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Made available in DSpace on 2021-06-25T15:01:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Pro-Reitoria de Pesquisa -Sao Paulo State University The mechanisms by which changes in intracranial pressure (ICP) occur during hypertension are unclear. The experimental 2K1C (2-kidney, 1-clip) hypertension is a model characterized by sympathetic and renin-angiotensin system overactivation in which ICP still needs investigation. In the present study, we analyzed ICP alterations during the development of 2K1C hypertension using invasive and noninvasive ICP recording methods. We also tested the importance of AT1R (angiotensin II type 1 receptor) activation for the ICP changes and investigated the integrity of the blood-brain barrier within central cardioregulatory nuclei in 2K1C hypertensive rats. 2K1C hypertension was induced in 6-week-old male rats (150 g). In the fourth week of 2K1C hypertension induction, when mean arterial pressure reached 162 +/- 2 mm Hg, ICP significantly increased, ICP pulse waveforms changed, increasing the ratio between the two peaks (P2/P1 ratio) of the ICP waveform. In the third week of 2K1C hypertension induction, blood-brain barrier disruption was detected within the hypothalamic paraventricular nucleus, rostral ventrolateral medulla, and nucleus tractus solitarius. In the sixth week, intravenous losartan (AT1R antagonist) or the vasodilator hydralazine acutely reduced arterial pressure to normotensive levels. Losartan, but not hydralazine, partially reduced the increase of ICP and P2/P1 ratio in hypertensive rats. These results show significant changes in ICP in 2K1C hypertensive rats and suggest that AT1R activation may contribute to elevated ICP during hypertension-an effect possibly intensified by the blood-brain barrier disruption in important central cardioregulatory nuclei in renovascular hypertensive animals. Sao Paulo State Univ, Sch Dent Araraquara, Dept Physiol & Pathol, Rua Humaita 1680, BR-14801 Araraquara, SP, Brazil Auburn Univ, Dept Anat Physiol & Pharmacol, Coll Vet Med, Auburn, AL 36849 USA Auburn Univ, Ctr Neurosci Res Initiat, Auburn, AL 36849 USA Sao Paulo State Univ, Sch Dent Araraquara, Dept Physiol & Pathol, Rua Humaita 1680, BR-14801 Araraquara, SP, Brazil CAPES: CAPES PROEX-0487 FAPESP: 2015/23467-7

Made available in DSpace on 2020-12-12T02:49:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Obesity is a global epidemic in developed countries accounting for many of the metabolic and cardiorespiratory morbidities that occur in adults. These morbidities include type 2 diabetes, sleepdisordered breathing (SDB), obstructive sleep apnea, chronic intermittent hypoxia, and hypertension. Leptin, produced by adipocytes, is a master regulator of metabolism and of many other biological functions including central and peripheral circuits that control breathing. By binding to receptors on cells and neurons in the brainstem, hypothalamus, and carotid body, leptin links energy and metabolism to breathing. In this comprehensive article, we review the central and peripheral locations of leptin’s actions that affect cardiorespiratory responses during health and disease, with a particular focus on obesity, SDB, and its effects during early development. Obesityinduced hyperleptinemia is associated with centrally mediated hypoventilation with decrease CO2 sensitivity. On the other hand, hyperleptinemia augments peripheral chemoreflexes to hypoxia and induces sympathoexcitation. Thus, “leptin resistance” in obesity is relative. We delineate the circuits responsible for these divergent effects, including signaling pathways. We review the unique effects of leptin during development on organogenesis, feeding behavior, and cardiorespiratory responses, and how undernutrition and overnutrition during critical periods of development can lead to cardiorespiratory comorbidities in adulthood. We conclude with suggestions for future directions to improve our understanding of leptin dysregulation and associated clinical diseases and possible therapeutic targets. Lastly, we briefly discuss the yin and the yang, specifically the contribution of relative adiponectin deficiency in adults with hyperleptinemia to the development of metabolic and cardiovascular disease. Division of Neonatology Department of Pediatrics The Hospital for Sick Children CEDOC NOVA Medical School Faculdade de Ciências Médicas Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP) Faculty of Medicine University of Toronto Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP)

Made available in DSpace on 2020-12-12T02:42:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Intracerebroventricular (icv) injection of hydrogen peroxide (H2O2) or the increase of endogenous H2O2 centrally produced by catalase inhibition with 3-amino-1,2,4-triazole (ATZ) injected icv reduces the pressor responses to central angiotensin II (ANG II) in normotensive rats. In the present study, we investigated the changes in the arterial pressure and in the pressor responses to ANG II icv in spontaneously hypertensive rats (SHRs) and 2-kidney, 1-clip (2K1C) hypertensive rats treated with H2O2 injected icv or ATZ injected icv or intravenously (iv). Adult male SHRs or Holtzman rats (n = 5–10/group) with stainless steel cannulas implanted in the lateral ventricle were used. In freely moving rats, H2O2 (5 μmol/1 μl) or ATZ (5 nmol/1 μl) icv reduced the pressor responses to ANG II (50 ng/1 µl) icv in SHRs (11 ± 3 and 17 ± 4 mmHg, respectively, vs. 35 ± 6 mmHg) and 2K1C hypertensive rats (3 ± 1 and 16 ± 3 mmHg, respectively, vs. 26 ± 2 mmHg). ATZ (3.6 mmol/kg of body weight) iv alone or combined with H2O2 icv also reduced icv ANG II-induced pressor response in SHRs and 2K1C hypertensive rats. Baseline arterial pressure was also reduced (−10 to −15 mmHg) in 2K1C hypertensive rats treated with H2O2 icv and ATZ iv alone or combined and in SHRs treated with H2O2 icv alone or combined with ATZ iv. The results suggest that exogenous or endogenous H2O2 acting centrally produces anti-hypertensive effects impairing central pressor mechanisms activated by ANG II in SHRs or 2K1C hypertensive rats. Department of Physiology and Pathology Dentistry School São Paulo State University (UNESP) School of Medicine Pharmacy and Biomedicine Pontifical Catholic University of Goias Department of Physiology and Pathology Dentistry School São Paulo State University (UNESP)

Made available in DSpace on 2022-04-29T08:46:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-05-01 Booz Allen Foundation Recent evidence has suggested that the carotid bodies might act as immunological sensors, detecting pro-inflammatory mediators and signalling to the central nervous system, which, in turn, orchestrates autonomic responses. Here, we confirmed that the TNF-α receptor type I is expressed in the carotid bodies of rats. The systemic administration of TNF-α increased carotid body afferent discharge and activated glutamatergic neurons in the nucleus tractus solitarius (NTS) that project to the rostral ventrolateral medulla (RVLM), where many pre-sympathetic neurons reside. The activation of these neurons was accompanied by an increase in splanchnic sympathetic nerve activity. Carotid body ablation blunted the TNF-α-induced activation of RVLM-projecting NTS neurons and the increase in splanchnic sympathetic nerve activity. Finally, plasma and spleen levels of cytokines after TNF-α administration were higher in rats subjected to either carotid body ablation or splanchnic sympathetic denervation. Collectively, our findings indicate that the carotid body detects circulating TNF-α to activate a counteracting sympathetic anti-inflammatory mechanism. Department of Physiology and Pathology School of Dentistry São Paulo State University, São Paulo Department of Neurosciences and Behavior Ribeirão Preto Medical School University of São Paulo, São Paulo Department of Pharmacology Ribeirão Preto Medical School University of São Paulo, São Paulo Department of Physiology Ribeirão Preto Medical School University of São Paulo, São Paulo Department of Physiology and Pathology School of Dentistry São Paulo State University, São Paulo Booz Allen Foundation: 2015/23467-7 Booz Allen Foundation: 2019/11196-0 Booz Allen Foundation: PROPE-UNESP

Made available in DSpace on 2020-12-12T02:26:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-01 Intracerebroventricular (icv) injection of hydrogen peroxide (H2O2), a reactive oxygen species, or the blockade of catalase (enzyme that degrades H2O2 into H2O and O2) with icv injection of 3-amino-1,2,4-triazole (ATZ) reduces the pressor effects of angiotensin II also injected icv. In the present study, we investigated the effects of ATZ injected icv or intravenously (iv) on the pressor responses induced by icv injections of the cholinergic agonist carbachol, which similar to angiotensin II induces pressor responses that depend on sympathoexcitation and vasopressin release. In addition, the effects of H2O2 icv on the pressor responses to icv carbachol were also tested to compare with the effects of ATZ. Normotensive non-anesthetized male Holtzman rats (280–300 g, n = 8–9/group) with stainless steel cannulas implanted in the lateral ventricle were used. Previous injection of ATZ (5 nmol/1 μl) or H2O2 (5 μmol/1 μl) icv similarly reduced the pressor responses induced by carbachol (4 nmol/1 μl) injected icv (13 ± 4 and 12 ± 4 mmHg, respectively, vs. vehicle + carbachol: 30 ± 5 mmHg). ATZ (3.6 mmol/kg of body weight) injected iv also reduced icv carbachol-induced pressor responses (21 ± 2 mmHg). ATZ icv or iv and H2O2 icv injected alone produced no effect on baseline arterial pressure. The treatments also produced no significant change of heart rate. The results show that ATZ icv or iv reduced the pressor responses to icv carbachol, suggesting that endogenous H2O2 acting centrally inhibits the pressor mechanisms (sympathoactivation and/or vasopressin release) activated by central cholinergic stimulation. Department of Physiology and Pathology Dentistry School São Paulo State University (UNESP) Department of Physiology and Pathology Dentistry School São Paulo State University (UNESP)

