 healthy males to demonstrate whether alterations in plasma MT levels in such patients are due to subtle changes in sympathoadrenal activity and/or alterations in the hepatic indolamine metabolism influenced by testosterone replacement. The plasma MT level was measured by RIA. The sensitivity of the test was 10.7 pmol/L. The 6-SM level was measured by enzyme-linked immunosorbent assay. Urinary catecholamines were determined by high performance liquid chromatography. The pretreatment mean plasma MT level was insignificantly higher in the patient group than in the control group (72.57 +/- 74.82 vs. 42.37 +/- 29.02 pmol/L; z = -1.218; P = 0.223). The pretreatment urinary 6-SM and norepinephrine (NE) levels were significantly lower and, the epinephrine (E) and dopamine levels were insignificantly lower in the patient group than those in the control group [6-SM, 76.54 +/- 31.92 vs. 125.49 +/- 50.16 nmol/L (z = -3.727; P < 0.001); NE, 120.79 +/- 58.33 vs. 178.84 +/- 81.61 nmol/day (z = -2.585; P = 0.01); E, 31.27 +/- 27.42 vs. 34.65 +/- 28.33 nmol/day (z = -0.39; P: = 0.692); dopamine, 1577.02 +/- 863.02 vs. 1812.32 +/- 677.59 nmol/day (z = -1.03, P = 0.308)]. After testosterone replacement, plasma MT levels were significantly decreased (72.57 +/- 74.82 vs. 24.73 +/- 23.61 pmol/L; z = -4.29; P < 0.001), and urinary 6-SM, NE, E, and dopamine levels were significantly increased [6-SM, 25.04 +/- 10.44 vs. 40.05 +/- 17.65 ng/mL (z = -4.78; P < 0.001); NE, 120.78 +/- 58.33 vs. 154.08 +/- 61.35 nmol/day (z = -4.27; P < 0.001); E, 31.27 +/- 27.42 vs. 40.74 +/- 30.04 nmol/day (z = -4.22; P < 0.001); dopamine, 1577.02 +/- 863.02 vs. 2162.67 +/- 823.15 (z = -6.127; P < 0.001)]. There was no relation between plasma MT levels, urinary 6-SM, and catecholamine levels and levels of gonadotropins or gonadal steroids either before or after treatment. We demonstrate that in untreated KS, plasma MT levels tend to be higher than those in normal controls, whereas those of the melatonin metabolite 6-SM and those of NE in urine tend to be lower. After testosterone treatment, however, plasma MT levels fall significantly, whereas urinary levels of 6-SM and NE rise. Our data show that the effect of testosterone is mediated by enhanced metabolism of melatonin, not by any effect on net sympathetic outflow, and that the increase in plasma melatonin in untreated KS patients also results from an alteration in the rate of melatonin metabolism and not from increased net sympathetic activity.

Mitochondrial uncoupling protein-2 and -3 (UCP2 and UCP3) may be involved in the modulation of resting metabolic rate and energy balance. To investigate their variability, the influence of this on the variability of energy expenditure, and potential regulatory factors of the expression of the corresponding genes, we measured their messenger ribonucleic acids (mRNAs) in muscle and white adipose tissue of lean, healthy men and correlated the abundance of these mRNAs (attomoles per microg total RNA) with measures of resting metabolic rate, hormone levels (thyroid hormones, insulin, glucagon, leptin, and catecholamines), and fuels potentially involved in energy balance regulation. We also investigated whether the thiazolidinedione, troglitazone, stimulates UCP2 and UCP3 mRNA levels to follow up on the observation that this antidiabetic drug increases the levels of expression in cultured cells. We found UCP2 and UCP3 mRNA levels to be highly variable and poorly correlated with measures of energy expenditure and with most factors affecting energy balance. Only nocturnal urinary norepinephrine excretion could explain a significant fraction of the variability in both UCP2 and UCP3 expression in muscle, but not adipose tissue. Thyroid hormone and norepinephrine excretion were found to contribute to the variability of resting metabolic rate, but this could not be explained by an effect on UCP mRNAs. Troglitazone affected neither the expression of UCPs nor the hormones or the measures of metabolic rate investigated. In conclusion, our results show that the expression of UCP2 and UCP3 genes is quite variable in healthy males and that this variability does not explain that in resting energy expenditure, and suggest that sympathetic activity is an important potential regulator of the expression of these proteins in skeletal muscle. However, the data do not support the concept that regulation of the expression of these genes is the most important level of control of UCP3 and UCP2 functions, and other levels of control have to be invoked.

