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Background/aims Trace amines (TA) are small organic compounds that have neuromodulator activity due to their interaction with some neuron-related receptors, such as trace amine associated receptors (TAARs), α2-adrenergic receptor (α2-AR) and s-adrenergic receptor (s-AR). However, there is little information on whether TA and dopamine (DOP) can interact with other adrenergic receptors (ARs) such as the mammalian α1-AR and the bacterial counterpart QseC, which is involved in quorum sensing of some Gram-negative pathogens. The aim of this study was to investigate the interaction of TA and DOP with α1-AR and QseC. Methods We performed an in silico study using 3D structure from SWISS MODEL and analyzed the protein interaction via molecular docking using PyMol, PoseView and PyRX 8.0. For the in vitro study, we investigated the QseC kinase activity by measuring the remaining ATP in a reaction containing QseC-enriched membrane incubated together with purified QseB and EPI, TA, DOP, or PTL respectively. We also measured the intracellular Ca++ levels, which represents the α1-AR activation, in LNCAP (pancreatic cell line) cells treated with EPI, TA, DOP and PTL respectively using a fluorescence-based assay. The LNCAP cell proliferation was measured using an MTT-based assay. Results Our in silico analysis revealed that TAs and DOP have high binding affinity to the human α1-AR and the bacterial adrenergic receptor (QseC), comparable to epinephrine (EPI). Both are membrane-bound kinases. Experimental studies with pancreatic cell line (LNCAP) showed that the TAs and DOP act as α1-AR antagonist by counteracting the effect of EPI. In the presence of EPI, TA and DOP trigger an increase of the intracellular Ca++ levels in the LNCAP cells leading to an inhibition of cell proliferation. Although in silico data suggest an interaction of TA and DOP with QseC, they do not inhibit the kinase activity of QseC, a histidine kinase receptor involved in quorum sensing which is also sensitive to EPI. Conclusion Our study showed that the TAs and DOP act as α1-AR antagonist but no effect was observed for QseC.

Post-inflammatory erythema (PIE) is a common sequalae of acne inflammation, persistent post acne erythema (PAE) is cosmetically unacceptable and sometimes its complete clearance could not be achieved. Oxymetazoline (OXZ) is a synthetic, direct-acting, sympathomimetic agonist that is highly selective for the 1α-adrenoceptor. It is a potent vasoconstrictor and well known for its ability to clinically 'get the red out'.The aim of this study was to evaluate the efficacy and safety of topical oxymetazoline (OXZ) 1.5% in treatment of post acne erythema (PAE) in a left to right face comparative study.This study was conducted on 40 patients diagnosed with post acne erythema for at least 3 months, the left side of the face was treated with topical OXZ 1.5% in liposomal base and was compared to the right side to which topical lipogel was applied as a control.According to the investigator's global assessment of photographs and the analysis of erythema with image analysis software, topical OXZ was significantly effective in diminishing PAE when compared to topical placebo lipogel.Topical OXZ is a safe and effective treatment for post-acne erythema.

Background: The impact of nipple sensation and its relationship to sexual function have often been neglected in medical literature. However, several recent studies report the importance of the nipp...

It was demonstrated that α1 adrenergic receptor (α1-AR) activation by phenylephrine (PE) attenuated cardiac dysfunction in lipopolysaccharide (LPS)-challenged mice. However, it is unclear whether PE suppresses sepsis-induced cardiomyocyte apoptosis. Here, we investigated the effects of PE on cardiomyocyte apoptosis in LPS-treated adult rat ventricular myocytes (ARVMs) and septic rats induced by cecal ligation and puncture. Cardiomyocyte apoptosis and caspase activity were detected by TUNEL and spectrophotometrical assay, respectively. Bax, Bcl-2 and cytochrome c (Cyt c) levels as well as IκBα, ERK1/2, p38 MAPK, JNK and cardiac troponin I (cTnI) phosphorylation were analyzed by Western blotting, and TNF-α concentration was analyzed by ELISA. PE inhibited LPS-induced caspase-3 activation in ARVMs, which was reversed by prazosin (a membrane permeable α1-AR antagonist), but not by CGP12177A (a membrane impermeable α1-AR antagonist). PE upregulated phosphorylated ERK1/2 and Bcl-2 contents, decreased TNF-α and Bax levels, Cyt c release, caspase-8/-9 activities as well as IκBα, p38MAPK and JNK phosphorylation in LPS-treated ARVMs, all of which were abolished by prazosin. Treatment with U0126 (a specific ERK1/2 inhibitor) reversed the effects of PE on IκBα, p38MAPK and JNK phosphorylation as well as caspase-3/-8/-9 activation in LPS-treated ARVMs. In septic rats, PE not only inhibited myocardial apoptosis as well as IκBα, p38MAPK, and JNK phosphorylation, but also upregulated myocardial phosphorylated ERK1/2. Furthermore, PE inhibited myocardial cTnI phosphorylation and improved cardiac function in septic rats. Taken together, our data suggest that α1-AR activation by PE inhibits sepsis-induced cardiomyocyte apoptosis and cardiac dysfunction via activating ERK1/2 signal pathway.

