From binge eating to binge drinking: A new and robust paradigm for assessing binge ethanol self‐administration in male rats

Abstract

Animal models of alcohol (ethanol) self-administration are crucial to dissect the neurobiological mechanisms underlying alcohol dependence, yet only a few of these induce pharmacologically relevant levels of alcohol consumption and rarely the alcohol self-administration co-occurs with other addictive behaviours. The present study aims to validate a novel model of voluntary ethanol consumption in male Wistar rats, in which ethanol access follows a binge eating experience. Over 10 sessions, Wistar rats were exposed to binge or control eating (i.e., the ingestion of 11.66 and 0.97 kcal/3 min, respectively, derived from a highly palatable food), immediately followed by two-bottle choice intake tests (2%, 6%, 10% or 14% w/w ethanol vs. water). Rats exposed to binge eating drank significantly more 6% or 10% (w/w) ethanol than control peers, reaching up to 6.3 g EtOH /kg. Rats stimulated with 2%, 6%, 10% or 14% ethanol after binge eating, but not those given those ethanol concentrations after control eating, exhibited significant within-group increases in ethanol drinking. This ethanol consumption was not altered by quinine adulteration (up to 0.1 g/L), and it was blocked by naltrexone (10 mg/kg), administered immediately before binge eating. Blood ethanol levels significantly correlated with ethanol consumption; and the more ethanol consumed, the greater the distance travelled in

Binge eating promotes ethanol self-administration in female rats with a history of intermittent ethanol exposure at adolescence

“…This engagement in BE was associated with heightened ethanol self-administration, as measured in a limited access procedure immediately after the ingestion of the food. These results (Ruiz-Leyva et al, 2022) pinpoint to interactions between BE and ethanol drinking, that can favor the development of ethanol use problems. These findings are consistent with studies indicating substantial comorbidity between eating disorders and substance use disorders (Root et al, 2010), and with suggestions that common neurobiological mechanisms underly both phenomena (Lindgren et al, 2018).…”

“…We adapted a procedure (Ruiz-Leyva et al, 2022), developed to induce the ingestion of a relatively high amount of carbohydrate-based food in a short timeframe. Specifically, the rats were given 1 (controls rats) or 12 highly palatable sugary pills to eat in 3 minutes (1.16 or 13.86 kcal, respectively), daily for 10 days, beginning at PD80.…”

“…We have reported (Ruiz-Leyva et al, 2022) that the rapid ingestion of hyperpalatable food heightens, in male Wistar rats, binge ethanol drinking. In this preparation the rats are daily and briefly (3 min) exposed to a large quantity of sugary pellets.…”

“…IEA can also increase subsequent ethanol consumption (Fabio et al, 2014), albeit the results concerning this outcome are mixed, with several studies failing to report alterations in ethanol intake at adulthood (Towner and Varlinskaya, 2020). Also uncertain is whether the promoting effects of BE upon ethanol drinking, as shown in Ruiz-Leyva et al (2022), are found in females and are modulated by IEA at adolescence. The present study filled this void by exposing female Wistar rats to an IEA procedure at adolescence; and then assessed ethanol selfadministration via an adapted version of the "binge eating to binge drinking" model (Ruiz-Leyva et al, 2022).…”

“…Also uncertain is whether the promoting effects of BE upon ethanol drinking, as shown in Ruiz-Leyva et al (2022), are found in females and are modulated by IEA at adolescence. The present study filled this void by exposing female Wistar rats to an IEA procedure at adolescence; and then assessed ethanol selfadministration via an adapted version of the "binge eating to binge drinking" model (Ruiz-Leyva et al, 2022).…”