Objective: To conduct an epidemiological study on pheochromocytoma in Italy., Methods: Data on 284 patients with pheochromocytoma observed between 1978 and 1997 were collected from 18 Italian centers through a questionnaire reporting epidemiological, clinical, laboratory, radiological and surgical data., Results: 53.6% of the patients were females and 46.4% were males. Thirty-two tumors were discovered as incidental adrenal masses. The most frequent referred symptoms were palpitations (58.1%), headache (51.9%), sweating (48. 8%) and anxiety (35.3%). Their association was present only in 15.5% of patients. Paroxysmal symptoms were reported in 67.1% and hypertensive crises in 59.7% of patients. Normal blood pressure (systolic and diastolic) was present both in the supine and upright positions in 21.1% of patients. Among laboratory assays, urinary vanylmandelic acid (VMA) was the most widely used (58.1%) and was the least sensitive (25% of false negative results). Basal plasma catecholamines were found to be normal in 11.3% of patients but were always elevated when sampled during a hypertensive paroxysm. A clonidine suppression test was performed in 38 patients with no adverse side effects. It gave a false negative response in 2 patients. A glucagon test was performed in 21 patients. It was interrupted for acute hypertension in 52.4% of patients. Only 5/21 patients were normotensive and had normal basal plasma catecholamines. In these patients the test gave a positive response in four (80%). CT (79.6%) and I-MIBG scintigraphy (68.5%) were the most widely used methods for tumor localization. CT sensitivity was 98.9% for intra-adrenal and 90.9% for extra-adrenal tumors. MIBG sensitivity was 88.5%. In the 263 patients who underwent surgery, the tumor was intra-adrenal in 89.4%, extra-adrenal in 8.5%, intra- and extra-adrenal in 2.1%, and bilateral in 11.0% of patients. Malignancy was reported in 9.9% of cases. Surgery caused remission of hypertension in 59.3%, improvement in 26.8%, and no changes in 13. 9% of patients. In the last group the interval between initial symptoms and diagnosis was significantly longer., Conclusions: The present study confirms that the clinical presentation of pheochromocytoma is variable and aspecific. Normotension is often present and often the tumor is discovered incidentally. An indication for the routine use of screening methods more sensitive than urinary VMA is strongly suggested. The clonidine test was found to be safe and should be preferred to the glucagon test which has to be restricted to very selected patients. CT and MIBG scintigraphy are almost always successful in localizing the tumor. Reversal of hypertension by surgery seems to depend on an early diagnosis.

Background: In the present study, the impact of gender, oral contraceptives, and ambulation on serum growth hormone (GH) and urinary catecholamines was examined in healthy young adults., Methods: Twenty-one medical student volunteers--7 men, 7 women, and 7 women taking oral contraceptives--were investigated. Serum samples were drawn every second hour during a 24-h period. At 0800 the first morning, serum samples were drawn while subjects were in the ambulatory state; the next morning, serum samples were drawn at 0800 while the subjects were still resting in bed., Results: During the daytime, GH concentrations were sevenfold higher in the women than in the men, a difference larger than described previously. During the night, there was no gender difference. In the morning, ambulatory GH concentrations were 28-fold higher in the women than in the men, whereas supine GH concentrations were only 4.6-fold higher in the women than in the men. Daytime urinary output of epinephrine was lower in the women than in the men, whereas there was no difference at night. Women using estrogen-containing oral contraceptives had lower epinephrine and higher GH values than women not taking oral contraceptives. In women, morning GH concentrations were higher in the ambulatory than in the resting state, whereas they were lower in the ambulatory state than in the resting state in men., Conclusions: The secretion of GH and epinephrine is gender-dependent and differs during the daytime in a reciprocal manner, with higher GH and lower epinephrine in women than in men. Oral contraceptives appear to further increase such differences. It seems likely that the data reflect a gender difference in the utilization of substrates for energy production.

