Prenatal cocaine increases dendritic spine density in cortical and subcortical brain regions of the rat.

Alterations in dendritic spine density following prenatal cocaine exposure were examined in the present study. Timed pregnant rats were injected daily with 30 mg/kg cocaine or saline during gestation. At postnatal day 21, male and female animals were separated and spine density was assessed following Golgi impregnation. In prenatal cocaine-exposed rats, significant increases in dendritic spine density were observed on pyramidal cells in the CA1 region of the hippocampus, basal dendrites of layer II/III of the medial prefrontal cortex, medium spiny neurons of the striatum and the core of the nucleus accumbens, as well as in neurons of the ventromedial hypothalamic nucleus. No differences were observed in either apical or basal dendrites of pyramidal cells in layer III of the sensory cortex or layer V of the medial prefrontal cortex, or in apical dendrites of layer II/III pyramidal cells of the medial prefrontal cortex. Moreover, there were no sex differences in any region examined. These results demonstrate that prenatal cocaine exposure increases spine density in many brain regions at postnatal day 21, and this effect is independent of sex.