ImportanceAlpha-1-adrenergic receptor antagonists (α1-blockers) can abrogate pro-inflammatory cytokines and may improve outcomes among patients with respiratory infections. Repurposing readily available drugs such as α1-blockers could augment the medical response to the COVID-19 pandemic.ObjectiveTo evaluate the association between α1-blocker exposure and COVID-19 mortalityDesignReal-world evidence studySettingPatient level data with 32,355 records tested for SARS-CoV-2 at the Mount Sinai Health System including 8,442 laboratory-confirmed cases extracted from five member hospitals in the New York City metropolitan area.Participants2,627 men aged 45 or older admitted with COVID-19 between February 24 and May 31, 2020Exposuresα1-blocker use as an outpatient or while admitted for COVID-19Main Outcomes and MeasuresIn-hospital mortalityResultsMen exposed to α1-blockers (N=436) were older (median age 73 vs. 64 years, P1-blockers was not associated with COVID-19 hospital outcomes, though there was a trend towards significance (OR 0.749, 95% CI 0.527-1.064; P=0.106). Conversely, inpatient use of α1-blockers was independently associated with improved in-hospital mortality in both multivariable logistic (OR 0.633, 95% CI 0.434-0.921; P=0.017) and Cox regression analyses (HR 0.721, 95% CI 0.572-0.908; P=0.006) adjusting for patient demographics, comorbidities, and baseline vitals and labs. Age-stratified analyses suggested greater benefit from inpatient α1-blocker use among younger age groups: Age 45-65 OR 0.384, 95% CI 0.164-0.896 (P=0.027); Age 55-75 OR 0.511, 95% CI 0.297-0.880 (P=0.015); Age 65-89 OR 0.810, 95% CI 0.509-1.289 (P=0.374).Conclusions and RelevanceInpatient α1-blocker use was independently associated with improved COVID-19 mortality among hospitalized men. Clinical trials to assess the therapeutic value of α1-blockers in COVID-19 are warranted.

Stress activates the sympathetic nervous system and is linked to impaired fertility in man. We hypothesized that catecholamines by acting on testicular cells have a role in these events, possibly by fostering an inflammatory environment. The cells of the wall of seminiferous tubules, human testicular peritubular cells (HTPCs), express adrenergic receptors (ADRs) α1B, α1D, β1 and β2. A selective α1-ADR agonist, phenylephrine, increased intracellular Ca 2+ -levels in cultured HTPCs and induced COX-2, IL-6 and MCP-1 mRNA expression without affecting IL-1β mRNA. These changes were paralleled by a significant increase in the secretion of IL-6 and MCP-1. Epinephrine was also effective, but salbutamol, a selective β2-ADR agonist was not. Our results suggest that stress-associated elevation of catecholamines may be able to promote inflammatory events by targeting peritubular cells in the human testis. Blockage of α1-ADRs may therefore be a novel way to interfere with stress-related impairment of male reproductive functions. Fil: Rossi, Soledad Paola. Ludwig Maximilians Universitat; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Walenta, Lena. Ludwig Maximilians Universitat; Alemania Fil: Rey Ares, Veronica. Ludwig Maximilians Universitat; Alemania Fil: Köhn, Frank-Michael. Andrologicum; Alemania Fil: Ulrich Schwarzer, J.. Andrology Center Munich; Alemania Fil: Welter, Harald. Ludwig Maximilians Universitat; Alemania Fil: Calandra, Ricardo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Frungieri, Monica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Mayerhofer, Artur. Ludwig Maximilians Universitat; Alemania

Background: Binge-eating disorder is a pervasive addiction-like disorder that is defined by excessive and uncontrollable consumption of food within brief periods of time. The aim of the current study was to examine the role of the brain noradrenergic system in binge-like eating through the use of the alpha-1 adrenergic receptor antagonist prazosin. Methods: For this purpose, we employed a limited access model whereby male Wistar rats were allowed to nosepoke for either chow (Chow rats) or a sugary, highly palatable food (Palatable rats) for 1 h/day. The effects of prazosin (0, 0.5, 1 and 2 mg/kg, i.p.) were tested in a fixed ratio 1 (FR1) and progressive ratio (PR) schedule of reinforcement. Results: The results show that prazosin preferentially reduced the responses for palatable food in a FR1 reinforcement schedule; when tested in a PR schedule of reinforcement, prazosin increased breakpoint in both Chow and Palatable rats, but more potently and more efficaciously in the latter. Our results suggest that prazosin treatment preferentially increased the motivational properties of the palatable diet. Conclusions: The current findings provide the characterization of the effects of prazosin on binge-like eating and offer support to the existing literature showing the important role of the noradrenergic system in addiction-like behavior.