The influence of acute sleep deprivation during the first part of the night on 24-h blood pressure monitoring (ABPM) was studied in 36 never-treated mild to moderate hypertensive patients. According to a crossover design, they were randomized to have either sleep deprivation or a full night's sleep 1 week apart, during which they were monitored with ABPM. Urine samples for analysis of nocturnal urinary excretion of norepinephrine were collected. During the sleep-deprivation day, both mean 24-h blood pressure and mean 24-h heart rate were higher in comparison with those recorded during the routine workday, the difference being more pronounced during the nighttime (P < .01). Urinary excretion of norepinephrine showed a significant increase at night during sleep deprivation (P < .05). Blood pressure and heart rate significantly increased in the morning after a sleep-insufficient night (P < .05). These data suggest that lack of sleep in hypertensive patients may increase sympathetic nervous activity during the night and the following morning, leading to increased blood pressure and heart rate. This situation might represent an increased risk for both target organ damage and acute cardiovascular diseases.

Background: It is uncertain whether biochemical markers of catecholamine secretion in patients with phaeochromocytoma correlate with tumour ultrastructure granule morphology., Methods: Fifteen patients with an adrenal phaeochromocytoma (n=13) or paraganglioma (n=2) (three men, 12 women; age 17-79 years) were studied. Catecholamine secretion was estimated by measuring urinary levels of free noradrenaline, adrenaline and dopamine. The number and type of secretory granules were evaluated by two independent observers on electron micrographs (area analysed approximately 70 microm2). Large round or elongated medium-density granules were adrenaline-type granules, whereas electron-dense granules lying in a vacuole were of noradrenaline type., Results: No correlation was found between noradrenaline output and the number or percentage of noradrenaline-type granules, although tumours with normal noradrenaline output had only a minority of this type of granule (less than 25 per cent). Adrenaline-type granules were predominant (77 per cent of 163 granules) in a tumour secreting only adrenaline, but the proportion of adrenaline-type granules in six tumours with normal adrenaline output varied significantly (range 7-89 per cent). It was not possible to evaluate the granule type associated with dopamine secretion because one tumour secreting 14900 nmol dopamine and 1570 nmol adrenaline daily had a predominance of noradrenaline-type granules (63 per cent of 132 granules) and two dopamine-secreting tumours (5500 and 4250 nmol per day respectively) had 93 and 13 per cent noradrenaline-type granules., Conclusion: The lack of correlation between hormone output and granularity suggests that other factors determine secretory patterns in these tumours.

Background: Although intrarenal dopamine is known to behave as an endogenous natriuretic hormone the role of the renal dopaminergic system in the sodium handling of nephrotic oedema remains unknown., Study Design: We monitored the daily urinary excretion of free dopamine, L-DOPA-its precursor, and its metabolites, DOPAC and HVA, during sodium retention accompanying the nephrotic state and natriuresis leading to oedema mobilization in eight patients (mean age 8.0+/-2.4 years) with drug-induced remission of minimal-change nephrotic syndrome (MCNS)., Results: During natriuresis the urinary levels of dopamine did not increase in parallel with sodium excretion in any of the eight patients studied. Moreover, after remission of the nephrotic syndrome the urinary levels of dopamine were significantly lower than during the nephrotic state (1565.3+/-361.7 vs 2416.1+/-558.4, P= 0.02). In contrast, the urinary excretion of L-DOPA increased markedly during natriuresis resulting from remission of proteinuria (from 87.0+/-40.5 up to 296.9+/-86.3 nmol/24 h; P< 0.01)., Conclusion: We conclude that the natriuretic response resulting from drug-induced remission of proteinuria in MCNS is accompanied by a decrease in the renal uptake/decarboxylation of L-DOPA to dopamine.

