Effects of exposure to moderate levels of ethanol during prenatal brain development on dendritic length, branching, and spine density in the nucleus accumbens and dorsal striatum of adult rats

Abstract

Reductions in measures of dendritic morphology in the agranular insular cortex have been identified as consequences of prenatal exposure to moderate levels of ethanol in the rat. Motivated by the strong connectivity between this region of frontal cortex and the striatum and a growing body of data linking specific components of the mesocortical/limbic system to effects of ethanol and ethanol self-administration, the current study investigated the effects of moderate fetal ethanol exposure on the dendritic morphology of medium spiny neurons (MSNs) in several regions of the striatum. Throughout gestation, pregnant rat dams either consumed a saccharin solution (control) or achieved average daily blood ethanol concentrations of 84 mg% via voluntary consumption of a 5% ethanol solution. The brains of adult male offspring were extracted and processed for Golgi-Cox staining. MSNs from the dorsomedial striatum, dorsolateral striatum and the nucleus accumbens core and shell were sampled for analysis. Relative to saccharin controls, robust reductions in dendritic length and branching, but not spine density, were observed in the shell of the nucleus accumbens in fetal-ethanol-exposed rats. No significant prenatal ethanol effects were found in the other regions of the striatum. These findings suggest that exposure to moderate levels of ethanol in utero can have profound effects on brain regions related to reward processing and provide possible clues relevant to understanding increased self-administration of drugs of abuse in animals exposed to ethanol during brain development.