Adolescent but not adult alcohol initiation influence alcohol consumption after a short period of deprivation.

FABIO, M. C.; SPEAR, NORMAN; PAUTASSI, RICARDO MARCOS

San Francisco

Congreso; 35th RSA Annual Meeting; 2012

Background: It has been suggested that the earlier the onset of alcohol use – which usually occurs during adolescence – the greater the likelihood of later alcohol problems. We recently observed heightened alcohol consumption in adolescent rats that had been exposed to alcohol (5 or 2 intubations given every other day, dose: 2.5 g/kg) during early adolescence. The aim of the present study was to further explore the permissive effect of passive alcohol exposure on later alcohol intake and analyze if this effect is also observed during adulthood. Methods: A total of 32 adolescent (postnatal day 28 at the beginning of the procedures, PD 28; n=8 per group) and 28 (PD70; =7 per group) adult male Wistar rats were given intragastric (i.g.) administrations every other day. They received either 5 [5-day exposure group, ethanol on PDs 28, 30, 32, 34 and 36 (adolescents); or ethanol in PDs 70, 72, 74, 76, 78 (adults)], 2 [2-day exposure group: ethanol on PD 28 and 32, vehicle on PD 30, 24 and 36 (adolescents); or ethanol on PDs 70 and 74 and vehicle on 72, 76 and 78 (adults)] or 0 [control group treated with vehicle on PDs 28- 36 (adolescent); or 70–78 (adults)] administrations of 2.5 g/kg ethanol. Voluntary alcohol consumption was subsequently measured through a 24h, 2-bottle choice test (concentration: 5.6% alcohol, vehicle: 1% sucrose; ad-libitum food) at PDs 39-42 (adolescents) or PDs 80 to 83 (adults); and after a short period of alcohol recess at PD 50 or PD 91 (for adolescents and adults, respectively). We also tested anxiety response through a light/dark box test before commencement of self-administration and in the last day of alcohol recess. Results: Alcohol-initiated adolescent, but not adult, rats showed significantly greater alcohol consumption after a period of alcohol recess (PD50) than non-initiated animals. This facilitative effect of early exposure to alcohol was fairly similar in adolescents given 2 or 5alcohol intubations. These results do not seem to be associated with an ethanol-inducedexacerbated anxiety response, as there were no treatment differences in the dark/light boxtest at any developmental stage. Conclusions: Altogether, these results highlight the permissive role that alcohol exposureexerts on later alcohol intake. At least under the present experimental circumstances, this phenomenon seemed to be an early debut effect that occurred only when alcohol initiation begun at adolescence.