Central moxonidine on salivary gland blood flow and cardiovascular responses to pilocarpine

Peripheral treatment with the cholinergic agonist pilocarpine induces intense salivation that is inhibited by central injections of the alpha(2)-adrenergic/imidazoline receptor agonist moxonidine. Salivary gland blood flow controlled by sympathetic and parasympathetic systems may affect salivation. We investigated the changes in mean arterial pressure (MAP) and in the vascular resistance in the submandibular/sublingual gland (SSG) artery, superior mesenteric (SM) artery and low abdominal aorta (hindlimb) in rats treated with intraperitoneal (i.p.) pilocarpine alone or combined with intracerebroventricular (i.c.v.) moxonidine. Male Holtzman rats with stainless steel cannula. implanted into lateral ventricle (LV) and anesthetized with urethane were used. Pilocarpine (4 mumol/kg of body weight) i.p. reduced SSG vascular resistance (-50 +/- 13% vs. vehicle: 5 +/- 3%). Pilocarpine i.p. also increased mesenteric vascular resistance (15 +/- 5% vs. vehicle: 2 +/- 3%) and MAP (16 +/- 3 mmHg, vs. vehicle: 2 +/- 3 mmHg). Moxonidine (20 nmol) i.c.v. increased SSG vascular resistance (88 +/- 12% vs. vehicle: 7 +/- 4%). When injected 15 min following i.c.v. moxonidine, pilocarpine i.p. produced no change on SSG vascular resistance. Pilocarpine-induced pressor responses and increase in mesenteric vascular resistance were not modified by i.c.v. moxonidine. The treatments produced no change in heart rate (HR) and hindlimb vascular resistance. The results show that (1) i.p. pilocarpine increases mesenteric vascular resistance and MAP and reduces salivary gland vascular resistance and (2) central moxonidine increases salivary gland vascular resistance and impairs pilocarpine-induced salivary gland vasodilatation. Therefore, the increase in salivary gland vascular resistance may play a role in the anti-salivatory response to central moxonidine. (C) 2003 Elsevier B.V. All rights reserved.

The bradycardic and hypotensive responses to serotonin are reduced by activation of GABA A receptors in the nucleus tractus solitarius of awake rats

We investigated the effects of bilateral injections of the GABA receptor agonists muscimol (GABA A) and baclofen (GABA B) into the nucleus tractus solitarius (NTS) on the bradycardia and hypotension induced by iv serotonin injections (5-HT, 2 µg/rat) in awake male Holtzman rats. 5-HT was injected in rats with stainless steel cannulas implanted bilaterally in the NTS, before and 5, 15, and 60 min after bilateral injections of muscimol or baclofen into the NTS. The responses to 5-HT were tested before and after the injection of atropine methyl bromide. Muscimol (50 pmol/50 nl, N = 8) into the NTS increased basal mean arterial pressure (MAP) from 115 ± 4 to 144 ± 6 mmHg, did not change basal heart rate (HR) and reduced the bradycardia (-40 ± 14 and -73 ± 26 bpm at 5 and 15 min, respectively, vs -180 ± 20 bpm for the control) and hypotension (-11 ± 4 and -14 ± 4 mmHg, vs -40 ± 9 mmHg for the control) elicited by 5-HT. Baclofen (12.5 pmol/50 nl, N = 7) into the NTS also increased basal MAP, but did not change basal HR, bradycardia or hypotension in response to 5-HT injections. Atropine methyl bromide (1 mg/kg body weight) injected iv reduced the bradycardic and hypotensive responses to 5-HT injections. The stimulation of GABA A receptors in the NTS of awake rats elicits a significant increase in basal MAP and decreases the cardiac Bezold-Jarisch reflex responses to iv 5-HT injections.

FURO/CAP: A protocol for sodium intake sensitization

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Baclofen into the lateral parabrachial nucleus induces hypertonic sodium chloride and sucrose intake in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Role of serotonergic 5-HT1A and oxytocinergic receptors of the lateral septal area in sodium intake regulation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vasopressin and angiotensin receptors of the medial septal area in the control of mean arterial pressure induced by vasopressin