NEW FINDINGS What is the central question of this study? Adrenomedullin in the rostral ventrolateral medulla (RVLM) increases sympathetic activity; given that adrenomedullin is released during hypoxia, what are the effects of its agonism and antagonism in the RVLM after chronic intermitent hypoxia (CIH) exposure? What is the main finding and its importance? CIH exposure sensitizes adrenomedullin-dependent mechanisms in the RVLM, supporting its role as a sympathoexcitatory neuromodulator. A novel mechanism was identified for the generation of sympathetic overdrive and hypertension associated with hypoxia, providing potential guidance on new therapeutic approaches for controlling sympathetic hyperactivity in diseases such as sleep apnoea and neurogenic hypertension. ABSTRACT Adrenomedullin in the rostral ventrolateral medulla (RVLM) has been shown to increase sympathetic activity whereas the antagonism of its receptors inhibited this autonomic activity lowering blood pressure in conditions of hypertension. Given that hypoxia is a stimulant for releasing adrenomedullin, we hypothesized that the presence of this peptide in the RVLM associated with chronic intermittent hypoxia (CIH) would cause sympathetic overdrive. Juvenile male rats (50-55 g) submitted to CIH (6% oxygen every 9 min, 8 h day-1 for 10 days) were studied in an arterially perfused in situ preparation where sympathetic activity was recorded. In control rats (n = 6), exogenously applied adrenomedullin in the RVLM raised baseline sympathetic activity when combined with episodic activation of peripheral chemoreceptors (KCN 0.05%, 5 times every 5 min). This sympathoexcitatory response was markedly amplified in rats previously exposed to CIH (n = 6). The antagonism of adrenomedullin receptors in the RVLM caused a significant reduction in sympathetic activity in the CIH group (n = 7), but not in controls (n = 8). The transient reflex-evoked sympathoexcitatory response to peripheral chemoreceptor stimulation was not affected by either adrenomedullin or adrenomedullin receptor antagonism in the RVLM of control and CIH rats. Our findings indicate that CIH sensitizes the sympathoexcitatory networks within the RVLM to adrenomedullin, supporting its role as an excitatory neuromodulator when intermittent hypoxia is present. These data reveal novel state-dependent mechanistic insights into the generation of sympathetic overdrive and provide potential guidance on possible unique approaches for controlling sympathetic discharge in diseases such as sleep apnoea and neurogenic hypertension.

A high-fat diet (HFD) induces an increase in arterial pressure and a decrease in baroreflex function, which may be associated with increased expression of angiotensin type 1 receptor (AT1R) and pro-inflammatory cytokine genes and reduced expression of the angiotensin type 2 receptor (AT2R) gene within the nucleus of the solitary tract (NTS), a key area of the brainstem involved in cardiovascular control. Thus, in the present study, we evaluated the changes in arterial pressure and gene expression of components of the renin-angiotensin system (RAS) and neuroinflammatory markers in the NTS of rats fed a HFD and treated with either an AT1R blocker or with virus-mediated AT2R overexpression in the NTS. Male Holtzman rats (300-320 g) were fed either a standard rat chow diet (SD) or HFD for 6 weeks before commencing the tests. AT1R blockade in the NTS of HFD-fed rats attenuated the increase in arterial pressure and the impairment of reflex bradycardia, whereas AT2R overexpression in the NTS only improved the baroreflex function. The HFD also increased the hypertensive and decreased the protective axis of the RAS and was associated with neuroinflammation within the NTS. The expression of angiotensin-converting enzyme and neuroinflammatory components, but not AT1R, in the NTS was reduced by AT2R overexpression in this site. Based on these data, AT1R and AT2R in the NTS are differentially involved in the cardiovascular changes induced by a HFD. Chronic inflammation and changes in the RAS in the NTS may also account for the cardiovascular responses observed in HFD-fed rats.

Made available in DSpace on 2019-10-06T16:55:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Central cholinergic activation stimulates water intake, but also NaCl intake when the inhibitory mechanisms are blocked with injections of moxonidine (α2 adrenergic/imidazoline agonist) into the lateral parabrachial nucleus (LPBN). In the present study, we investigated the involvement of central M1 and M2 muscarinic receptors on NaCl intake induced by pilocarpine (non-selective muscarinic agonist) intraperitoneally combined with moxonidine into the LPBN or by muscimol (GABAA agonist) into the LPBN. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN and in the lateral ventricle were used. Pirenzepine (M1 muscarinic antagonist, 1 nmol/1 μl) or methoctramine (M2 muscarinic antagonist, 50 nmol/1 μL) injected intracerebroventricularly (i.c.v.) reduced 0.3 M NaCl and water intake in rats treated with pilocarpine (0.1 mg/100 g of body weight) injected intraperitoneally combined with moxonidine (0.5 nmol/0.2 μL) into the LPBN. In rats treated with muscimol (0.5 nmol/0.2 μL) into the LPBN, methoctramine i.c.v. also reduced 0.3 M NaCl and water intake, however, pirenzepine produced no effect. The results suggest that M1 and M2 muscarinic receptors activate central pathways involved in the control of water and sodium intake that are under the influence of the LPBN inhibitory mechanisms. Department of Physiology and Pathology School of Dentistry São Paulo State University - UNESP Department of Physiology and Pathology School of Dentistry São Paulo State University - UNESP

Made available in DSpace on 2021-06-25T15:07:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Renovascular hypertension is a type of secondary hypertension caused by renal artery stenosis, leading to an increase in the renin-angiotensin-aldosterone system (RAAS). Two-kidney, 1-clip (2K1C) is a model of renovascular hypertension in which rats have an increased sodium intake induced by water deprivation (WD), a common situation found in the nature. In addition, a high-sodium diet in 2K1C rats induces glomerular lesion. Therefore, the purpose of this study was to investigate whether angiotensin II (ANG II) and/or aldosterone participates in the increased sodium intake in 2K1C rats under WD. In addition, we also verified if central AT1 and mineralocorticoid receptor blockade would change the high levels of arterial pressure in water-replete (WR) and WD 2K1C rats, because blood pressure changes can facilitate or inhibit water and sodium intake. Finally, possible central areas activated during WD or WD followed by partial rehydration (PR) in 2K1C rats were also investigated. Male Holtzman rats (150-180 g) received a silver clip around the left renal artery to induce renovascular hypertension. Six weeks after renal surgery, a stainless-steel cannula was implanted in the lateral ventricle, followed by 5-7 days of recovery before starting tests. Losartan (AT1 receptor antagonist) injected intracerebroventricularly attenuated water intake during the thirst test. Either icv losartan or RU28318 (mineralocorticoid receptor antagonist) reduced 0.3 M NaCl intake, whereas the combination of losartan and RU28318 icv totally blocked 0.3 M NaCl intake induced by WD in 2K1C rats. Losartan and RU28318 icv did not change hypertension levels of normohydrated 2K1C rats, but reduced the increase in mean arterial pressure (MAP) produced by WD. c-Fos expression increased in the lamina terminalis and in the NTS in WD condition, and increased even more after WD-PR. These results suggest the participation of ANG II and aldosterone acting centrally in the enhanced sodium intake in WD 2K1C rats, and not in the maintenance of hypertension in satiated and fluid-replete 2K1C rats. Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil FAPESP: 2015/234.677 CNPq: 425.586/2016-2 CNPq: 308.099/2017-6 CAPES: 001

Made available in DSpace on 2021-06-25T10:17:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Hypercapnia promotes an increase in pulmonary ventilation due to the stimulation of brainstem chemosensory cells that are connected to the respiratory network. Among these cells are the raphe serotonergic neurons which widely send projections to distinct central respiratory compartments. Nevertheless, the physiological role of specific raphe serotonergic projections to other chemosensitive sites on the emergence of hypercapnia ventilatory response in vivo still remains to be elucidated. Here we investigated whether the ventilatory response to hypercapnia requires serotonergic inputs to the chemosensitive cells of the retrotrapezoid nucleus (RTN) in the ventrolateral medulla. To test this, pulmonary ventilation was evaluated under baseline conditions and during hypercapnia (7% CO2) in unanesthetized juvenile Holtzman rats (60–90 g) that received bilateral microinjections of either vehicle (control) or anti-SERT-SAP (0.1 mM, 10 pmol/100 nl) toxin in the RTN to retrogradely destroy serotonergic afferents to this region. Fifteen days after microinjections, baseline ventilation was not different between anti-SERT-SAP (n = 8) and control animals (n = 9). In contrast, the ablation of RTN-projecting serotonergic neurons markedly attenuated the hypercapnia-induced increase in respiratory frequency which was correlated with reduced numbers of serotonergic neurons in the raphe obscurus and magnus, but not in the raphe pallidus. The increase in tidal volume during hypercapnia was not significantly affected by anti-SERT-SAP microinjections in the RTN. Our data indicate that serotoninergic neurons that send projections to the RTN region are required for the processing of ventilatory reflex response during exposure to high CO2 in unanesthetized conditions. Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP) Department of Physiology and Biophysics. Institute of Biological Sciences Federal University of Minas Gerais (ICB/UFMG) Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP) CNPq: 132363/2018-6 FAPESP: 2013/17251-6 FAPESP: 2018/04439-0 FAPESP: 2018/21000-2 CNPq: 310331/2017-0 CNPq: 403769/2016-7 CNPq: 408950/2018-8

