Testing the early alcohol debut effect: alcohol drinking, anxiety response and short-memory abilities in adolescent and adult rats exposed to binge drinking

SUAREZ, A; CENDÁN, CRUZ MIGUEL; PAUTASSI RM; LUQUE, MARIBEL; MORON V; SALGUERO, AGUSTÍN; RUIZ-LEYVA, L.

Congreso; 2020 Virtual Poster Sessions of the Research Society on Alcoholism (RSA); 2020

Research Society on Alcoholism (RSA)

Epidemiological studies have indicated that the earlier the age of first alcohol (ethanol) use the greater the likelihood of subsequent alcohol use disorders. The mechanisms underlying this phenomena (which may not be casually associated) are relatively unknown. We induced binge ethanol drinking in adolescent [postnatal days (PDs) 30-56] and adult (PDs 70-96) Wistar rats, and assessed the effects of this exposure upon two-bottle ethanol intake and preference, anxiety response, exploratory behaviors and short-term memory abilities. Adolescent and adult, male or female, rats self-administered 8-10% (v/v) ethanol three times a week for 4 weeks (from 700 to 900 PM, BINGE group), or were only handled (CONTROL group) or were given ethanol intraperitoneal administrations of ethanol (I.P. group) at doses that matched those self-administered by the BINGE group. A two-bottle (24 h long) choice test (ethanol vs. water) was conducted shortly before and shortly after exposure to the binge protocol. AT PD 100 the rats were tested for exploratory activity, anxiety response and short-term memory in the open field test, the concentric square field (CSF) and the novel-object recognition test. On PDs 120-134 the rats were tested for free-choice ethanol drinking. Adolescents exhibit significantly greater ethanol binge drinking than did adults (2.5-3.0 vs 1.25 g/kg, approximately), and effect that was inhibited by naloxone, administered 30-min before each binge. Blood ethanol levels in the adolescents, at binge session 3, were 60.82±22.39 mg/dl. Binge ethanol drinking at adolescence, but not at adulthood, significantly reduced exploratory activity in the open field, increased exploration of novel objects and increased anxiety response in the CSF. Ethanol exposure at PDs 30-56 (adolescence) induced, regardless the mode of exposure, significantly greater ethanol intake at PDs 120-134, when compared to peers that had ethanol exposure at PDs 70-96 (adulthood). The study indicates that adolescents are more prone than adults to exhibit binge-like ethanol drinking, and that binge ethanol ? in adolescents only ? alters exploratory activity and exacerbates anxiety. Ethanol exposure at adolescence was associated with significantly greater free-choice drinking at PDs 120-134, when compared to rats that were first exposed to ethanol at adulthood. Delaying alcohol access to adolescents should mitigate the likelihood of problematic alcohol use or alcohol-related consequences.