Early postnatal alcohol exposure that produces high blood alcohol levels impairs development of spatial navigation learning

Abstract

Artificial rearing procedures were used to expose groups of rats to alcohol during Postnatal Days 4 to 10. A 6.6-g/kg daily dose of ethanol was given either in a condensed fashion to induce cyclic daily blood alcohol concentrations (BACs) with high peaks or in a uniform fashion to induce stable, moderate daily BACs. Control groups included a gastrostomized, artificially reared group not exposed to alcohol and a suckle group. All artificially reared pups were fostered back to a dam on Postnatal Day 12. Beginning on Postnatal Day 19, the rats were tested daily in the Morris maze spatial navigation task. All measures of spatial navigation performance indicated that the group given the condensed alcohol exposure was significantly impaired in acquisition of spatial navigation. The group given uniform alcohol exposure differed only mildly from the control groups. The impairment of place learning of the condensed alcohol group suggests that the development of the hippocampal formation may have been impaired, consistent with findings that the neuromorphology of the hippocampus is significantly affected by condensed early postnatal alcohol exposure.