Exposure to drug-associated cues evokes drug-craving and upregulates noradrenaline (NA) and dopamine (DA) system activity. Importantly, conditional stimulus-induced drug-seeking behavior depends particularly on phasic DA signaling downstream from the ventral tegmental area (VTA), a midbrain structure key for the regulation of cocaine seeking. In particular, the activity of the alpha1-adrenergic receptor (α1-AR), which has recently been hypothesized to modulate salience encoding, is capable of bidirectional regulation of VTA dopaminergic activity. Thus, the impact of the conditional stimuli (CSs) on drug-seeking behavior might involve α1-AR signaling in the VTA. To date, the role of VTA α1-ARs in regulating CS-induced cocaine seeking has not been studied. In male Sprague–Dawley rats, we found that intra-VTA terazosin, a selective α1-AR antagonist, attenuated CS-induced cocaine seeking in a novel context and under extinction conditions, as well as CS-induced reinstatement of cocaine seeking. In contrast, terazosin microinfusion in a dose that attenuated CS-induced cocaine seeking had no effects on CS-induced food seeking or stress (2 mg/kg yohimbine)-evoked reinstatement of cocaine seeking. The potential nonspecific effects (sedative, anxiogenic) of α1-AR blockade of the VTA were also measured in the open-field test. Finally, using immunostaining, we demonstrated dopamine β-hydroxylase (DBH)-positive afferents in the VTA of cocaine-abstinent rats, providing a neuroanatomical substrate for the α1-AR mechanism. These results demonstrated for the first time that NAergic signaling via VTA α1-ARs potently and selectively regulates CS-induced cocaine seeking. Our findings provide new neuronal mechanisms that regulate cocaine craving.

Although convention dictates that G protein-coupled receptors localize to and signal at the plasma membrane, accumulating evidence suggests that G protein-coupled receptors localize to and signal at intracellular membranes, most notably the nucleus. In fact, there is now significant evidence indicating that endogenous alpha-1 adrenergic receptors (α1-ARs) localize to and signal at the nuclei in adult cardiac myocytes. Cumulatively, the data suggest that α1-ARs localize to the inner nuclear membrane, activate intranuclear signaling, and regulate physiologic function in adult cardiac myocytes. Although α1-ARs signal through Gαq, unlike other Gq-coupled receptors, α1-ARs mediate important cardioprotective functions including adaptive/physiologic hypertrophy, protection from cell death (survival signaling), positive inotropy, and preconditioning. Also unlike other Gq-coupled receptors, most, if not all, functional α1-ARs localize to the nuclei in adult cardiac myocytes, as opposed to the sarcolemma. Together, α1-AR nuclear localization and cardioprotection might suggest a novel model for compartmentalization of Gq-coupled receptor signaling in which nuclear Gq-coupled receptor signaling is cardioprotective.

BackgroundIrreversible hemorrhagic shock is characterized by hyporesponsiveness to vasopressor and fluid therapy. Little is known, however, about the mechanisms that contribute to this phenomenon. Previous studies have shown that decreased intestinal perfusion in hemorrhagic shock leads to proteolytically mediated increases in gut permeability, with subsequent egress of vasoactive substances systemically. Maintenance of blood pressure is achieved in part by α1 receptor modulation, which may be affected by vasoactive factors; we thus hypothesized that decreases in hemodynamic stability and vasopressor response in shock can be prevented by enteral protease inhibition.MethodsRats were exposed to experimental hemorrhagic shock (35 mm Hg mean arterial blood pressure for 2 hours, followed by reperfusion for 2 hours) and challenged with phenylephrine (2 μg/kg) at discrete intervals to measure vasopressor responsiveness. A second group of animals received enteral injections with the protease inhibitor tranexamic acid (TXA) (127 mM) along the small intestine and cecum 1 hour after induction of hemorrhagic shock.ResultsBlood pressure response (duration and amplitude) to phenylephrine after reperfusion was significantly attenuated in animals subjected to hemorrhagic shock compared with baseline and control nonshocked animals and was restored to near baseline by enteral TXA. Arteries from shocked animals also displayed decreased α1 receptor density with restoration to baseline after enteral TXA treatment. In vitro, rat shock plasma decreased α1 receptor density in smooth muscle cells, which was also abrogated by enteral TXA treatment.ConclusionResults from this study demonstrate that experimental hemorrhagic shock leads to decreased response to the α1-selective agonist phenylephrine and decreased α1 receptor density via circulating shock factors. These changes are mitigated by enteral TXA with correspondingly improved hemodynamics. Proteolytic inhibition in the lumen of the small intestine improves hemodynamics in hemorrhagic shock, possibly by restoring α1 adrenergic functionality necessary to maintain systemic blood pressure and perfusion.