Made available in DSpace on 2021-06-26T04:30:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-17 Coordination for the Improvement of Higher Education Personnel National Council for Scientific and Technological Development Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) New Findings What is the central question of this study? This study presents a new model for studying the rapid onset of severe, acute hyperkalaemia in rats with intact kidney function by administering an intragastric KCl load. What is the main finding and its importance? This new model of intragastric KCl load produces a reliable and reproducible model for studying the rapid onset of severe, acute hyperkalaemia in rats with intact kidney function. We report unprecedented rapid changes (30 min) in ECG, blood pressure and various arterial blood analyses with this new model, providing a solid foundation for future experiments in this field. A variety of animal models have been proposed to study hyperkalaemia, but most of them have meaningful limitations when the goal is to study the effect of potassium overload on healthy kidneys. In this study, we aimed to introduce a new approach for induction of hyperkalaemia in a reliable and reproducible animal model. We used intragastric administration of potassium chloride [KCl 2.3 M, 10 ml/(kg body weight)] to male Holtzman rats (300-350 g) to induce hyperkalaemia. The results showed that this potassium load can temporarily overwhelm the renal and extrarenal handling of this ion, causing an acute and severe hyperkalaemia that can be useful to study the effect of potassium imbalance in a variety of scenarios. Severe hyperkalaemia (>8 meqiv/l) and very profound ECG alterations, characterized by lengthening waves and intervals, were seen as early as 30 min after intragastric administration of KCl in rats. In addition, a transient increase in arterial blood pressure and time-dependent bradycardia were also seen after the KCl administration. No metabolic acidosis was present in the animals, and the potassium ion did not increase proportionally to chloride ion in the blood, leading to an increased anion gap. In conclusion, the results suggest that intragastric KCl loading is a reliable model to promote rapid and severe hyperkalaemia that can be used for further research on this topic. Sao Paulo State Univ, Araraquara Sch Dent, Araraquara, SP, Brazil Univ Sao Paulo, Ribeirao Preto Med Sch, Ribeirao Preto, SP, Brazil Sao Paulo State Univ, Araraquara Sch Dent, Araraquara, SP, Brazil FAPESP: 2015/23467-7 FAPESP: 33009015 FAPESP: 2018/02194-0 FAPESP: 305096/2014-1)

Made available in DSpace on 2020-12-12T02:38:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The two kidney-one clip (2K1C) renovascular hypertension depends on the renin-angiotensin system and sympathetic overactivity. The maintenance of 2K1C hypertension also depends on inputs from the carotid bodies (CB), which when activated stimulate the respiratory activity. In the present study, we investigated the importance of CB afferent activity for the ventilatory responses in 2K1C hypertensive rats and for phrenic and hypoglossal activities in in situ preparations of normotensive rats treated with angiotensin II. Silver clips were implanted around the left renal artery of male Holtzman rats (150 g) to induce renovascular hypertension. Six weeks after clipping, hypertensive 2K1C rats showed, in conscious state, elevated resting tidal volume and minute ventilation compared with the normotensive group. 2K1C rats also presented arterial alkalosis, urinary acidification, and amplified hypoxic ventilatory response. Carotid body removal (CBR), 2 wk before the experiments (4th week after clipping), significantly reduced arterial pressure and pulmonary ventilation in 2K1C rats but not in normotensive rats. Intra-arterial administration of angiotensin II in the in situ preparation of normotensive rats increased phrenic and hypoglossal activities, responses that were also reduced after CBR. Results show that renovascular hypertensive rats exhibit increased resting ventilation that depends on CB inputs. Similarly, angiotensin II increases phrenic and hypoglossal activities in in situ preparations of normotensive rats, responses that also depend on CB inputs. Results suggest that mechanisms that depend on CB inputs in renovascular hypertensive rats or during angiotensin II administration in normotensive animals increase respiratory drive. Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP), Rua Humaitá, 1680 Center for Neuroscience and Cardiovascular Research Department of Physiological Sciences Biological Sciences Institute Federal University of Goiás Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP), Rua Humaitá, 1680 FAPESP: 2013/17.251-6 FAPESP: 2014/01159-6 FAPESP: 2015/23467-7 CNPq: 310331/ 2017-0 CNPq: 449392/2014-7

Made available in DSpace on 2019-10-06T16:00:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Breathing disorders are commonly observed in association with obesity. Here we tested whether high-fat diet (HFD) impairs the chemoreflex ventilatory response. Male Holtzman rats (300–320 g) were fed with standard chow diet (SD) or HFD for 12 weeks. Then, tidal volume (V T ), respiratory frequency (f R ) and pulmonary ventilation (V E ) were determined in conscious rats during basal condition, hypercapnia (7% or 10% CO 2 ) or hypoxia (7% O 2 ). The mean arterial pressure (MAP), heart rate (HR) and baroreflex sensitivity were also evaluated in conscious rats. A group of anesthetized rats was used for the measurements of the activity of inspiratory (diaphragm) and expiratory (abdominal) muscles under the same gas conditions. Baseline f R , V T and V E were similar between SD and HFD rats. During hypercapnia, the increase of f R was exacerbated in conscious HFD rats (60 ± 3, vs. SD: 47 ± 3 Δ breaths.min −1 , P < 0.05). In anesthetized rats, hypercapnia strongly increased abdominal muscle activity in HFD group (238 ± 27, vs. basal condition: 100 ± 0.3%; P < 0.05), without significant change in SD group (129 ± 2.1, vs. basal condition: 100 ± 0.8%; P = 0.34). The ventilatory responses to hypoxia were similar between groups. In conscious HFD rats, MAP and HR were elevated and the baroreflex function was impaired (P < 0.05). These data demonstrated that 12 weeks of HFD exaggerate the ventilatory response activated by hypercapnia. The mechanisms involved in these responses need more investigation in future studies. Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP) Department of Clinical Analysis School of Pharmaceutical Sciences UNESP Department of Physiological Sciences Biological Sciences Center Federal University of Santa Catarina (UFSC), Rua Roberto Sampaio Gonzaga s/n, Trindade Department of Physiology and Pathology School of Dentistry São Paulo State University (UNESP) Department of Clinical Analysis School of Pharmaceutical Sciences UNESP FAPESP: 2013/13118-0 FAPESP: 2013/14850-6 FAPESP: 2013/17251-6 CAPES: 20131972 FAPESP: 2015/234677 CNPq: 304873/2014-4 CNPq: 310331/2017-0 CNPq: 425586/2016-2

NEW FINDINGS What is the central question of this study? Does carotid body input contribute to the hyperosmotic responses? What is the main finding and its importance? The response to NaCl overload is sympathorespiratory excitation. Eliminating the carotid body input reduced sympathoexcitation but did not affect the increase in phrenic burst frequency, whereas eliminating the hypothalamus prevented the tachypnoea and sympathoexcitation. We conclude that the carotid body inputs are essential for the full expression of the sympathetic activity during acute NaCl overload, whereas the tachypnoea depends on hypothalamic mechanisms. ABSTRACT Acute salt excess activates central osmoreceptors, which trigger an increase in sympathetic and respiratory activity. The carotid bodies also respond to hyperosmolality of the extracellular compartment, but their contribution to the sympathoexcitatory and ventilatory responses to NaCl overload remains unknown. To evaluate their contribution to acute NaCl overload, we recorded thoracic sympathetic (tSNA), phrenic (PNA) and carotid sinus nerve activities in decorticate in situ preparations of male Holtzman rats (60-100 g) while delivering intra-arterial infusions of hyperosmotic NaCl (0.17, 0.3, 0.7, 1.5 and 2.0 mol l-1 ; 200 μl infusion over 25-30 s, with a 10 min time interval between solutions) or mannitol (0.3, 0.5, 1.0, 2.7 and 3.8 mol l-1 ) progressively. The cumulative infusions of hyperosmotic NaCl increased the perfusate osmolality to 341 ± 5 mosmol (kg water)-1 and elicited an immediate increase in PNA and tSNA (n = 6, P < 0.05) in sham-denervated rats. Carotid body removal attenuated sympathoexcitation (n = 5, P < 0.05) but did not affect the tachypnoeic response. A precollicular transection disconnecting the hypothalamus abolished the sympathoexcitatory and tachypnoeic responses to NaCl overload (n = 6, P < 0.05). Equi-osmolar infusions of mannitol did not alter the PNA and tSNA in sham-denervated rats (n = 5). Sodium chloride infusions increased carotid sinus nerve activity (n = 10, P < 0.05), whereas mannitol produced negligible changes (n = 5). The results indicate that carotid bodies are activated by acute NaCl overload, but not by mannitol. We conclude that the carotid bodies contribute to the increased sympathetic activity during acute NaCl overload, whereas the ventilatory response is mainly mediated by hypothalamic mechanisms.

