Enhanced alcohol intake after alcohol fetal exposure in the rat: the role of the opioid system.

CHOTRO, M.G; ARIAS, C

Canada

Congreso; 24th Annual Scientific Meeting of the Research Society on Alcoholism; 2001

Research Society on Alcoholism

Previous studies have shown that the administration of a moderate alcohol dose during gestational days 17-20 in the rat results in enhanced alcohol consumption by the offspring, when tested on preweanling stages. During this last gestational period the rat fetus can perceive chemosensory characteristics of substances present in the amniotic fluid, and these experiences may modify their subsequent preference for those flavors through associative or non-associative processes. It is also known that at this stage the opioid system is functional and that the opioid antagonist Naloxone can modify fetal responses known to be regulated through this system. Finally, biochemical and behavioral data indicate that opiate antagonists may reduce reinforcing properties of alcohol. Taking all this into account, it was hypothesized that the effect of increased alcohol intake as a consequence of prenatal ethanol exposure could obey to a conditioned preference resulting from the association between sensory and reinforcing properties of alcohol mediated by the opioid system. The present experiment was assessed to test this hypothesis. Pregnant rats received through gestational days 17-20 one daily intragastric administration of either a 2 g/kg ethanol dose (E) or water (W). Immediately following these administrations half of the dams of each group received a subcutaneous injection of a 10mg/kg Naloxone (Nal) dose while the remaining dams were injected with a saline isotonic solution (Sal). On postnatal day 14 all pups were tested in their consumption of either an alcohol solution (6%) or water. Results show that infants prenatally exposed to only alcohol (E-Sal) consumed significantly more alcohol than water and also showed higher alcohol intake when compared to pups from group W-Sal. Subjects from group E-Nal, however, did not show this increased ethanol intake in comparison to W-Nal treated pups or to any of the remaining two groups. Intake of water was equivalent for all groups. These results suggest that the opioid system plays an important role in the augmented alcohol intake effect observed after prenatal alcohol exposure. Also seem to support the hypothesis of a conditioned preference response established in utero after maternal alcohol administration. However, it can not be discarded that this increased alcohol consumption during infancy could be the result of a sensitization of the opioid system as a consequence of the prenatal alcohol administration.