Solitary Nitric Oxide Signaling Mediates Mild Stress-Induced Anxiety and Norepinephrine Release in the Bed Nucleus of the Stria Terminalis during Protracted Ethanol Withdrawal

Abstract

Ethanol withdrawal (EtOHW) alters the pattern of neurohormonal and behavioral response toward internal and external stimuli, which mediates relapse to alcohol use even after a long period of abstinence. Increased noradrenergic signaling from the nucleus tractus solitarius (NTS) to the bed nucleus of the stria terminalis (BNST) during EtOHW underlies withdrawal-induced anxiety, while nitric oxide synthase (NOS) inhibitors injected into the periaqueductal area attenuate EtOHW-induced anxiety. Therefore, this study investigated the involvement of NOS within the NTS in anxiety and increased norepinephrine (NE) release in the BNST during protracted EtOHW in rats exposed to a mild stress. Rats were intraperitoneally administered 3 g/kg/day EtOH for 21 days followed by 28 days of withdrawal, and on the 28th day of withdrawal, the rats were subjected to restraint stress for 7 minutes. The elevated plus maze test was employed to evaluate anxiety-like behavior in rats, and in vivo microdialysis was used to measure the extracellular NE level in the BNST. In elevated plus maze tests, EtOHW rats but not EtOH-naive rats exhibited anxiety-like behavior when challenged with 7-minute mild restraint stress, which was, respectively, mitigated by prior intra-NTS infusion of the nitric oxide scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), nonselective NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME), or selective neuronal NOS (nNOS) inhibitor 7-nitroindazole (7-NI). Each of these agents also decreased the plasma corticosterone levels in EtOHW rats. In in vivo microdialysis, prior intra-NTS infusion of carboxy-PTIO, L-NAME, or 7-NI attenuated the mild stress-induced NE release in the BNST of EtOHW rats. Additionally, EtOHW rats showed increased solitary nNOS gene and protein expression. Moreover, the anxiolytic effect of intra-NTS administration of 7-NI was abolished by subsequent intra-NTS administration of sodium nitroprusside. These results suggest that elevation of solitary nitric oxide signaling derived from nNOS mediates stress-precipitated anxiety and norepinephrine release in the BNST during protracted EtOHW.

Role of noradrenergic transmission within the ventral bed nucleus of the stria terminalis in nicotine withdrawal‐induced aversive behavior

“… 11 Zhao et al recently reported that acute mild‐restraint stress increased intra‐vBNST noradrenaline levels in ethanol withdrawal rats but not in ethanol‐naive control rats. 12 They also found that ethanol withdrawal rats, but not controls, exhibited anxiety‐like behavior in the elevated plus‐maze test after exposure to acute mild‐restraint stress, suggesting the possible involvement of intra‐vBNST noradrenergic transmission in stress‐induced anxiety in ethanol withdrawal rats. These findings, including those obtained in the present study, suggest that noradrenergic transmission in the vBNST plays a critical role in the induction of negative emotions such as aversion and anxiety by withdrawal from various drugs of abuse.…”

“…Delfs et al reported that microinjection of β‐antagonists or an α 2 ‐agonist into the BNST markedly attenuated opiate withdrawal‐induced CPA in rats 11 . Zhao et al recently reported that acute mild‐restraint stress increased intra‐vBNST noradrenaline levels in ethanol withdrawal rats but not in ethanol‐naive control rats 12 . They also found that ethanol withdrawal rats, but not controls, exhibited anxiety‐like behavior in the elevated plus‐maze test after exposure to acute mild‐restraint stress, suggesting the possible involvement of intra‐vBNST noradrenergic transmission in stress‐induced anxiety in ethanol withdrawal rats.…”

Chronic intermittent ethanol exposure disrupts stress-related tripartite communication to impact affect-related behavioral selection in male rats

“…Indeed, many groups have highlighted a hyperadrenergic state in withdrawal (reviewed in Vazey et al, 2018 ). Both NE content ( Varodayan et al, 2022 ) and basal release ( Zhao et al, 2021 ) in CNS regions of rodents during protracted withdrawal from CIE are unchanged, further suggesting that the observed effects of NE application are due to altered astrocytic AR signaling. NE + Praz further suppressed the amplified peak and anti-peak of CIE astrocytes, highlighting a potential mechanism by which α1AR can be therapeutically targeted in CIE ( Li et al, 2020 ).…”