Made available in DSpace on 2018-12-11T17:36:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-05-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The activation of GABA, opioid or α2 adrenergic mechanisms in the lateral parabrachial nucleus (LPBN) facilitates hypertonic NaCl intake in rats. In the present study, we combined opioid or α2 adrenergic antagonists with GABA agonists into the LPBN in order to investigate if NaCl intake caused by GABAergic activation in normohydrated rats depends on opioid or α2-adrenergic mechanisms in this area. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. Bilateral injections of muscimol or baclofen (GABAA and GABAB agonists, respectively, 0.5 nmol/0.2 μl) into the LPBN induced strong ingestion of 0.3 M NaCl (45.8 ± 7.3 and 21.8 ± 4.8 ml/240 min, respectively) and water intake (22.7 ± 3.4 and 6.6 ± 2.5 ml/240 min, respectively). Naloxone (opioid antagonist, 150 nmol/0.2 μl) into the LPBN abolished 0.3 M NaCl and water intake to muscimol (2.0 ± 0.6 and 0.9 ± 0.2 ml/240 min, respectively) or baclofen (2.3 ± 1.1 and 0.8 ± 0.4 ml/240 min, respectively). RX 821002 (α2 adrenoceptor antagonist, 10 nmol/0.2 μl) into the LPBN reduced 0.3 M NaCl intake induced by the injections of muscimol or baclofen (26.6 ± 8.0 and 10.1 ± 4.9 ml/240 min, respectively). RX 821002 reduced water intake induced by muscimol (7.7 ± 2.9 ml/240 min), not by baclofen. The results suggest that sodium intake caused by gabaergic activation in the LPBN in normohydrated rats is totally dependent on the activation of opioid mechanisms and partially dependent on the activation of α2 adrenergic mechanisms in the LPBN. Department of Biological Sciences DECBI-NUPEB Federal University of Ouro Preto Department of Physiology and Pathology School of Dentistry São Paulo State University UNESP Department of Physiology and Pathology School of Dentistry São Paulo State University UNESP

Made available in DSpace on 2018-12-11T17:35:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Renovascular hypertensive 2-kidney, 1-clip (2K1C) rats have an increased activity of the renin-angiotensin system and an initial transitory increase in daily water and NaCl intake. However, the dipsogenic and natriorexigenic responses to angiotensin II (ANG II) have not been tested yet in 2K1C rats. Therefore, in the present study, we evaluated water and 0.3 M NaCl intake induced by water deprivation (WD)-partial rehydration (PR) or intracerebroventricular (icv) ANG II in 2K1C rats. In addition, the cardiovascular changes to these treatments were also evaluated. Male Holtzman rats received a silver clip around the left renal artery to induce 2K1C renovascular hypertension. In the 5th week, a group of animals received a guide cannula in the lateral ventricle for icv injections. Daily water intake increased from the 3rd week after surgery and remained elevated until the 6th week (last recording week), whereas daily 0.3 M NaCl intake transiently increased from the 2nd to the 5th week after surgery. On the 6th week, in spite of comparable daily 0.3 M NaCl intake between 2K1C and sham rats, WD-PR and icv ANG II induced an increased 0.3 M NaCl intake in 2K1C rats. Water intake induced by WD-PR, not by icv ANG II, also increased in 2K1C rats. The increase in arterial pressure to WD-PR or icv ANG II was similar in sham and 2K1C rats. Therefore, these results suggest that 2K1C rats are more responsive to the natriorexigenic effects of ANG II, whereas other responses to ANG II are not modified. Department of Physiology and Pathology School of Dentistry São Paulo State University UNESP Department of Clinical Analysis School of Pharmacy São Paulo State University UNESP Department of Physiology and Pathology School of Dentistry São Paulo State University UNESP Department of Clinical Analysis School of Pharmacy São Paulo State University UNESP FAPESP: 2011/50770-1 FAPESP: 2015/23467-7

Made available in DSpace on 2018-11-26T17:33:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-04-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) NIH BACKGROUND Macrophage migration inhibitory factor (MIF) is an intracellular inhibitory regulator of the actions of angiotensin II in the central nervous system. Renovascular hypertensive 2-kidney, 1-clip (2K1C) rats have an increased activity of the renin-angiotensin system and a decrease in baroreflex function compared to normotensive (NT) rats. In the present study, we tested the effects of MIF overexpression within the nucleus of the solitary tract (NTS), a key brainstem region for cardiovascular regulation, on the development of hypertension, on baroreflex function, and on water and food intake in 2K1C rats. METHODS Holtzman NT rats received a silver clip around the left renal artery to induce 2K1C hypertension. Three weeks later, rats were microinjected in the NTS with AAV2-CBA-MIF, to increase the expression of MIF, or with the control vector AAV2-CBA-enhanced green fluorescent protein. Mean arterial pressure (MAP) and heart rate were recorded by telemetry. Baroreflex function was tested, and water and food intake were also measured. RESULTS Increasing MIF expression in the NTS of 2K1C rats attenuated the development of hypertension, reversed the impairment of baroreflex function, and reduced the increase in water intake. In contrast to 2K1C rats, similar increases in MIF expression in the NTS of NT rats produced no changes in baseline MAP, baroreflex function, or water intake. CONCLUSIONS These results indicate that an increased expression of MIF within the NTS attenuates the development of hypertension and restores the baroreflex function in 2K1C rats. Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil Univ Sao Paulo, Ribeirao Preto Med Sch, Dept Physiol, Ribeirao Preto, SP, Brazil Southern Med Univ, Sch Biotechnol, Guangzhou, Guangdong, Peoples R China Univ Florida, Coll Med, Dept Physiol & Funct Genom, Gainesville, FL USA Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil CNPq: 473108/2011-9 CNPq: 304918/2011-3 FAPESP: 2011/50770-1 FAPESP: 2015/23467-7 NIH: HL-076803

Made available in DSpace on 2021-06-25T12:29:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) BBSRC MRC DTG Fellowship Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Background/Aims: Furosemide is a loop diuretic widely used in clinical practice for the treatment of oedema and hypertension. The aim of this study was to determine physiological and molecular changes in the hypothalamic-neurohypophysial system as a consequence of furosemide-induced sodium depletion. Methods: Male rats were sodium depleted by acute furosemide injection (10 and 30 mg/kg) followed by access to low sodium diet and distilled water for 24 h. The renal and behavioural consequences were evaluated, while blood and brains were collected to evaluate the neuroendocrine and gene expression responses. Results: Furosemide treatment acutely increases urinary sodium and water excretion. After 24 h, water and food intake were reduced, while plasma angiotensin II and corticosterone were increased. After hypertonic saline presentation, sodium-depleted rats showed higher preference for salt. Interrogation using RNA sequencing revealed the expression of 94 genes significantly altered in the hypothalamic paraventricular nucleus (PVN) of sodium-depleted rats (31 upregulated and 63 downregulated). Out of 9 genes chosen, 5 were validated by quantitative PCR in the PVN (upregulated: Ephx2, Ndnf and Vwf; downregulated: Caprin2 and Opn3). The same genes were also assessed in the supraoptic nucleus (SON, upregulated: Tnnt1, Mis18a, Nr1d1 and Dbp; downregulated: Caprin2 and Opn3). As a result of these plastic transcriptome changes, vasopressin expression was decreased in PVN and SON, whilst vasopressin and oxytocin levels were reduced in plasma. Conclusions: We thus have identified novel genes that might regulate vasopressin gene expression in the hypothalamus controlling the magnocellular neurons secretory response to body sodium depletion and consequently hypotonic stress. Univ Fed Rural Rio de Janeiro, Dept Physiol Sci, Seropedica, Brazil Univ Bristol Sch Med, Mol Neuroendocrinol Res Grp, Translat Hlth Sci, Bristol, Avon, England Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, UNESP, Araraquara, SP, Brazil Queens Univ, Translat Inst Med, Dept Med, Queens Cardiopulm Unit, Kingston, ON, Canada Univ Sao Paulo, Ribeirao Preto Med Sch, Dept Physiol, Ribeirao Preto, Brazil Univ Fed Sao Paulo, Dept Biophys, Lab Neuroendocrinol, Escola Paulista Med, Rua Botucatu 862,Edificio Ciencias Biomed,7 Andar, BR-04023062 Sao Paulo, SP, Brazil Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, UNESP, Araraquara, SP, Brazil FAPESP: 2011/507701 FAPESP: 2013/23057-8 FAPESP: 2019/08621-0 FAPESP: 2013/09799-1 FAPESP: 2014/15218-4 FAPERJ: E26/110.045/2014 FAPERJ: E26/202.981/2015 BBSRC: BB/J005452/1 BBSRC: BB/J015415/1 CAPES: 001 CNPq: 400503/2014-0 : MR/N022807/1

