Chronic intermittent ethanol and acute stress similarly modulate BNST CRF neuron activity via noradrenergic signaling

Abstract

Relapse is a critical barrier to effective long-term treatment of alcoholism, and stress is often cited as a key trigger to relapse. Numerous studies suggest that stress-induced reinstatement to drug seeking behaviors is mediated by norepinephrine (NE) and corticotropin releasing factor (CRF) signaling interactions in the bed nucleus of the stria terminalis (BNST), a brain region critical to many behavioral and physiologic responses to stressors. Here we sought to directly examine the effects of NE on BNST CRF neuron activity and determine if these effects may be modulated by chronic intermittent EtOH (CIE) exposure or a single restraint stress. Utilizing whole-cell patch clamp electrophysiological techniques in CRF-tomato reporter mice, we found that NE depolarized BNST CRF neurons in naive mice in a {beta}-adrenergic receptor (AR) dependent mechanism. CRF neurons from CIE or stress-exposed mice had significantly elevated basal resting membrane potential compared to naive mice. Furthermore, CIE and stress individually disrupted the ability of NE to depolarize CRF neurons, suggesting that both stress and CIE utilize {beta}-AR signaling to modulate BNST CRF neurons. Neither stress nor CIE altered the ability of exogenous NE to inhibit evoked glutamatergic transmission onto BNST CRF neurons, a mechanism previously shown to be -AR dependent. Altogether these findings suggest that stress and CIE interact with {beta}-AR signaling to modulate BNST CRF neuron activity, potentially disrupting the /{beta}-AR balance of BNST CRF neuronal excitability. Restoration of /{beta}-AR balance may lead to novel therapies for the alleviation of many stress-related disorders.