Background: Cheyne-Stokes respiration disrupts sleep, leading to daytime somnolence and cognitive impairment. It is also an independent marker of increased mortality in heart failure. This study evaluated the effectiveness of oxygen therapy for Cheyne-Stokes respiration in heart failure., Methods: Eleven patients with stable heart failure and Cheyne-Stokes breathing were studies. Oxygen and air were administered for 4 weeks in a double-blind, cross-over study. Sleep and disordered breathing was assessed by polysomnography. Symptoms were assessed using the Epworth Sleepiness Scale, visual analogue and quality of lift scores. Cognitive function was assessed by neuropsychometric testing. Overnight urinary catecholamine excretion was used as a measure of sympathetic nerve activity., Results: Ninety-seven percent of apnoeas were central in origin. Oxygen therapy reduced the central apnoea rate (18.4 +/- 4.1 vs 3.8 +/- 2.1 per hour; p = 0.05) and periodic breathing time (33.6 +/- 7.4 vs 10.7 +/- 3.9% of actual sleep time; p = 0.003). Oxygen did not improve sleep quality, patient symptoms or cognitive failure. Oxygen reduced urinary noradrenaline excretion (8.3 +/- 1.5 vs 4.1 +/- 0.6 nmol.mmol-1 urinary creatinine; p = 0.03)., Conclusion: Oxygen stabilized sleep disordered breathing and reduced sympathetic activity in patients with heart failure and Cheyne-Stokes respiration. We were unable to demonstrate an effect on either patient symptoms or cognitive function.

The objective of this study was to compare average stress levels during the month of conception to those of previous infertile months. We postulated that stress level during the actual month of conception would be lower than that during previous non-conception cycles. Thirteen normal women from the general community, who were attempting pregnancy, kept daily records of coital activity and basal body temperature, and twice a month completed self-administered questionnaires and provided a 12 h overnight urine sample. On average, women reported significantly more favourable mood states on standard psychometric tests, during the month of conception than during the previous non-conception cycles. In addition, they felt significantly less 'hassled' during the month of conception. However, mean urinary hormone excretion of adrenaline, noradrenaline and cortisol did not significantly differ between conception and non-conception cycles and there was little relationship between the psychological measures of mood state and excretion of adrenaline and cortisol. There was no evidence of increased coital frequency during the month of conception when mood states were improved, suggesting that stress effects on libido were unlikely to account for the findings. The results support the conclusion that psychosocial stress influences fertility in females but as yet mechanisms remain unclear.

The aim of the study was to assess the clinical significance of the blood pressure (BP) reaction to standing in 1029 stage I hypertensives. Office BP was measured six times in the supine position and six times after 2 min of standing. All subjects underwent 24-h ambulatory BP monitoring, and measurements of 24-h urinary epinephrine and norepinephrine excretion. Echocardiography was performed in 636 patients. With use of mixture analysis we could single out a population with abnormal diastolic BP response to standing (hyperreactors, n = 95). These subjects had a diastolic BP increase from lying to standing of >11 mm Hg. The other subjects were defined as normoreactors (n = 934). Office systolic BP was similar in the two groups. Diastolic BP was lower (91 +/- 6 mm Hg v 95 +/- 5 mm Hg, P < .0001) and heart rate was higher in the hyperreactors (77 +/- 10 beats/min v 75 +/- 9 beats/min, P = .004). After adjusting for age, gender, and smoking habits the statistical significance did not change. Adjusted 24-h systolic BP (P = .02) and diastolic BP (P = .02) were higher in the hyperreactors than in the normoreactors. Hyperreactors were characterized by higher cardiac index (3.2 +/- 0.8 L/min/m2 v 3.0 +/- 0.7 L/min/m2, P = .008 for adjusted values), lower total peripheral resistance (1420 +/- 330 dyne/sec/cm(-5) v 1600 +/- 380 dyne/sec/cm(-5), P = .003), and higher urinary norepinephrine output (114.9 +/- 80.3 microg/24 h v 90.6 +/- 78.5 microg/24 h, P = .03). Dimensional echocardiographic data and albumin excretion rate did not differ between the two groups. In conclusion, mixture analysis allowed us to identify a population of young mild hypertensives with exaggerated BP response to standing. Hyperreactors were characterized by higher whole-day BP and by a hyperkinetic hemodynamic pattern as a result of increased sympathetic tone.

The functional strength, flexibility, and ranges of motion of the lower extremities, as well as hormonal balance, estimated by urinary excretion of adrenaline and noradrenaline and serum determinations of testosterone and cortisol, were studied with six physically active army officers participating in a 4-day march totaling 185 km. Catecholamine excretion rates showed cumulatively increased sympathoadrenal stress, and the effects on serum testosterone and cortisol concentrations were minor. Also, leg measurements showed no signs of edema, decreases in flexibility, or decreases in functional strength. Most pain (75%) experienced by the subjects was located in the feet and caused by abrasions and blisters. Only a small portion of perceived pains (25%) was associated with muscle soreness. Serum creatine kinase activity was slightly (ca. 400-650%) increased during the marching days. Thus, soldiers who are in good physical condition and are accustomed to marching are able to walk four marathons on successive days, while carrying 10-kg backpacks, without any major adverse effects on the musculature of their lower extremities.

