THE EXPRESSION OF A PRENATAL ETHANOL EXPERIENCE IS MEDIATED BY THE OPIOID SYSTEM, IN 1 DAY-OLD RATS.

GUTTLEIN L; MÉNDEZ UBACH M.; ABATE P

Concepción

Congreso; INTERNATIONAL WORKSHOP First Joint Meeting Alcohol and other Drugs of Abuse: from molecules to human disorders; 2013

LASBRA/LARNEDA

Rat neonates rapidly acquire an operant response explicitly reinforced with ethanol. We evaluated the involvement of the opioid system in the expression of prenatal ethanol-related memories. In particular, we tested how the expression of an ethanol prenatal experience is modulated by mu opioid receptor system (MOR), employing an operant self administration paradigm in 1-day old newborns, prenatally exposed to moderate ethanol quantities. During gestational days (GDs) 17-20, dams were treated with ethanol (2 g/kg; i.g.) or water. On PD 1, 30-min before training, pups received an injection (i.p.) of CTOP (mu antagonist: 0.1 mg/kg), or vehicle. Afterwards, pups were tested in an operant learning procedure to obtain 3% ethanol. One hour later, an extinction session was performed. One pup received the reinforcer in contingency with the operant response, (Experimental pup; E). Simultaneously, when E-pup performed the operant response, a sibling received the reinforcer (Yoked pup; Y). Total number of responses (pressing with forelimbs or head a sensor key) was considered as dependent variable. Pharmacological blockade of mu opioid receptors, in those pups with prenatal ethanol experience, resulted in the absence of increases in instrumental response, when comparing with controlsaline subjects. This effect was observed during both, acquisition and extinction phases. Endogenous opioids, at least MOR system, are mediating the expression of a prenatal ethanol memory. These results suggest that, as could be observed in older pups, the opioid system modulates the reinforcing attributes of the drug in rat neonates in terms of consummatory and seeking behaviors.