Alpha adrenergic receptor signaling in the hypothalamic paraventricular nucleus is diminished by the chronic intermittent hypoxia model of sleep apnea.

Alpha adrenergic receptor signaling in the hypothalamic paraventricular nucleus is diminished by the chronic intermittent hypoxia model of sleep apnea. Exp Neurol. 2020 Oct 23;335:113517 Authors: Domingos-Souza G, Martinez D, Sinkler S, Heesch CM, Kline DD Abstract Chronic intermittent hypoxia (CIH) is a model for obstructive sleep apnea. The paraventricular nucleus (PVN) of the hypothalamus has been suggested to contribute to CIH-induced exaggerated cardiorespiratory reflexes, sympathoexcitation and hypertension. This may occur, in part, via activation of the dense catecholaminergic projections to the PVN that originate in the brainstem. However, the contribution of norepinephrine (NE) and activation of its alpha-adrenergic receptors (α-ARs) in the PVN after CIH exposure is unknown. We hypothesized CIH would increase the contribution of catecholaminergic input. To test this notion, we determined the expression of α-AR subtypes, catecholamine terminal density, and synaptic properties of PVN parvocellular neurons in response to α-AR activation in male Sprague-Dawley normoxic (Norm) and CIH exposed rats. CIH decreased mRNA for α1d and α2b AR. Dopamine-β-hydroxylase (DβH) terminals in the PVN were similar between groups. NE and the α1-AR agonist phenylephrine (PE) increased sEPSC frequency after Norm but not CIH. Block of α1-ARs with prazosin alone did not alter sEPSCs after either Norm or CIH but did prevent agonist augmentati...
Source: Experimental Neurology - Category: Neurology Authors: Tags: Exp Neurol Source Type: research