Keratinocytes produce cytokines and nerve growth factor (NGF) as part of a repair response to injury, disease or stress, and express alpha1-adrenoceptors (α1-AR). The expression of these receptors is elevated in some inflammatory diseases and chronic pain conditions. In this study, we investigated whether inflammatory signalling affects α1-AR expression in keratinocytes in vitro. Tumor necrosis factor α (TNFα) was administered to human keratinocytes, after which the levels of other key pro-inflammatory cytokines and NGF were measured. The production of these cytokines and NGF increased in cells treated with TNFα compared to untreated cells. Furthermore, exposure to TNFα increased gene expression of the α1-AR subtype B in keratinocytes. Our results suggest that inflammatory cytokines released during injury stimulate α1-AR expression in keratinocytes. The up-regulation of α1-AR may amplify the adrenergic sensitivity of these cells to catecholamines released during sympathetic nervous system activation after injury which, in turn, could heighten the inflammatory response.

Background In recent years, the role of the sympathetic nervous system in bone metabolism has been revealed. Many studies have suggested that bone loss can be induced by continuously high sympathetic tone resulting from up-regulation of osteoclastogenesis and osteoclastic activity via β 2 -adrenergic receptors. Although the expression of α-adrenergic receptors in osteoblasts and osteoclasts has been demonstrated, the physiological roles of these receptors in bone metabolism remain unclear. In the present review, we provide an account of the role of α 1 -adrenergic receptors in bone metabolism. Conclusion Experimental studies in osteoblasts suggest that not only the suppression of β 2 -adrenergic receptors but also the activation of α 1 -adrenergic receptors could lead to a treatment for osteoporosis. Studying the signaling pathway will help elucidate the mechanism underlying the regulation of bone metabolism via the α 1 -adrenergic receptor and also facilitate the development of a novel therapeutic strategy for osteoporosis.

Disorders of ejaculation are the consequences of surgical procedures and with the use of various drugs. Until date, most drugs reported to induce ejaculatory dysfunctions such as retrograde ejaculation or dry orgasms share the capacity to significantly antagonize alpha 1-adrenergic receptor. Iloperidone, a new dopamine Type 2 and serotonin Type 2A antagonist similar to risperidone, provides better efficacy with lesser extra-pyramidal side effects. In addition, it also antagonize alpha 1-adrenergic receptor and alpha-2C receptors. Limited data is available for iloperidone-induced ejaculation dysfunction. This article features five schizophrenic patients which developed retrograde ejaculation during treatment with iloperidone. The ejaculatory dysfunction following treatment with iloperidone could be postulated due to blocking of alpha 1-adrenergic receptor.

Activity of the ventral tegmental area (VTA) and its terminals has been implicated in the Pavlovian associative learning of both stressful and rewarding stimuli. However, the role of the VTA noradrenergic signaling in fear responses remains unclear. We aimed to examine how alpha1-adrenergic receptor (α1-AR) signaling in the VTA affects conditioned fear. The role of α1-AR was assessed using the micro-infusions into the VTA of the selective antagonists (0.1-1 µg/0.5 µl prazosin and 1 µg/0.5 µl terazosin) in acquisition and expression of fear memory. In addition, we performed control experiments with α1-AR blockade in the mammillary bodies (MB) - a brain region with α1-AR expression adjacent to the VTA. Intra-VTA but not intra-MB α1-AR blockade prevented formation and retrieval of fear memories. Importantly, local administration of α1-AR antagonists did not influence footshock sensitivity, locomotion or anxiety-like behaviors. Similarly, α1-AR blockade in the VTA had no effects on negative affect measured as number of 22 kHz ultrasonic vocalizations during fear conditioning training. We propose that noradrenergic signaling in the VTA via α1-AR regulates formation and retrieval of fear memories but not other behavioral responses to stressful environmental stimuli. It enhances the encoding of environmental stimuli by the VTA to form and retrieve conditioned fear memories and to predict future behavioral outcomes. Our results provide novel insight into the role of the VTA α1-AR signaling in the regulation of stress responsiveness and fear memory.