Despite advances in medical therapy of congestive heart failure (CHF), morbidity and mortality for this disorder remain high. One factor that could contribute to the poor prognosis of CHF is Cheyne-Stokes respiration with central sleep apnea (CSR-CSA). This breathing disorder is a frequent complication of CHF, where it is associated with increased mortality. One reason for this higher mortality may be that apnea-related hypoxia and arousals from sleep can increase sympathetic nervous system activity (SNA), as manifested by increases in overnight urinary and daytime plasma norepinephrine concentrations ([UNE] and [PNE], respectively). Recently published randomized trials have demonstrated that nasal continuous positive airway pressure (CPAP), if applied nightly at high enough levels over periods of at least 1-3 months, can alleviate CSR-CSA in patients with CHF in association with hemodynamic improvement, as evidenced by increased left ventricular ejection fraction (LVEF) and inhibition of SNA, as manifest by reductions in [UNE] and [PNE]. These findings indicate a role for CPAP as a non-pharmacologic adjunctive therapy for CHF complicated by CSR-CSA. Longer-term trials of CPAP are needed to determine whether this intervention can provide long-lasting clinical benefit to patients with CHF and CSR-CSA.

We hypothesized that withdrawal of nasal continuous positive airway pressure (CPAP) in patients with sleep apnea would produce a measurable stress response. To test this hypothesis, we ceased CPAP in eight patients regularly using nasal CPAP long term and measured the effect on sleep apnea as well as plasma and urinary levels of the stress hormones, noradrenaline, cortisol and adrenocorticotropic hormone (ACTH). CPAP withdrawal led to an immediate recurrence of sleep apnea with increases in apnea index, arousal index and oxygen desaturation (all p < .0001) but no change in levels of noradrenaline, cortisol or ACTH. We conclude that acute withdrawal of CPAP in patients with sleep apnea does not lead to a classic stress response.

The detection and diagnosis of pheochromocytoma are highly dependent on the biochemical confirmation of excessive catecholamine release by the tumor. As the reliability of baseline plasma catecholamines in the detection of pheochromocytoma is questionable, assessment of the excretion rates of catecholamines or metabolites in 24-h urine collections remains the mainstay of initial biochemical investigation. However, diagnostic difficulties can arise from incomplete collection of 24-h specimens or equivocal increases in catecholamines due to stress. To investigate the diagnostic validity of shorter collection times for the biochemical detection of this tumor, we measured the excretion of catecholamines and metabolites after sleep, a period associated with decreased sympathetic activity. Overnight catecholamines, metanephrines, and 4-hydroxy-3-methoxymandelic acid (HMMA) levels were measured in 16 patients with histologically confirmed pheochromocytomas, 166 patients with hypertension, and 24 normotensive subjects. All measurements were performed by high performance liquid chromatography with electrochemical detection. Overnight excretion of norepinephrine in the tumor group (range, 86-1552 nmol/mmol creatinine) was significantly different (P <0.001) from that in the nontumor group (14-63 nmol/mmol creatinine). Autonomous secretion of norepinephrine was evident in all urine collections, including a patient with a predominantly epinephrine-secreting tumor. Overnight normetanephrine levels displayed a similar excretion pattern (P < 0.001), whereas overnight epinephrine and metanephrine levels were normal in 10 of the 16 patients with pheochromocytoma. In contrast, HMMA excretion in overnight urine collections was highly variable, with only 6 of the 16 patients in the tumor group having consistently elevated excretion. In the other 10 patients, overnight HMMA excretion showed a high intravariability. The measurement of catecholamines and total metanephrines after sleep is a viable approach for the exclusion of pheochromocytoma, as overnight urine collections completely differentiated patients with pheochromocytoma from hypertensive patients. Compared to 24-h results, overnight urinary norepinephrine levels provided a better diagnostic sensitivity and specificity (100% sensitivity and 98% specificity compared with 88% and 82%). Sleep urine samples simplify the collection protocol while avoiding the effects of stress and exercise.