CONICET | Buscador de Institutos y Recursos Humanos

Background: It is important to analyze age-related differences in sensitivity to ethanol, as they can underscore vulnerability factors for the development of alcohol-related problems. The present experiment examined ethanol-induced behavioral stimulation and alcohol intake in adolescent and adult rats. Methods: Adult and adolescent male Wistar rats were tested for ethanol-induced behavioral activation (2.5 g/kg, i.g.) in an open field and were then assessed for ethanol intake (vehicle: 1% sucrose) using a 16-day-long ethanol intake protocol. The protocol had four phases, each one 4 days long. Daily, two-bottle choice tests [ethanol vs. vehicle, test duration: 120 min] were conducted in Phase 1, whereas in Phase 2 animals were given 24 h access to ethanol as the only fluid. Phase 3 (alcohol deprivation) involved standard access to water and food and Phase 4 repeated the procedure of Phase 1. Results: Ethanol induced locomotor activation, which was fairly similar in adolescent and adults. Acute ethanol exposure did not alter later ethanol intake. Under conditions of limited access to the drug (i.e., Phases 1 and 4), adults drank significantly more ethanol than did adolescents. On the other hand, ethanol intake under the continuous, 24-h access condition (i.e., Phase 2) was significantly greater in adolescents than in adults. Both ages exhibited a significant increase in ethanol self-administration after the ethanol deprivation phase. Conclusions: Our expectation of greater ethanol-induced stimulation in adolescents than in adults was not corroborated. Both ages exhibited similar drug-induced motor stimulation. Patterns of voluntary alcohol consumption seemed to depend on the nature of testing conditions. Adolescents exhibited significantly greater ethanol intake than adults under conditions of continuous, 24-h access to ethanol. This pattern reversed when the drug was offered in a 2-h two-bottle intake test.