Made available in DSpace on 2019-10-06T17:15:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-05 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Obesity activates the renin-angiotensin and sympathetic systems facilitating hypertension and changes in the hydroelectrolytic balance. In the present study, in rats fed with high-fat diet (HFD), we investigated daily water intake and urinary excretion, prandial consumption of water and the changes in blood pressure and water intake to intracerebroventricular (icv) angiotensin II (ANG II). Male Holtzman rats (290–320 g) were fed with standard diet (SD, 11% calories from fat) or HFD (45% calories from fat) for 6 weeks. Part of the animals received a stainless steel cannula in the lateral ventricle (LV) at the 6th week after the beginning of the diets and the experiments were performed at the 7th week. The pressor effect, but not the dipsogenic response to acute icv injection of ANG II, was potentiated in the HFD rats. Daily water intake and urinary volume were reduced in rats fed with HFD with no significant changes in sodium excretion. Prandial water consumption was also reduced in rats ingesting HFD, an effect almost totally reverted blocking salivation with atropine. These results show a potentiation of the pressor response to icv ANG II in HFD-fed rats, without changing icv ANG II-induced water intake. In addition, prandial and daily water intake and urinary volume were reduced in HFD-fed rats, without changing sodium excretion. Salivation in rats ingesting HFD may play a role in the reduced prandial and daily water intake. Department of Physiology and Pathology School of Dentistry UNESP - São Paulo State University Department of Physiology and Pathology School of Dentistry UNESP - São Paulo State University FAPESP: 2015/234677 FAPESP: 2017/10762-6 CNPq: 308099/2017-6 CNPq: 425586/2016-2

Made available in DSpace on 2019-10-06T16:55:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-16 China Academy of Traditional Chinese Medicine Karunya University Cholinergic activation of the medial septal area (MSA) with carbachol produces thirst, natriuresis and antidiuresis. Hydrogen peroxide (H 2 O 2 ) injected into the medial septal area (MSA) impairs behavioral and renal responses induced by carbachol at the same site, suggesting the exogenous H 2 O 2 may modulate the responses to cholinergic activation in the MSA. In the present study, we investigated if the accumulation of endogenous H 2 O 2 in the MSA after the injection of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ) also affects cholinergic responses. In addition, the effects of the combination of ATZ with a non-effective dose of H 2 O 2 in the MSA were also tested. Male Holtzman rats (280–320 g) with stainless steel cannulas implanted in the MSA were used. The treatment with ATZ (10 nmol) into the MSA partially reverted the antidiuretic effect of carbachol (10.5 ± 0.7, vs. saline + carbachol: 7.3 ± 0.6 ml/120 min), without changing carbachol-induced water intake (9.5 ± 1.9, vs. saline + carbachol: 10.7 ± 1.6 ml/60 min). The combination of a low dose of ATZ (2.5 nmol) with an ineffective dose of H 2 O 2 (0.5 μmol) into the MSA reduced carbachol-induced thirst (7.5 ± 2.0, vs. saline + carbachol: 14.9 ± 1.2 ml/15 min) and reverted the antidiuresis (8.1 ± 1.1, vs. saline + carbachol: 5.3 ± 0.9 ml/120 min). Sodium and potassium excretion were not modified regardless the treatment. Although exogenous H 2 O 2 injected in the MSA may affect most of the responses to cholinergic activation of the MSA, the antidiuresis is the response clearly modulated by endogenous H 2 O 2 . Department of Physiology and Pathology School of Dentistry UNESP – São Paulo State University Department of Physiology and Pathology School of Dentistry UNESP – São Paulo State University China Academy of Traditional Chinese Medicine: 2015/234677 Karunya University: 304873/2014-4 Karunya University: 425586/2016-2

The administration of cholinergic agonists like pilocarpine intraperitoneally (i.p.) or carbachol intracerebroventricularly (i.c.v.) induces water, but non significant hypertonic NaCl intake. These treatments also produce pressor responses, which may inhibit sodium intake. Noradrenaline (NOR) acting on α 2 -adrenoceptors in the lateral parabrachial nucleus (LPBN) deactivates inhibitory mechanisms increasing fluid depletion-induced sodium intake. In the present study, we investigated: (1) water and 1.8% NaCl intake in rats treated with pilocarpine i.p. or carbachol i.c.v. combined with NOR into the LPBN; (2) if inhibitory signals from cardiovascular receptors are blocked by NOR in the LPBN. Male Holtzman rats with stainless steel guide-cannulas implanted in the lateral ventricle and bilaterally in the LPBN were used. Bilateral injections of NOR (80 nmol/0.2 μl) into the LPBN decreased water intake (0.8 ± 0.3, vs. saline (SAL): 2.9 ± 0.3 ml/180 min) induced by pilocarpine (1 mg/kg of body weight) i.p., without changing 1.8% NaCl intake (0.8 ± 2.4, vs. SAL: 0.5 ± 0.3 ml/180 min). Prazosin (1 mg/kg of body weight) i.p. blocked pressor responses and increased water and 1.8% NaCl intake (6.3 ± 1.7 and 14.7 ± 3.5 ml/180 min, respectively) in rats treated with pilocarpine combined with NOR into the LPBN. Prazosin i.p. also increased 1.8% NaCl intake in rats treated with carbachol i.c.v combined with NOR into the LPBN. The results suggest that different signals inhibit sodium intake in rats treated with cholinergic agonists, among them those produced by increases of arterial pressure that are not efficiently deactivated by NOR acting in the LPBN.

With the global epidemic of obesity, breathing disorders associated with excess body weight have markedly increased. Respiratory dysfunctions caused by obesity were originally attributed to mechanical factors; however, recent studies have suggested a pathophysiological component that involves the central nervous system (CNS) and hormones such as leptin produced by adipocytes as well as other cells. Leptin is suggested to stimulate breathing and leptin deficiency causes an impairment of the chemoreflex, which can be reverted by leptin therapy. This facilitation of the chemoreflex may depend on the action of leptin in the hindbrain areas involved in the respiratory control such as the nucleus of the solitary tract (NTS), a site that receives chemosensory afferents, and the ventral surface of the medulla that includes the retrotrapezoid nucleus (RTN), a central chemosensitive area, and the rostral ventrolateral medulla (RVLM). Although the mechanisms and pathways activated by leptin to facilitate breathing are still not completely clear, evidence suggests that the facilitatory effects of leptin on breathing require the brain melanocortin system, including the POMC–MC4R pathway, a mechanism also activated by leptin to modulate blood pressure. The results of all the studies that have investigated the effect of leptin on breathing suggest that disruption of leptin signalling as caused by obesity-induced reduction of central leptin function (leptin resistance) is a relevant mechanism that may contribute to respiratory dysfunctions associated with obesity.

Leptin, a peptide hormone produced by adipose tissue, acts in brain centers that control critical physiological functions such as metabolism, breathing and cardiovascular regulation. The importance of leptin for respiratory control is evident by the fact that leptin deficient mice exhibit impaired ventilatory responses to carbon dioxide (CO2), which can be corrected by intracerebroventricular leptin replacement therapy. Leptin is also recognized as an important link between obesity and hypertension. Humans and animal models lacking either leptin or functional leptin receptors exhibit many characteristics of the metabolic syndrome, including hyperinsulinemia, insulin resistance, hyperglycemia, dyslipidemia and visceral adiposity, but do not exhibit increased sympathetic nerve activity (SNA) and have normal to lower blood pressure (BP) compared to lean controls. Even though previous studies have extensively focused on the brain sites and intracellular signaling pathways involved in leptin effects on food intake and energy balance, the mechanisms that mediate the actions of leptin on breathing and cardiovascular function are only beginning to be elucidated. This mini-review summarizes recent advances on the effects of leptin on cardiovascular and respiratory control with emphasis on the neural control of respiratory function and autonomic activity.

Cholinergic activation of the medial septal area (MSA) with carbachol produces thirst, natriuresis, antidiuresis and pressor response. In the brain, hydrogen peroxide (H 2 O 2 ) modulates autonomic and behavioral responses. In the present study, we investigated the effects of the combination of carbachol and H 2 O 2 injected into the MSA on water intake, renal excretion, cardiovascular responses and the activity of vasopressinergic and oxytocinergic neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Furthermore, the possible modulation of carbachol responses by H 2 O 2 acting through K + ATP channels was also investigated. Male Holtzman rats (280–320 g) with stainless steel cannulas implanted in the MSA were used. The pre-treatment with H 2 O 2 in the MSA reduced carbachol-induced thirst (7.9 ± 1.0, vs. carbachol: 13.2 ± 2.0 ml/60 min), antidiuresis (9.6 ± 0.5, vs. carbachol: 7.0 ± 0.8 ml/120 min,), natriuresis (385 ± 36, vs. carbachol: 528 ± 46 μEq/120 min) and pressor response (33 ± 5, vs. carbachol: 47 ± 3 mmHg). Combining H 2 O 2 and carbachol into the MSA also reduced the number of vasopressinergic neurons expressing c-Fos in the PVN (46.4 ± 11.2, vs. carbachol: 98.5 ± 5.9 c-Fos/AVP cells) and oxytocinergic neurons expressing c-Fos in the PVN (38.5 ± 16.1, vs. carbachol: 75.1 ± 8.5 c-Fos/OT cells) and in the SON (57.8 ± 10.2, vs. carbachol: 102.7 ± 7.4 c-Fos/OT cells). Glibenclamide (K + ATP channel blocker) into the MSA partially reversed H 2 O 2 inhibitory responses. These results suggest that H 2 O 2 acting through K + ATP channels in the MSA attenuates responses induced by cholinergic activation in the same area.

