Dose response, ethanol-induced locomotor activity after stress exposure in adolescent and adult rats.

MARÍA B ACEVEDO; SPEAR, N.E.; PAUTASSI RM; SPEAR LP

Valparaiso

Workshop; II International Workshop: Motivated behaviors, stress and addiction: from molecules to behavior?; 2012

Latin America Research Network in Drug Abuse

Aim: The present experiment examined whether adolescent and adult rats differ in their susceptibility to ethanol-induced locomotor activity (LMA), and if this effect was affected by stress. Methods: At postnatal day (PD) 28 or 70 (adolescents and adults, respectively), rats were exposed to restraint or social isolation (90 min each treatment), or remained untreated. They were subsequently administered ethanol (1.25, 2.5 or 3.5 g/kg; i.g.) or vehicle, and assessed for ethanol-induced LMA for 15 minutes (post-administration time 5?19) in an inescapable novel environment. Results: Ethanol induced a dose-dependent stimulating effect in the adolescents, which did not exhibit behaviors indicative of motor depression. On the other hand, adults exhibited only a transient motor activation, followed by strong dose-response sedative effect that lasted throughout the test. Adolescents seemed relatively insensitive to stress; adults, on the other hand, exhibited heightened overall locomotion after isolation. There were no age-related differences in brain ethanol levels after ethanol administration, yet blood ethanol concentrations were significantly higher in adolescents than in adults. Conclusions: We observed age-related differences in sensitivity to ethanol-induced LMA and in sensitivity to stress. Ethanol-induced LMA was not affected by stress exposure, neither in adolescents nor in adults.