Drug-primed reinstatement of cocaine seeking in rats is thought to reflect relapse-like behavior and is mediated by the integration of signals from mesocorticolimbic dopaminergic projections and corticostriatal glutamatergic innervation. Cocaine-primed reinstatement can also be attenuated by systemic administration of dopamine β-hydroxylase (DBH) inhibitors, which prevent norepinephrine (NE) synthesis, or by α1-adrenergic receptor (α1AR) antagonists, indicating functional modulation by the noradrenergic system. In the present study, we sought to further discern the role of NE in cocaine-seeking behavior by determining whether α1AR activation can induce reinstatement on its own or is sufficient to permit cocaine-primed reinstatement in the absence of all other AR signaling, and identifying the neuroanatomical substrate within the mesocorticolimbic reward system harboring the critical α1ARs. We found that while intracerebroventricular infusion of the α1AR agonist phenylephrine did not induce reinstatement on its own, it did overcome the blockade of cocaine-primed reinstatement by the DBH inhibitor nepicastat. Furthermore, administration of the α1AR antagonist terazosin in the medial prefrontal cortex (mPFC), but not the ventral tegmental area (VTA) or nucleus accumbens (NAc) shell, attenuated cocaine-primed reinstatement. Combined, these data indicate that α1AR activation in the mPFC is required for cocaine-primed reinstatement, and suggest that α1AR antagonists merit further investigation as pharmacotherapies for cocaine dependence.

The role played by spinal adrenergic and cholinergic receptors in the antinociceptive effects of intrathecal sildenafil in formalin-induced nociception was examined. Intrathecal catheters were inserted into the subarachnoid space of male Sprague-Dawley rats, and nociception was assessed using the formalin test, consisting of a subcutaneous injection of 50 μL of 5% formalin solution into the hind paw. We examined the effects of an alpha 1 adrenergic receptor antagonist (prazosin), an alpha 2 adrenergic receptor antagonist (yohimbine), a muscarinic acetylcholine receptor antagonist (atropine), and a nicotinic acetylcholine receptor antagonist (mecamylamine) on sildenafil-induced antinociception. Intrathecal sildenafil (3, 10, and 30 μg) suppressed, in a dose-dependent manner, formalin-induced flinching during phases 1 and 2 of the test. Intrathecal sildenafil (30 μg) could not show any effects against intrathecal prazosin (3 μg), yohimbine (10 μg), atropine (10 μg), and mecamylamine (10 μg) pretreatment during both phases of the formalin test. These results suggest that intrathecal sildenafil effectively attenuated the pain evoked by formalin injection. Additionally, spinal alpha 1, alpha 2, muscarinic and nicotinic receptors might play a role in sildenafil-induced antinociception.

Background: Oxytocin (OT) is one of the important paracrine factors that prostate synthesizes. OT maintains its resting tone and stimulates its contractile activity. However, the involvement of OT in modulating cell proliferation of the prostate is being investigated. In fact, alterations in OT concentrations accompany both benign prostatic hyperplasia/ hypertrophy and carcinoma of the prostate. The enzyme Insulin-regulated aminopeptidase (IRAP) is the main responsible of OT levels regulation through its catabolism. To date, the long-acting selective α1-adrenergic receptor antagonist doxazosin is widely used to the treatment of BPH. Thus, our aim was to analyze the effects of doxazosin on IRAP specific activity and its putative effects on prostate OT regulation and functions. Methods: Fifteen male Wistar rats were treated subcutaneously with 10 mg/Kg doxazosin during 15 days and fifteen controls were treated with the vehicle only. After the treatment period, prostate was removed to obtain soluble and membrane-bound fractions. Soluble and membrane-bound IRAP specific activities were assayed fluorometrically using leucyl-β-naphthylamide as substrate. Prostate OT content was assayed by enzyme immunoassay. Results: Doxazosin treatment significantly increased membrane-bound IRAP specific activity in rat prostate by 59.4%, whereas no changes were observed in the soluble fraction. Treatment with doxazosin also significantly increased OT concentration by 26.3%. Conclusions: In vivo administration of doxazosin to male rats modify both prostatic IRAP activity and OT levels. Because there is now evidence that OT plays a physiological role in the regulation of growth and muscular contractility within the gland, more attention should be paid to IRAP activity, which could represent a new target for the regulation of the functions of OT under physiological or pathological conditions such as BPH and prostate cancer.

Alpha-1-adrenergic receptors (α1-ARs) regulate coronary arterial blood flow by binding catecholamines, norepinephrine (NE), and epinephrine (EPI), causing vasoconstriction when the endothelium is disrupted. Among the three α1-AR subtypes (α1A, α1B, and α1D), the α1D subtype predominates in human epicardial coronary arteries and is functional in human coronary smooth muscle cells (SMCs). However, the presence or function of α1-ARs on human coronary endothelial cells (ECs) is unknown. Here we tested the hypothesis that human epicardial coronary ECs express functional α1-ARs. Cultured human epicardial coronary artery ECs were studied using quantitative real-time reverse transcription polymerase chain reaction, radioligand binding, immunoblot, and (3)H-thymidine incorporation. The α1B-subtype messenger ribonucleic acid (mRNA) was predominant in cultured human epicardial coronary ECs (90-95% of total α1-AR mRNA), and total α1-AR binding density in ECs was twice that in coronary SMCs. Functionally, NE and EPI through the α1B subtype activated extracellular signal-regulated kinase (ERK) in ECs, stimulated phosphorylation of EC endothelial nitric oxide synthase (eNOS), and increased deoxyribonucleic acid (DNA) synthesis. These results are the first to demonstrate α1-ARs on human coronary ECs and indicate that the α1B subtype is predominant. Our findings provide another potential mechanism for adverse cardiac effects of drug antagonists that nonselectively inhibit all three α1-AR subtypes.