Introduction. Brain arginine(8)-vasopressin (AVP), through the V-1a- and V-2-receptors, is essential for the maintenance of mean arterial pressure (MAP). Central AVP interacts with the components of the renin-angiotensin system, which participate in MAP regulation. This study all to determine the effects of V-1a-, V-2- and V-1a/V-2-AVP selective antagonists and AT(1)- and AT(2)-angiotensin II (Ang II) selective antagonists on the MAP induced by AVP injected into the medial septal area (MSA) of the brain.Materials and methods. Male Holtzman rats with stainless steel cannulae implanted into the MSA were used in experiments. Direct MAP was recorded in Conscious rats.Results. AVP administration into the MSA caused a prompt and potent pressor response in a dose-dependent fashion. Pretreatment with the V-1a- and V-2-antagonists reduced, whereas prior injection of the V-1a/V-2-antagonist induced a decrease in the MAP that remained below the baseline. Both AT(1)- and AT(2)-antagonists elicited a decrease, While simultaneous injections of two antagonists were more effective in decreasing the MAP induced AVP.Conclusion. These results indicate there is a synergism bell the V-1a- and V-2-AVP, and AT(1)- AT, and AT(2)-Ang II receptors in the MSA in the regulation of MAP.

Activation of alpha(2)-adrenoceptors in the lateral hypothalamus reduces pilocarpine-induced salivation in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

On a possible dual role for the lateral septal area 5-HT1A receptor system in the regulation of water intake and urinary excretion

The 5-hydroxytryptamine (5-HT)(1A) receptor system plays a prominent role in a variety of physiological functions and behavior and regulation of this responsiveness of the receptor system has been implicated in the central regulation of water intake and urinary excretion. The lateral septal area (LSA) exhibits a high density of 5-HT1A receptors, as well as a subpopulation of oxytocin (OT) receptors. Here we report the effects of pMPPF (a selective 5-HT1A antagonist), d(CH2)(5)[Tyr(Me)(2)Thr(4), Orn(5), Tyr(NH2)(9)]-vasotocin (an OT antagonist), and that 5-HT1A receptor system is regulated as a consequence of activation of the Na+ channel by veratridine. Cannulae were implanted into the LSA of rats to enable the introduction of the drugs. Injections of 8-OH-DPAT (a 5-HT1A agonist) blocked water intake and increased urinary excretion, while pMPPF or the OT antagonist injected bilaterally before 8-OH-DPAT blocked its inhibitory effect on water intake and its diuretic effect. In contrast, increases in extracellular sodium levels induced by the sodium channel modulator, veratridine, enhanced 5-HT1A responsiveness for water intake and reduced the diuretic effects induced by 8-OH-DPAT. These trials demonstrated that the responsiveness of the 5-HT1A receptor system in the LSA can be enhanced or depressed as a consequence of an induced rise in extracellular sodium. (C) 2010 Elsevier B.V. All rights reserved.

The Effect of Supra- and Subphysiologic Testosterone Levels on Ligature-Induced Bone Loss in Rats - A Radiographic and Histologic Pilot Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Activation of the serotonergic 5-HT1A receptor in the paraventricular nucleus of the hypothalamus inhibits water intake and increases urinary excretion in water-deprived rats

The paraventricular nucleus (PVN) may be considered as a dynamic mosaic of chemically-specified subgroups of neurons. 5-HT1A is one of the prime receptors identified and there is expressed throughout all magnocellular regions of the PVN. Several reports have demonstrated that a subpopulation of the magnocellular neurons expressing 5-HT1A receptors are oxytocin (OT) neurons and activation of 5-HT1A receptors in the PVN increases the plasma OT. Increasing evidence shows that OT inhibits water intake and increases urinary excretion in rats. The aim of this study was to investigate the role of serotonergic 5-HT1A receptors in the lateral-medial posterior magnocellular region of the PVN in the water intake and diuresis induced by 24 h of water deprivation. Cannulae were implanted in the PVN of rats. 5-HT injections in the PVN reduced water intake and increased urinary excretion. 8-OH-DPAT (a 5-HT1A agonist) injections blocked the water intake and increased urinary output in all the periods of the observation. pMPPF (a 5-HT1A antagonist) injected bilaterally before the 8-OH-DPAT blocked its inhibitory effect on water intake and its diuretic effect. We suggest that antidipsogenic and diuretic responses seem to be mediated via 5-HT1A receptors of the lateral-medial posterior magnocellular region of the PVN in water-deprived rats. (C) 2008 Elsevier B.V. All rights reserved.

Adrenergic mechanisms of the Kölliker-Fuse/A7 area on the control of water and sodium intake

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Importance of angiotensinergic mechanisms for the pressor response to L-glutamate into the rostral ventrolateral medulla

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lesions in the central amygdala impair sodium intake induced by the blockade of the lateral parabrachial nucleus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lateral parabrachial nucleus and central amygdala in the control of sodium intake

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)