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Effects of sinoaortic denervation in the expression and activity of bulbar vasopressinergic and oxytocinergic projections on autonomic control in sedentary and trained normotensive and hypertensive rats

Abstract

We have shown previously that low intensity exercise training besides the well known peripheral effects (cardiac and vascular remodeling, with arterial pressure fall [AP] in hypertensive rats), also modified the autonomic control of the heart, causing resting bradycardia and smaller exercise tachycardia in both normotensive and hypertensive rats. Recent data from our laboratory also showed that training caused extensive plastic and functional changes within different components of suprabulbar modulatory pathways controlling autonomic outflow to heart and vessels: 1) it increases ascending NORergic signaling from the nucleus of the solitary tract (NTS) to hypothalamic preautonomic neurons (PVN); 2) it remodels PVN preautonomic neurons by augmenting their dendritic trees; 3) it increases the intrinsic excitability of PVN preautonomic neurons projecting to the NTS, without changing the activity of magnocellular neurons; 4) it augments oxytocin (OT) expression within the PVN and OT immunoreactivity in the dorsal brain stem (DBS, involving the NTS and DMV areas) without changing the expression its receptors, thus facilitating both the vagal outflow and the reduction of resting HR and exercise tachycardia; 5) it increase the sensitivity of NTS vasopressin (VP) receptors to the endogenous agonist, causing resetting of the baroreflex and the occlusion of reflex bradycardia during exercise-induced AP increases. These training-induced adjustments may facilitate the reduction of sympathetic activity in hypertensive animals, but there is no clue on the mechanisms involved as well as nothing is known on the effects of training on the expression/activity of autonomic pathways to the ventral brain stem (VBS, the origin of premotor sympathetic neurons). We also do not know what is(are) the driving mechanism(s) that elicit autonomic adjustments to training. In this project we sought to investigate the role played by arterial baroreceptors (afferent signaling) in the mediation training-induced autonomic responses. Our objectives are as follow: 1) to quantify plastic changes induced by training on VPergic and OTergic projections from PVN to DBS and VBS of normotensive and hypertensive rats submitted to sinoaortic denervation (SAD) or SHAM surgery; 2) to compare in these groups of rats the autonomic responses induced by training; 3) to associate plastic and functional responses in sedentary and trained normotensive and hypertensive rats in the presence and absence of SAD. (AU)

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Scientific publications (4)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MASSON, GUSTAVO S.; COSTA, TASSIA S. R.; YSHII, LIDIA; FERNANDES, DENISE C.; SILVA SOARES, PEDRO PAULO; LAURINDO, FRANCISCO R.; SCAVONE, CRISTOFORO; MICHELINI, LISETE C.. Time-Dependent Effects of Training on Cardiovascular Control in Spontaneously Hypertensive Rats: Role for Brain Oxidative Stress and Inflammation and Baroreflex Sensitivity. PLoS One, v. 9, n. 5, . (09/54299-1)
CAVALLERI, MARINA T.; BURGI, KATIA; CRUZ, JOSIANE C.; JORDAO, MARIA T.; CERONI, ALEXANDRE; MICHELINI, LISETE C.. Afferent signaling drives oxytocinergic preautonomic neurons and mediates training-induced plasticity. AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY, v. 301, n. 4, p. R958-R966, . (09/54299-1)
CHAAR, LAIALI JURDI; ALVES, TATIANA PEREIRA; BATISTA JUNIOR, ALVARO MARTINS; MICHELINI, LISETE COMPAGNO. Early Training-Induced Reduction of Angiotensinogen in Autonomic Areas-The Main Effect of Exercise on Brain Renin-Angiotensin System in Hypertensive Rats. PLoS One, v. 10, n. 9, . (09/54299-1, 11/51410-9, 09/03708-9)
CRUZ, JOSIANE C.; CAVALLERI, MARINA T.; CERONI, ALEXANDRE; MICHELINI, LISETE C.. Peripheral chemoreceptors mediate training-induced plasticity in paraventricular nucleus pre-autonomic oxytocinergic neurons. Experimental Physiology, v. 98, n. 2, p. 386-396, . (09/54299-1)

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