Prediabetes is associated with impaired contraction‐evoked dilation of skeletal muscle arterioles, which may be due to increased sympathetic activity accompanying this early stage of diabetes disease. Herein, we sought to determine whether blunted contraction‐evoked vasodilation resulted from enhanced sympathetic neuropeptide Y1 receptor (Y1R) and alpha‐1 adrenergic receptor (α1R) activation. Using intravital video microscopy, second‐, third‐, and fourth‐order (2A, 3A, and 4A) arteriolar diameters were measured before and following electrical field stimulation of the gluteus maximus muscle (GM) in prediabetic (PD, Pound Mouse) and control (CTRL, c57bl6, CTRL) mice. Baseline diameter was similar between groups; however, single tetanic contraction (100 Hz; 400 and 800 msec) and sustained rhythmic contraction (2 and 8 Hz, 30 sec) evoked rapid onset vasodilation and steady‐state vasodilatory responses that were blunted by 50% or greater in PD versus CTRL. Following Y1R and α1R blockade with sympathetic antagonists BIBP3226 and prazosin, contraction‐evoked arteriolar dilation in PD was restored to levels observed in CTRL. Furthermore, arteriolar vasoconstrictor responses to NPY (10−13–10−8 mol/L) and PE (10−9–10−5 mol/L) were greater in PD versus CTRL at higher concentrations, especially at 3A and 4A. These findings suggest that contraction‐evoked vasodilation in PD is blunted by Y1R and α1R receptor activation throughout skeletal muscle arteriolar networks.

The neonatal ventral hippocampus (nVH) lesion in rats captures many features of schizophrenia at the levels of behavior and neurobiological markers. We have previously reported enhanced expression of alpha-1 adrenergic receptors (AR) in the prefrontal cortex (PFC) of postpubertal nVH-lesioned rats and proposed that enhanced alpha-1 AR signaling might participate in some of the behavioral abnormalities observed in the nVH-lesioned rats. To assess the components of alpha-1 adrenergic signaling in nVH-lesion rats, we examined prefrontal cortical expression of protein kinase C (PKC) subtypes by Western blotting and alpha-1 AR-stimulated PKC activity by in vitro enzyme assay in postpubertal animals. Neonatal VH-lesioned animals showed significantly increased expression of membrane-bound PKC-alpha and the phosphorylated form of PKC. Cytosolic PKC-beta II and PKC-gamma expression were found to be decreased in the PFC of lesioned animals with no change in the expression of PKC-beta I either in the cytosol or membrane. PKC activity assays showed an increase in basal PKC activity in the PFC slices of nVH-lesioned animals. Stimulation of alpha-1 adrenergic receptor with different concentrations of the agonist phenylephrine (PE), while increasing PKC activity in the sham-lesioned animals surprisingly decreased the activity in nVH-lesioned animals. Increased basal levels as well as activity of prefrontal PKC and its anomalous regulation by alpha-1 adrenergic receptors may participate in the cognitive and stress-induced behavioral alterations in nVH-lesioned animals.

Background Structural and functional alterations in the senescent heart have been associated with an activated sympathetic nervous system and a regional cardiac renin-angiotensin system. To date, however, limited information related to their expression alteration during the whole procress of growth and development has been reported. Objectives To examine the expression of alpha(1)-adrenergic receptor (α 1 -AR) and angiotensin II receptor (ATR) subtypes in the left ventricle of hearts from young adult, middle-aged, presenescent and senescent rats. Methods Semiquantitative reverse transcriptase polymerase chain reaction and Western blot were used to quantitate the messenger RNA and protein of α 1 -AR and ATR subtypes, respectively, in the left ventricles of three- (young adult), 12- (middle age), 18- (presenescent) and 24-month-old (senescent) Wistar rats. Results and conclusions α 1A -AR expression decreased gradually with age, and α 1D -AR expression was repressed in middle age and presenescence, while the expression of α 1B -AR remained unchanged during senescence. AT 1 R expression was unaffected by aging from young adulthood to presenescence, but exhibited a remarkable upregulation in senescence. There were no significant discrepancies of cardiac AT 2 R expression among the four age groups, but both messenger RNA and protein had a tendency to upregulate during aging. The results suggest that there are considerable changes of expression of cardiac α 1 -AR and ATR subtypes during growth and development. The change of cardiac α 1 -AR and ATR expression during aging is a protective response to senescence by keeping normal myocardial contractility, while the upregulation of AT 1 R and AT 2 R promotes age-related myocardium hypertrophy and cardiac remodelling.