Made available in DSpace on 2018-12-11T17:33:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-08-30 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Angiotensin II (ANG II) is a typical facilitatory stimulus for sodium appetite. Surprisingly, hyperosmolarity and central cholinergic stimulation, two classical antinatriorexigenic stimuli, also facilitate NaCl intake when they are combined with injections of the α2-adrenoceptor/imidazoline agonist moxonidine into the lateral parabrachial nucleus (LPBN). In the present study, we tested the relative importance of central angiotensinergic and cholinergic mechanisms for the control of water and NaCl intake by combining different dipsogenic or natriorexigenic stimuli with moxonidine injection into the LPBN. Adult male Holtzman rats (n = 9–10/group) with stainless steel cannulas implanted in the lateral ventricle and LPBN were used. Bilateral injections of moxonidine (0.5 nmol) into the LPBN increased water and 0.3 M NaCl intake in rats that received furosemide + captopril injected subcutaneously, ANG II (50 ng) or carbachol (cholinergic agonist, 4 nmol) injected intracerebroventricularly (icv) or 2 M NaCl infused intragastrically (2 ml/rat). Losartan (AT1 antagonist, 100 μg) or atropine (muscarinic antagonist, 20 nmol) injected icv abolished the effects on water and 0.3 M NaCl of moxonidine combined to either 2 M NaCl intragastrically or carbachol icv. However, atropine icv did not change 0.3 M NaCl intake produced by direct central action of ANG II like that induced by ANG II icv or furosemide + captopril combined with moxonidine into the LPBN. The results suggest that different stimuli, including hyperosmolarity and central cholinergic stimulation, share central angiotensinergic activation as a common mechanism to facilitate sodium intake, particularly when they are combined with deactivation of the LPBN inhibitory mechanisms. Department of Physiology and Pathology School of Dentistry São Paulo State University UNESP Department of Physiology and Pharmacology School of Medicine Federal University of Ceará Department of Physiology and Pathology School of Dentistry São Paulo State University UNESP

Angiotensin II increases and decreases arterial pressure by acting at angiotensin type 1 and type 2 receptors, respectively. Renovascular hypertensive rats exhibit a high level of activity of the peripheral and central renin–angiotensin system. Therefore, in the present study, we evaluated the effect of increasing the expression of angiotensin type 2 receptors in the solitary–vagal complex (nucleus of the solitary tract/dorsal motor nucleus of the vagus), a key brain stem region for cardiovascular regulation, on the development of renovascular hypertension. Holtzman normotensive rats were implanted with a silver clip around the left renal artery to induce 2-kidney 1-clip renovascular hypertension. Three weeks later, rats were microinjected in the solitary–vagal complex with either an adenoassociated virus to increase the expression of angiotensin type 2 receptors or with a control vector. We observed that increasing angiotensin type 2 receptor expression in the solitary–vagal complex attenuated the development of renovascular hypertension and also reversed the impairment of the baroreflex and the increase in the low-frequency component of systolic blood pressure observed in renovascular hypertensive rats. Furthermore, an observed decrease in mRNA levels of angiotensin-converting enzyme 2 in the solitary–vagal complex of renovascular hypertensive rats was restored to control levels after viral-mediated increases in angiotensin type 2 receptors at this site. Collectively, these data demonstrate specific and beneficial effects of angiotensin type 2 receptors via the brain of hypertensive rats and suggest that central angiotensin type 2 receptors may be a potential target for therapeutics in renovascular hypertension.

UNLABELLED Melanocortin receptors (MC3/4R) mediate most of the metabolic and cardiovascular actions of leptin. AIM Here, we tested if MC4R also contributes to leptin's effects on respiratory function. METHODS After control measurements, male Holtzman rats received daily microinjections of leptin, SHU9119 (MC3/4R antagonist) or SHU9119 combined with leptin infused into the brain lateral ventricle for 7 days. On the 6th day of treatment, tidal volume (VT ), respiratory frequency (fR ) and pulmonary ventilation (VE ) were measured by whole-body plethysmography during normocapnia or hypercapnia (7% CO2 ). Baseline mean arterial pressure (MAP), heart rate (HR) and metabolic rate were also measured. VE , VT and fR were also measured in mice with leptin receptor deletion in the entire central nervous system (LepR/Nestin-cre) or only in proopiomelanocortin neurones (LepR/POMC-cre) and in MC4R knockout (MC4R(-/-) ) and wild-type mice. RESULTS Leptin (5 μg day(-1) ) reduced body weight (~17%) and increased ventilatory response to hypercapnia, whereas SHU9119 (0.6 nmol day(-1) ) increased body weight (~18%) and reduced ventilatory responses compared with control-PBS group (Lep: 2119 ± 90 mL min(-1) kg(-1) and SHU9119: 997 ± 67 mL min(-1) kg(-1) , vs. PBS: 1379 ± 91 mL min(-1) kg(-1) ). MAP increased after leptin treatment (130 ± 2 mmHg) compared to PBS (106 ± 3 mmHg) or SHU9119 alone (109 ± 3 mmHg). SHU9119 prevented the effects of leptin on body weight, MAP (102 ± 3 mmHg) and ventilatory response to hypercapnia (1391 ± 137 mL min(-1) kg(-1) ). The ventilatory response to hypercapnia was attenuated in the LepR/Nestin-cre, LepR/POMC-cre and MC4R(-/-) mice. CONCLUSION These results suggest that central MC4R mediate the effects of leptin on respiratory response to hypercapnia.

New Findings What is the central question of this study? Is sympathorespiratory activity affected in a different manner by cholinergic mechanisms in the intermediate (iNTS) and commissural nucleus of the solitary tract (cNTS) and are cholinergic mechanisms involved in baro- and chemoreflexes? What is the main finding and its importance? Acetylcholine (ACh) injected into the iNTS promotes sympatho-inhibition and reduces the phrenic frequency, whereas ACh injected into the cNTS increases phrenic frequency and affects sympathetic–respiratory coupling, without changing the sympathetic activity. These responses are abolished by mecamylamine (nicotinic antagonist) in the NTS. Mecamylamine in the cNTS also reduces peripheral chemoreflex-induced tachypnoea. The contribution of cholinergic mechanisms of the nucleus of the solitary tract (NTS) to cardiorespiratory control is not completely clear. In the present study, we investigated the involvement of the cholinergic mechanisms in the intermediate NTS (iNTS) and commissural NTS (cNTS) on the control of sympathetic (SNA) and phrenic nerve activity (PNA). Decorticated, arterially perfused in situ preparations of male juvenile rats (60–100 g) were used. Acetylcholine (10 mm, 60 nl) injected into the iNTS reduced SNA (−54 ± 4%, versus vehicle −5 ± 3%; P

Bilateral injections of the GABA(A) agonist muscimol into the lateral parabrachial nucleus (LPBN) induce 0.3 M NaCl and water intake in satiated and normovolemic rats, a response reduced by intracerebroventricular (icv) administration of losartan or atropine (angiotensinergic type 1 (AT₁) and cholinergic muscarinic receptor antagonists, respectively). In the present study, we investigated the effects of the injections of losartan or atropine into the subfornical organ (SFO) on 0.3M NaCl and water intake induced by injections of muscimol into the LPBN. In addition, using intracellular calcium measurement, we also tested the sensitivity of SFO-cultured cells to angiotensin II (ANG II) and carbachol (cholinergic agonist). In male Holtzman rats with cannulas implanted bilaterally into the LPBN and into the SFO, injections of losartan (1 μg/0.1 μl) or atropine (2 nmol/0.1 μl) into the SFO almost abolished 0.3M NaCl and water intake induced by muscimol (0.5 nmol/0.2 μl) injected into the LPBN. In about 30% of the cultured cells of the SFO, carbachol and ANG II increased intracellular calcium concentration ([Ca²⁺](i)). Three distinct cell populations were found in the SFO, i.e., cells activated by either ANG II (25%) or carbachol (2.6%) or by both stimuli (2.3%). The results suggest that the activation of angiotensinergic and cholinergic mechanisms in the SFO is important for NaCl and water intake induced by the deactivation of LPBN inhibitory mechanisms with muscimol injections. They also show that there are cells in the SFO activated by both angiotensinergic and cholinergic stimuli, perhaps those involved in the responses to muscimol into the LPBN.

