Interneuronal δ-GABAA receptors regulate binge drinking and are necessary for the behavioral effects of early withdrawal

Abstract

Extensive evidence points to a role for GABAergic signaling in the amygdala in mediating the effects of alcohol, including presynaptic changes in GABA release, suggesting effects on GABAergic neurons. However, the majority of studies focus solely on the effects of alcohol on principal neurons. Here we demonstrate that δ-GABARs, which have been suggested to confer ethanol sensitivity, are expressed at a high density on parvalbumin (PV) interneurons in the basolateral amygdala (BLA). Thus, we hypothesized that δ-GABARs on PV interneurons may represent both an initial pharmacological target for alcohol and a site for plasticity associated with the expression of various behavioral maladaptations during withdrawal from binge drinking. To investigate this, we used a mouse model of voluntary alcohol intake (Drinking-in-the-Dark-Multiple Scheduled Access) to induce escalating heavy binge drinking and anxiety-like behavior in mice. This pattern of intake was associated with increased δ protein expression on parvalbumin positive interneurons in both the BLA and hippocampus. Loss of δ-GABARs specifically in PV interneurons (PV:δ) increased binge drinking behavior, reduced sensitivity to alcohol-induced motor incoordination, enhanced sensitivity to alcohol-induced hyperlocomotion and blocked the expression of withdrawal from binge drinking. This study is the first to demonstrate a role for δGABARs specifically in PV-expressing interneurons in modulating binge alcohol intake and withdrawal-induced anxiety.

Contrasting sex-dependent adaptations to synaptic physiology and membrane properties of prefrontal cortex interneuron subtypes in a mouse model of binge drinking

“…Transgenic mouse lines have been engineered to express fluorescent markers and manipulate protein expression under the control of the PV promotor (Taniguchi et al, 2011), enabling the means to selectively manipulate the physiology of PV-expressing interneurons (PV-INs). Recent studies have leveraged these tools to reveal that GABAA receptor subunit ablation from PV-INs increases binge drinking in male mice, but not female mice, supporting the hypothesis that this interneuron subtype regulates sex differences in top-down control (Melon et al, 2018). In addition to PV-INs, the second class of deep layer PFC interneurons expresses the neuropeptide somatostatin (SST-INs).…”

Contrasting adaptations to synaptic physiology of prefrontal cortex interneuron subtypes in a mouse model of binge drinking

“…86 physiology of PV-expressing interneurons (PV-INs). Recent studies have leveraged these tools 121 to reveal that GABAA receptor subunit ablation from PV-INs increases binge drinking in male 122 mice, but not female mice, supporting the hypothesis that this interneuron subtype regulates sex 123 differences in top-down control (Melon et al, 2018). In addition to PV-INs, the second class of Mice provided with IA ethanol drink more per day than continuous access controls (Hwa et al, 164 2011), and the C57BL/6J strain consumes more ethanol than other strains (Belknap et al, 1993;165 Boyce-Rustay et al, 2008; Rodgers and Mc, 1962).…”

Sex differences in the alcohol-mediated modulation of BLA network states

“…Previous literature has supported the role of δ-GABAARs in mediating the effects of alcohol on tonic inhibition, drinking and withdrawal behaviors (Wallner et al, 2003;Santhakumar et al, 2007;Melón et al, 2018;Darnieder et al, 2019). Therefore, to test the role of this receptor subunit on mediating the ability of alcohol to modulate BLA network states, we repeated the same procedure as described above in male and female Gabrd -/mice.…”

“…Immunohistochemistry was performed as previously reported (Melón et al, 2018) in a separate cohort of mice following the acute or repeated alcohol exposure paradigms. Mice were anesthetized with isoflurane, transcradially perfused with 0.9% saline and 4% paraformaldehyde (PFA), the brains were rapidly excised, fixed in 4% PFA overnight, and subsequently cryoprotected in 10% and 30% sucrose.…”

“…Our lab has also demonstrated that PV interneurons in the BLA express a high density of extrasynaptic δ subunit-containing GABAARs, which are uniquely sensitive to alcohol and play a role in regulating both alcohol consumption and anxiety-like behaviors, including anxiety associated with alcohol withdrawal (Glykys et al, 2007;Melón et al, 2018;Antonoudiou et al, 2021). Tonic inhibition mediated by δ-GABAARs has been shown to control hippocampal oscillations (Mann and Mody, 2010;Pavlov et al, 2014) and loss of the δ subunit in PV interneurons alters gamma oscillations in the CA3 region of the hippocampus Mody, 2013, 2014).…”