Commercial antibodies are used widely to quantify and localize the alpha1-adrenergic receptor (AR) subtypes, alpha1A, alpha1B, and alpha1D. We tested ten antibodies, from abcam and Santa Cruz, using western blot with heart and brain tissue from wild-type (WT) mice and mice with systemic knockout (KO) of one or all three subtypes. We found that none of the antibodies detected a band in WT that was absent in the appropriate KO or in the KO that was null for all alpha1-ARs (ABDKO). We conclude that the antibodies we tested are not specific for alpha1-ARs. These results raise caution with prior studies using these reagents. For now, competition radioligand binding is the only reliable approach to quantify the alpha1-AR subtype proteins. Receptor protein localization remains a challenge.

The radial migration is an important process in the development of the cerebral cortex. Earlier studies have reported that classical neurotransmitters such as L-dopamine and L-adrenaline regulate the proliferation of neural progenitor cells. We examined whether L-dopamine and L-adrenaline regulate cell migration, using embryonic neural progenitor cells from mouse embryonic telencephalon in vitro. In this study, we showed that dopamine D1 agonist induces cell migration of embryonic neural progenitor cells. In addition, we have demonstrated that L-adrenaline induces cell migration of embryonic neural progenitor cells, mediated through the activation of alpha-1 adrenergic receptors. Our results suggest that alpha-1 adrenergic receptor and dopamine D1 receptor stimulations in neural progenitor cells are the important process for embryonic brain development, respectively.

Background To study the influence of the changes in the α1-adrenergic receptor and NGF/ProNGF pathway on the diabetic urethral function. Methods A total of 20 female Wistar rats were divided into two groups equally at random. Urethral function was examined by recordings of bladder pressure and urethral perfusion pressure (UPP). The expression of α1-adrenergic receptor in the urethra was measured via RT-qPCR and ELISA method. The expression of nerve growth factor (NGF) in the urethra was measured via RT-qPCR and ELISA method. The expression of proNGF, P75NTR and sortilin in the urethra was measured by western blotting. Results The lowest urethral pressure (UPP nadir) during urethral relaxation was higher in diabetic rats. The UPP nadir and baseline UPP in diabetic rats was significantly decreased by intravenous administration of the α1-adrenoceptor antagonist (tamsulosin). The α1a and α1d adrenergic receptor in the urethra of the diabetic group was significantly increased via RT-qPCR and western blotting (P0.05). Conclusions The increase in the expression of α1-adrenoceptor and changes of the NGF/ProNGF pathway in the diabetic urethral was a possible mechanism of the diabetic urethral dysfunction.

Objectives To elucidate the in vitro and ex vivo effects of saw palmetto extract (SPE) on autonomic receptors in the rat lower urinary tract. Methods The in vitro binding affinities for alpha 1-adrenergic, muscarinic, and purinergic receptors in the rat prostate and bladder were measured by radioligand binding assays. Rats received vehicle or SPE (0.6 to 60 mg/kg/day) orally for 4 weeks, and alpha 1-adrenergic and muscarinic receptor binding in tissues of these rats were measured. Results Saw palmetto extract inhibited specific binding of [ 3 H]prazosin and [N-methyl- 3 H]scopolamine methyl chloride (NMS) but not alpha, beta-methylene adenosine triphosphate [2,8- 3 H]tetrasodium salt in the rat prostate and bladder. The binding activity of SPE for muscarinic receptors was four times greater than that for alpha 1-adrenergic receptors. Scatchard analysis revealed that SPE significantly reduced the maximal number of binding sites (B max ) for each radioligand in the prostate and bladder under in vitro condition. Repeated oral administration of SPE to rats brought about significant alteration in B max for prostatic [ 3 H]prazosin binding and for bladder [ 3 H]NMS binding. Such alteration by SPE was selective to the receptors in the lower urinary tract. Conclusions Saw palmetto extract exerts significant binding activity on autonomic receptors in the lower urinary tract under in vitro and in vivo conditions.

Blood flow to skeletal muscle is regulated in part by stimulation of vascular adrenergic receptors (ARs), which are expressed in several subtypes. The species and tissue distribution of these recep...

