Sexually dimorphic role for insular perineuronal nets in aversion-resistant alcohol consumption

Abstract

Compulsive alcohol drinking is a key symptom of alcohol use disorder (AUD) that is particularly resistant to treatment. An understanding of the biological factors that underly compulsive drinking will allow for the development of new therapeutic targets for AUD. One animal model of compulsive alcohol drinking involves the addition of bitter-tasting quinine to an ethanol solution and measuring the willingness of the animal to consume ethanol despite the aversive taste. Previous studies have demonstrated that this type of aversion-resistant drinking is modulated in the insular cortex of male mice by specialized condensed extracellular matrix known as perineuronal nets (PNNs), which form a lattice-like structure around parvalbumin-expressing neurons in the cortex. Several laboratories have shown that female mice exhibit higher levels of aversion-resistant ethanol intake, but the role of PNNs in females in this behavior has not been examined. Here we compared PNNs in the insula of male and female mice and determined if disrupting PNNs in female mice would alter aversion-resistant ethanol intake. PNNs were visualized in the insula by fluorescent labeling with Wisteria floribunda agglutinin (WFA) and disrupted in the insula by microinjecting chondroitinase ABC, an enzyme that digests the chondroitin sulfate glycosaminoglycan component of PNNs. Mice were tested for aversion-resistant ethanol consumption by the addition of sequentially increasing concentrations of quinine to the ethanol in a two-bottle choice drinking in the dark procedure. PNN staining intensity was higher in the insula of female compared to male mice, suggesting that PNNs in females might contribute to elevated aversion-resistant drinking. However, disruption of PNNs had limited effect on aversion-resistant drinking in females. In addition, activation of the insula during aversion-resistant drinking, as measured by c-fos immunohistochemistry, was lower in female mice than in males. Taken together, these results suggest that neural mechanisms underlying aversion-resistant ethanol consumption differ in males and females.

Estradiol mediates sex differences in aversion-resistant alcohol intake

“…For example, our lab has found that females continue to consume quinine-adulterated alcohol at concentrations of this tastant where males significantly reduce their consumption (Fulenwider et al, 2019;. This agrees with other studies that have observed increased aversion-resistant alcohol intake in females (Sneddon et al, 2020;Martins de Carvalho et al, 2023), but it should be noted that some studies have not detected a sex difference in this measure (Sneddon et al, 2019;Bauer et al, 2021;Katner et al, 2022). These disparate findings may be due to differences in drinking model and duration of alcohol access (see Arnold and Schank, 2023 for review).…”

“…This group also observed that degradation of perineuronal nets, which increases glutamatergic output from the insular cortex, reduces quinine-alcohol consumption (Chen and Lasek, 2019). In line with these findings, Martins de Carvalho et al detected lower Fos activation in females compared to males in the anterior insula after quinine-adulterated alcohol drinking (Martins de Carvalho et al, 2023). Most of the findings above agree with the results of our recent experiments, in which we observed increased Fos activation in the posterior insular cortex of male mice, which more readily suppress their alcohol intake when adulterated with quinine .…”

Divergent gene expression patterns in alcohol and opioid use disorders lead to consistent alterations in functional networks within the Dorsolateral Prefrontal Cortex

“…All shared genes within this GO domain exhibited changes in the same direction in the AUD and OUD groups. Research suggests that ECM remodeling directly influences neuroadaptations associated with chronic opioid exposure, while perineuronal nets, specialized ECM structures surrounding inhibitory neurons, may contribute to compulsive drinking behaviors in AUD through the mediation of reward memories [34]. These findings underscore the intricate relationship between ECM remodeling and addiction, illustrating the adaptable interplay between these systems in response to addictive drugs.…”

Retrieval of an ethanol-conditioned taste aversion promotes GABAergic plasticity in the insular cortex

“…A 2g/kg dose of ethanol did not produce any observable differences in strength of ethanol-CTA between males and females in the present experiments; however, some evidence exists to suggest that females may be less sensitive to the aversive effects of ethanol relative to males across multiple behavioral paradigms, including ethanol-CTA (Sherrill et al, 2011;Morales et al, 2014) . A recent report noted that disruption of IC PNNs significantly increased sensitivity to quinine-adulterated ethanol in male mice, but not in female mice unless a very high concentration of quinine was added (Martins de Carvalho et al, 2023). Thus, the mechanisms driving both aversion-resistant drinking and strength of ethanol's aversive effects may differ between males and females; our data lend support to the possibility that this difference may be driven in part by sex-dependent roles of IC PV interneurons in encoding ethanol's aversive effects.…”