Exercise augments but sinoaortic denervation blocks noradrenergic signaling to PVN in trained normotensive rats (686.5)

Exercise training (T) increases ascending NORergic signaling from NTS to PVN, improves baroreflex sensitivity (BrS) and reduces basal heart rate (HR). We evaluate the effects of sinoaortic denervation (SAD) and T on cardiovascular parameters and expression of PVN oxytocinergic (OTergic) and vasopressinergic (VPergic) neurons. SAD and SHAM rats were submitted to low-intensity T or kept sedentary (S) for 3 month. After hemodynamic measurements, rats were euthanized; perfused brains were post-fixed and cryoprotected. Sequential PVN slices (30 μm) were processed for OT, VP and dopamine β-hydroxylase (DBH) immunoreactivity (ir); images were acquired and analyzed by Image J. In SHAM rats T reduced basal HR, increased BrS (328±8 b/min, 2.4±0.2 b/min/mmHg, -13% and +25% vs S controls), augmented the density of DBH terminals and OTir in ventromedial PVN and reduced VPir in the magnocelular PVN, without changing DBH signaling to this area. SAD markedly reduced basal OTir and VPir in both PVN areas and blocked funct...