1. Centrally acting imidazoline antihypertensive agents clonidine and moxonidine also act peripherally to contract blood vessels. While these agents act at both I(1)-imidazoline and alpha 2 adrenergic receptors centrally, the receptor types by which they mediate contraction require further definition. We therefore characterized the receptor subtype by which these agents mediate contraction of proximal rat-tail artery. 2. Dose-response curves were determined for phenylephrine and for several imidazoline ligands, using endothelium denuded, isolated ring segments, of tail arteries from adult male Sprague-Dawley rats. Ring segments were mounted on a force transducer with platinum wires and immersed in a tissue bath containing Krebs solution, to which drugs could be added. Signals were digitized and recorded by a computer. 3. Tail artery contractions expressed as a percent of contraction to 106 mM potassium were phenylephrine (96%), moxonidine (88%), clonidine (52%), and UK14304 (30%). Neither rilmenidine nor harmane caused contraction. Contraction of tail artery to moxonidine or clonidine could be blocked by alpha 1 antagonist urapidil or prazosin, and also by alpha 1A subtype selective antagonist WB4101. Schild plots were generated and a calculated pA2 value of 9.2 for prazosin in the presence of clonidine confirms clonidine as an agonist at alpha 1A receptors in proximal segments of rat-tail artery. 4. Our work suggests that clonidine and moxonidine are promiscuous compounds at micromolar concentrations and that harmane and rilmenidine are more selective compounds for in vivo imidazoline research.

The hypothalamic paraventricular nucleus (PVN) neurons that project to the spinal intermediolateral cell column and brainstem are important for the control of sympathetic outflow. Stimulation of alpha(1) adrenergic receptors in the PVN increases sympathetic outflow, but the cellular mechanisms remain unclear. In this study, we determined the role of alpha(1) adrenergic receptors in the regulation of glutamatergic and GABAergic synaptic inputs to spinally projecting PVN neurons. Whole-cell and cell-attached patch-clamp recordings were performed on retrogradely labeled PVN-spinal neurons in rat brain slices. Bath application of 10 to 100 microM phenylephrine, an alpha(1) adrenergic receptor agonist, significantly increased the frequency of spontaneous excitatory postsynaptic currents in a concentration-dependent manner. This effect was blocked by the alpha (1)adrenergic receptor antagonists prazosin or corynanthine. Phenylephrine also significantly increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) but not the amplitude and decay constant of mEPSCs. Furthermore, activation of alpha(1) adrenergic receptors with phenylephrine or cirazoline significantly decreased the frequency of spontaneous inhibitory postsynaptic currents and miniature inhibitory postsynaptic currents, and this effect also was blocked by corynanthine. In addition, 50 microM phenylephrine significantly increased the firing rate of 13 labeled PVN neurons from 3.16 +/- 0.42 to 5.83 +/- 0.65 Hz. However, phenylephrine failed to increase the firing of most labeled PVN neurons in the presence of GABA(A) and ionotropic glutamate receptor antagonists. Thus, these data suggest that activation of alpha (1)adrenergic receptors increases the excitability of PVN presympathetic neurons primarily through augmentation of glutamatergic tone and attenuation of GABAergic inputs.

Aging humans and rats have a reduced renal vascular constriction response to stress, change in posture, or exercise. In this study, renal interlobar arteries from 9- (intermediate age) to 15-month-old (aging) male Wistar rats constricted less to alpha-adrenergic agonists than those of 4-month-old (young adult) rats. The reduced contraction to A61603 (alpha 1 A agonist) was similar to that to norepinephrine and phenylephrine. Therefore, it appears that the reduction in constriction is primarily related to alpha 1 A receptor stimulation. GeneChip microarray hybridization analysis of the interlobar arteries with the RAE 230A GeneChip indicated that there were no significant differences in gene expression for alpha 1 A/C, 1B, or 1D receptors between 4-month-old (young adult) and 1-year-old (aging) male Wistar rats. Competitive binding experiments (prazosin) revealed that maximal binding (Bmax, fmol/mg protein) of the alpha 1 receptors of interlobar arteries was reduced 25% by 10 months of age and 50% by 18+ months of age. Alpha 1 receptor-induced arterial constriction and prazosin binding were both down-regulated. The loss of receptor-initiated constriction likely includes down-regulation of maximum agonist binding by alpha 1 adrenergic receptors.Key words: kidney, stress, blood flow, male vs. female, GeneChip array, prazosin.

D. T. McCloskey, D. G. Rokosh, T. D. O'Connell, E. C. Keung, P. C. Simpson and A. J. Baker. α1-Adrenoceptor Subtypes Mediate Negative Inotropy in Myocardium from α1A/C-Knockout and Wild Type Mice. Journal of Molecular and Cellular Cardiology (2002) 34, 1007–1017. Cardiac α1-adrenoceptors (AR) have two predominant subtypes (α1A-AR and α1B-AR) however, their roles in regulating contraction are unclear. We determined the effects of stimulating α1A-AR (using the subtype-selective agonist A61603) and α1B-AR (using a gene knockout mouse lacking α1A-AR) separately, and together (using phenylephrine) on Ca2+ transients, intracellular pH, and contraction of mouse cardiac trabeculae. Stimulation of α1-AR subtypes separately or together caused a triphasic contractile response. After a transient (≈3%) force rise (phase 1), force declined markedly (phase 2), then partially recovered (phase 3). In phase 2, the force decline (% of initial) with combined α1A-AR plus α1B-AR stimulation (50±3%) was more than with separate subtype stimulation (P