In the present study, we investigated the effects of lesions of A2 neurons of the commissural nucleus of the solitary tract (cNTS) alone or combined with the blockade of angiotensinergic mechanisms on the recovery of arterial pressure (AP) to hemorrhage in conscious rats. Male Holtzman rats (280–320 g) received an injection of anti-dopamine-beta-hydroxylase-saporin (12.6 ng/60 nl; cNTS/A2-lesion, n = 28) or immunoglobulin G (IgG)-saporin (12.6 ng/60 nl, sham, n = 24) into the cNTS and 15–21 days later had a stainless steel cannula implanted in the lateral ventricle. After 6 days, rats were submitted to hemorrhage (four blood withdrawals, 2 ml/300 g of body weight every 10 min). Both cNTS/A2-lesioned and sham rats had similar hypotension to hemorrhage (−62 ± 7 and −73 ± 7 mmHg, respectively), however cNTS/A2-lesioned rats rapidly recovered from hypotension (−5 ± 3 mmHg at 30 min), whereas sham rats did not completely recover until the end of the recording (−20 ± 3 mmHg at 60 min). Losartan (angiotensin type 1 receptor antagonist) injected intracerebroventricularly (100 μg/1 μl) or intravenously (i.v.) (10 mg/kg of body weight) impaired the recovery of AP in cNTS/A2-lesioned rats (−24 ± 6 and −35 ± 7 mmHg at 30 min, respectively). In sham rats, only i.v. losartan affected the recovery of AP (−39 ± 6 mmHg at 60 min). The results suggest that lesion of the A2 neurons in the cNTS facilitates the activation of the angiotensinergic pressor mechanisms in response to hemorrhage.

Injection of l -glutamate (GLU) into the rostral ventrolateral medulla (RVLM) produces sympathetically-mediated pressor responses that depend on the integrity of the tissue surrounding the anteroventral third ventricle (AV3V region). The injection of angiotensin II (ANG II) or the cholinergic agonist carbachol into the RVLM also produces pressor responses. In the present study, we investigated if the lesion of the AV3V region affects the pressor responses to ANG II or carbachol injected into the RVLM in unanesthetized rats. Male Holtzman rats with sham or electrolytic AV3V lesions and a stainless steel cannula implanted into the RVLM were used. The pressor responses to ANG II (200 ng/100 nl) injected into the RVLM were reduced by acute (1 day) (12 ± 3 vs. sham lesions: 26 ± 4 mmHg) or chronic (15 days) AV3V lesions (12 ± 5 vs. sham lesions: 27 ± 4 mmHg), whereas acute or chronic AV3V lesions did not affect the pressor responses to carbachol (1 nmol/100 nl) injected into the RVLM. The present results suggest that the AV3V region modulates the excitability of the RVLM neurons involved with the pressor response produced by the activation of angiotensinergic mechanisms in this area.

Made available in DSpace on 2018-11-26T17:13:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) NIH The aim of this study was to investigate the physiological effects of increased angiotensin II type 2 receptor (AT2R) expression in the solitary-vagal complex (nucleus of the solitary tract/dorsal motor nucleus of the vagus; NTS/DVM) on baroreflex function in non-anaesthetised normotensive (NT) and spontaneously hypertensive rats (SHR). Ten week old NT Holtzman and SHR were microinjected with either an adeno-associated virus expressing AT2R (AAV2-CBA-AT2R) or enhanced green fluorescent protein (control; AAV2-CBA-eGFP) into the NTS/DVM. Baroreflex and telemetry recordings were performed on four experimental groups: 1) NTeGFP, 2) NTAT2R, 3) SHReGFP and 4) SHRAT2R (n = 4-7/group). Following in-vivo experimental procedures, brains were harvested for gene expression analysis. Impaired bradycardia in SHReGFP was restored in SHR rats over-expressing AT2R in the NTS/DMV. mRNA levels of angiotensin converting enzyme decreased and angiotensin converting enzyme 2 increased in the NTS/DMV of SHRAT2R compared to SHReGFP. Increased levels of pro inflammatory cytokine mRNA levels in the SHReGFP group also decreased in the SHRAT2R group. AT2R overexpression did not elicit any significant change in mean arterial pressure (MAP) in all groups from baseline to 4 weeks post viral transfection. Both SHReGFP and SHRAT2R showed a significant elevation in MAP compared to the NTeGFP and NTAT2R groups. Increased AT2R expression within the NTS/DMV of SHR was effective at improving baroreflex function but not MAP. We propose possible mediators involved in improving baroreflex are in the ANG II/ACE2 axis, suggesting a potential beneficial modulatory effect of AT2R overexpression in the NTS/DMV of neurogenic hypertensive rats. (C) 2016 Elsevier Ltd. All rights reserved. Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil Southern Med Univ, Sch Biotechnol, Guangzhou, Guangdong, Peoples R China Univ Florida, Coll Med, Dept Physiol & Funct Genom, Gainesville, FL USA Univ Florida, Coll Med, McKnight Brain Inst, Gainesville, FL USA Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil CNPq: 473108/2011-9 CNPq: 304918/2011-3 FAPESP: 2011/50770-1 FAPESP: 2012/23546-6 FAPESP: 2013/50121-9 CAPES: 2053/2013 NIH: HL-076803

Made available in DSpace on 2018-11-26T17:20:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-03-15 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Canadian Institutes of Health Research Previously we have demonstrated that microinjection of acetylcholine (ACh) into the intermediate nucleus of the solitary tract (iNTS) induced sympatho-inhibition combined with a decrease in the phrenic nerve activity (PNA), whereas in the commissural NTS (cNTS), ACh did not change sympathetic nerve activity (SNA), but increased the PNA. In view of these demonstrated distinctive effects of ACh in different subnuclei of the NTS the current studies were undertaken to examine, using patch clamp techniques, the specific effects of ACh on the excitability of individual neurons in the NTS, as well as the neuropharmacology of these actions. Coronal slices of the brainstem containing either cNTS or iNTS subnuclei were used, and whole cell patch clamp recordings obtained from individual neurons in these two subnuclei. In cNTS, 58% of recorded neurons (n = 12) demonstrated rapid reversible depolarizations in response to ACh (10 mM), effects which were inhibited by the nicotinic antagonist mecamylamine (10 mu M), but unaffected by the muscarinic antagonist atropine (10 mu M). Similarly, bath application of ACh depolarized 76% of iNTS neurons (n = 17), although in this case both atropine and mecamylamine reduced the ACh-induced depolarization. These data demonstrate that ACh depolarizes cNTS neurons through actions on nicotinic receptors, while depolarizing effects in iNTS are apparently mediated by both receptors. (C) 2017 Elsevier B.V. All rights reserved. Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil Queens Univ, Sch Med, Dept Biomed & Mol Sci, Kingston, ON, Canada Sao Paulo State Univ, Sch Dent, Dept Physiol & Pathol, Araraquara, SP, Brazil FAPESP: FAPESP 2011/20040-1 FAPESP: 2010/17218-0 FAPESP: 2009/54888-7 FAPESP: 2012/05844-0 Canadian Institutes of Health Research: MOP12192

Aims The macrophage migration inhibitory factor (MIF) is an intracellular inhibitor of the central nervous system actions of angiotensin II on blood pressure. Considering that angiotensin II actions at the nucleus of the solitary tract are important for the maintenance of hypertension in spontaneously hypertensive rats (SHRs), we tested if increased MIF expression in the nucleus of the solitary tract of SHR alters the baseline high blood pressure in these rats. Methods and results Eight-week-old SHRs or normotensive rats were microinjected with the vector AAV2-CBA-MIF into the nucleus of the solitary tract, resulting in MIF expression predominantly in neurons. Rats also underwent recordings of the mean arterial blood pressure (MAP) and heart rate (via telemetry devices implanted in the abdominal aorta), cardiac- and baroreflex function. Injections of AAV2-CBA-MIF into the nucleus of the solitary tract of SHRs produced significant decreases in the MAP, ranging from 10 to 20 mmHg, compared with age-matched SHRs that had received identical microinjections of the control vector AAV2-CBA-eGFP. This lowered MAP in SHRs was maintained through the end of the experiment at 31 days, and was associated with an improvement in baroreflex function to values observed in normotensive rats. In contrast to SHRs, similar increased MIF expression in the nucleus of the solitary tract of normotensive rats produced no changes in baseline MAP and baroreflex function. Conclusion These results indicate that an increased expression of MIF within the nucleus of the solitary tract neurons of SHRs lowers blood pressure and restores baroreflex function.

We investigated the mechanisms responsible for increased blood pressure and sympathetic nerve activity (SNA) caused by 2-3 days dehydration (DH) both in vivo and in situ preparations. In euhydrated (EH) rats, systemic application of the AT(1) receptor antagonist Losartan and subsequent pre-collicular transection (to remove the hypothalamus) significantly reduced thoracic (t)SNA. In contrast, in DH rats, Losartan, followed by pre-collicular and pontine transections, failed to reduce tSNA, whereas transection at the medulla-spinal cord junction massively reduced tSNA. In DH but not EH rats, selective inhibition of the commissural nucleus tractus solitarii (cNTS) significantly reduced tSNA. Comparable data were obtained in both in situ and in vivo (anaesthetized/conscious) rats and suggest that following chronic dehydration, the control of tSNA transfers from supra-brainstem structures (e.g. hypothalamus) to the medulla oblongata, particularly the cNTS. As microarray analysis revealed up-regulation of AP1 transcription factor JunD in the dehydrated cNTS, we tested the hypothesis that AP1 transcription factor activity is responsible for dehydration-induced functional plasticity. When AP1 activity was blocked in the cNTS using a viral vector expressing a dominant negative FosB, cNTS inactivation was ineffective. However, tSNA was decreased after pre-collicular transection, a response similar to that seen in EH rats. Thus, the dehydration-induced switch in control of tSNA from hypothalamus to cNTS seems to be mediated via activation of AP1 transcription factors in the cNTS. If AP1 activity is blocked in the cNTS during dehydration, sympathetic activity control reverts back to forebrain regions. This unique reciprocating neural structure-switching plasticity between brain centres emphasizes the multiple mechanisms available for the adaptive response to dehydration.

