Early neonatal stress lessens sensitivity to ethanol-induced motor sedation

MACARENA FERNÁNDEZ; PAUTASSI RM

Huerta Grande

Congreso; XVIII Congreso anual de la Sociedad Argentina de Investigación en Neurociencias; 2013

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EARLY NEONATAL STRESS LESSENS SENSITIVITY TO ETHANOL-INDUCED MOTOR SEDATION FERNANDEZ, M.a,b; PAUTASSI, R.Ma,b. aInstituto de Investigación Médica M. y M. Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, C.P. 5000, Argentina b Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, C.P. 5000, Argentina macarenasoledadfernandez@gmail.com RESUMEN An early onset of alcohol consumption (Pilatti et al., 2013) and exposure to neonatal stress constitute vulnerability factors that promote problematic use of alcohol. A significant source of early stress comes are the alterations in quantity or quality of maternal care (Pautassi et al., 2008). The maternal separation paradigm (Plotsky and Meaney, 1993) is a model of early stress that has been shown to alter sensibility to the motivational (i.e., appetitive, aversive and negative reinforcing) effects of ethanol. These effects are important modulators of etanol-seeking and intake. Ethanol-induced motor activity has been used as a proxy for the appetitive effects of the drug. Alcohol induces biphasic motor effects, motor activation and depression, at low and high doses, respectively (Pautassi et al, 2009). In a previous Experiment of our lab we assessed etanol-induced motor activity in 15-day old infant rats that had been exposed to normal rearing conditions or that had experienced daily maternal separation [240 min per day] from postnatal day (PD) 1 to PD 14. Results indicated greater sensibility to etanol-induced activation (dose: 1.25 g/kg) in pups with history of maternal separation. The present study further analyzed behavioral activation induced by ethanol as a function of chronic maternal separation during PDs 1-14. On PD 15, animals were removed from the maternal cage and administered high-dose ethanol (2.5 g/kg). They were subsequently asssed in activity chambers during post-administration time 5-20 min. Data Analysis (ANOVA) indicated similar activating effects of 2.5 g/kg ethanol in control or maternally separated animals. Control animals, however, also exhibited a significant reduction in motor activity by the end of testing, when compared with vehicle-treated counterparts. This difference, indicative of ethanol-induced motor depression, was not observed in animals thah had been exposed to early neonatal stress. In other words, pups exposed to chronic maternal separation were insensitive to the sedative effects of ethe drug. Altogether, these results indicate that early neonatal stress alters the balance between the different motivational effects of ethanol. Specifically, stressed pups seems to be more sensitive to the behavioral activating effects of ethanol, but less sensitive to the motor depressing effects of ethanol.