GABA(A) and GABA(B) receptors are present in the lateral parabrachial nucleus (LPBN), a pontine area involved with inhibitory mechanisms related to the control of sodium appetite. Activation of GABA(A) receptors in the LPBN induces strong ingestion of 0.3 M sodium chloride (NaCl) in normonatremic and euhydrated rats. In the present study, we investigated the effects of the GABA(B) receptor agonist baclofen, injected alone or combined with GABA(A) or GABA(B) receptor antagonists into the LPBN on 0.3 M NaCl, water, 0.06 M sucrose and food intake in normonatremic and euhydrated rats. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. In normonatremic and euhydrated rats, bilateral injections of baclofen (0.5 nmol/0.2 μl) into the LPBN induced 0.3 M NaCl (24.0±3.1 vs. saline: 2.0±0.8 ml/240 min) and water intake (10.6±1.4 vs. saline: 3.5±0.7 ml/240 min) in a two-bottle test. Injections of GABA(B) receptor antagonists CGP 35348 (50 nmol/0.2 μl) or 2-hydroxysaclofen (5 nmol/0.2 μl) or GABA(A) receptor antagonist bicuculline (1.6 nmol/0.2 μl) into the LPBN reduced 0.3 M NaCl (14.1±4.7 ml/240 min; 9.97±2.5 ml/210 min; 8.8±5.9 ml/240 min, respectively) and water intake induced by baclofen injected into the LPBN. Baclofen (0.5 nmol/0.2 μl) injected into the LPBN also induced 0.06 M sucrose intake (21.8±5.9 vs. saline: 5.0±2.6 ml/180 min). Urinary volume and sodium excretion had a tendency to decrease after baclofen injection into the LPBN, whereas arterial pressure and food intake were not affected. The results show that baclofen injected into the LPBN, in normonatremic and euhydrated rats, produces a natriorexigenic effect dependent on GABA(A) and GABA(B) receptor activation. The natriorexigenic effect is not secondary to alterations in blood pressure or sodium urinary excretion. In addition, baclofen injected into the LPBN also induces 0.06 M sucrose intake.

Made available in DSpace on 2013-08-12T18:45:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-01 Made available in DSpace on 2013-09-30T18:32:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:46:04Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T13:46:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) British Heart Foundation Royal Society Reactive oxygen species in peripheral cardiovascular tissues are implicated in the pathogenesis of 2 kidney-1 clip hypertension. We recently identified an imbalance between reactive oxygen species generation and oxidant scavenging in the rostral ventrolateral medulla (RVLM) of 2 kidney-1 clip in rats. We tested whether enhanced superoxide signaling in RVLM of 2 kidney-1 clip rats contributes to the chronic hypertension via sympathetic activation in conscious rats. We enhanced superoxide scavenging in RVLM by overexpressing cytoplasmically targeted superoxide dismutase using an adenoviral vector (Ad-CMV-CuZnSOD) in Wistar rats (male, 150 to 180 g) in which the left renal artery was occluded partially 3 weeks earlier. Hypertension was documented using radiotelemetry recording of arterial pressure in conscious rats for 6 weeks. Renovascular hypertension elevated both serine phosphorylation of p47phox subunit of NADPH and superoxide levels in RVLM. The elevated superoxide levels were normalized by expression of CuZnSOD in RVLM. Moreover, the hypertension produced in the 2 kidney-1 clip rats was reversed 1 week after viral-mediated expression of CuZnSOD. This antihypertensive effect was maintained and associated with a decrease in the low-frequency spectra of systolic blood pressure variability, suggesting reduced sympathetic vasomotor tone. The expression of CuZnSOD was localized to RVLM neurons, of which some contained tyrosine hydroxylase. None of the above variables changed in control rats receiving Ad-CMV-eGFP in RVLM. In Goldblatt hypertension, superoxide signaling in the RVLM plays a major role in the generation of sympathetic vasomotor tone and the chronic sustained hypertension in this animal model. (Hypertension. 2010;56:290-296.) Univ Bristol, Sch Med Sci, Dept Physiol & Pharmacol, Bristol Heart Inst, Bristol BS8 1TD, Avon, England Univ Bristol, Henry Wellcome Labs Integrated Neurosci & Endocri, Bristol BS8 1TD, Avon, England Univ Fed São Paulo, Dept Physiol, São Paulo, Brazil Univ Estadual Paulista, São Paulo State Univ, Dept Physiol & Pathol, Sch Dent, Araraquara, SP, Brazil Cornell Univ, Coll Vet Med, Dept Biomed Sci, Ithaca, NY 14853 USA Weill Cornell Med Coll, Dept Cell & Dev Biol, New York, NY USA Univ Estadual Paulista, São Paulo State Univ, Dept Physiol & Pathol, Sch Dent, Araraquara, SP, Brazil

Pressor responses to l -glutamate into the rostroventrolateral medulla (RVLM) are reduced by lesions of the anteroventral third ventricle (AV3V) region, a main site related to central angiotensinergic pressor mechanisms. Therefore, similar to AV3V lesions, in the present study we investigated if the blockade of central angiotensinergic mechanisms with losartan or ZD 7155 might affect pressor responses to l -glutamate into the RVLM. Male Holtzman rats (280–320 g, n = 4–8/group) with cannulas implanted into the RVLM and lateral ventricle (LV) were used. Injections of l -glutamate (5 nmol/100 nl) or angiotensin II (200 ng/100 nl) into the RVLM increased MAP (54 ± 5 and 26 ± 3 mm Hg, respectively). Losartan (100 µg/1 µl) or ZD 7155 (50 µg/1 µl) injected into the LV reduced the pressor responses to l -glutamate into the RVLM (22 ± 5 and 26 ± 7 mm Hg, respectively), without changing the pressor responses to angiotensin II into the RVLM. Losartan (10 µg/100 nl) or ZD 7155 (5 µg/100 nl) into the RVLM reduced the pressor response to l -glutamate (5 ± 3 and 33 ± 4 mm Hg, respectively) or angiotensin II (5 ± 3 and 6 ± 2 mm Hg, respectively) into the RVLM. Previous injection of angiotensin II (50 ng/100 nl) into the RVLM increased the pressor response to l -glutamate into the RVLM (from 44 ± 5 to 68 ± 7 mm Hg). The results suggest that angiotensinergic mechanisms directly in the RVLM and outside the RVLM (probably forebrain) are important for the pressor responses to l -glutamate into the RVLM.

The blockade of serotoninergic receptors with methysergide or the activation of alpha(2)-adrenoceptors with moxonidine into the lateral parabrachial nucleus (LPBN) increases water and 0.3 M NaCl intake in rats treated with furosemide (FURO) combined with captopril (CAP). In the present study we investigated the effects of bilateral injections of noradrenaline (the endogenous neurotransmitter for alpha-adrenoceptors) alone or combined with the alpha(2)-adrenoceptor antagonist RX 821002 into the LPBN or into the rostral portion of the Kölliker-Fuse nucleus that includes also the A7 area (KF/A7 area) on FURO+CAP-induced water and 0.3 M NaCl intake. Male Holtzman rats with bilateral stainless steel guide-cannulas implanted into KF/A7 area or LPBN were used. FURO+CAP-induced 0.3 M NaCl intake strongly increased after bilateral injections of noradrenaline (80 or 160 nmol/0.2 microl) into LPBN (26.5+/-5.9 and 20.7+/-2.0 ml/2 h versus saline: 4.4+/-0.9 ml/2 h) or into the KF/A7 area (31.5+/-6.1 and 25.9+/-4.7 ml/2 h versus saline: 7.2+/-1.6 ml/2 h). Water intake increased with noradrenaline injected in KF/A7 area, however, this treatment reduced 0.06 M sucrose intake, suggesting that the increase of water and NaCl intake is not related to non-specific effect. Bilateral injections of RX 821002 (160 nmol/0.2 microl) into LPBN or KF/A7 area abolished the effects of noradrenaline (160 nmol/0.2 microl) in the same areas on 0.3 M NaCl intake (7.5+/-2.5 and 9.8+/-4.4 ml/2 h, respectively). Moxonidine (0.5 nmol/0.2 microl) injected bilaterally into the KF/A7 area increased 0.3 M NaCl intake (39.5+/-6.3 ml/3 h) and water intake, while methysergide (4 microg/0.2 microl) into the KF/A7 area did not alter 0.3 M NaCl or water intake. The results suggest that alpha(2)-adrenoceptor activation is a common mechanism in the KF/A7 area and LPBN to facilitate sodium intake. However, the serotonergic mechanism is present in LPBN, not in the KF/A7 area.