Postnatal function following prenatal reserpine exposure in rats: Neurobehavioral toxicity

Abstract

Behavioral and neurochemical analyses were conducted on preweanling CD rats prenatally exposed to either 0, 0.375 or 0.750 mg/kg/day reserpine SC on gestation days 12–15. Offspring body weights were taken on test days, and pups were tested for negative geotaxis responding on postnatal day 8, developmental activity on days 12, 16 and 20, and auditory startle habituation on day 19 or 20. In addition, brains were removed from culled pups on day 1, 1 male and 1 female/litter on day 8, and animals tested for activity on day 21. Neurochemical assays were performed on whole brains from 1- and 8-day-old pups, and on caudate nucleus, frontal cortex and hippocampus of day 21 rats. Treatment resulted in dose-related decreases in maternal weight gain over gestation and mean pup weight at birth. Changes in the normal developmental activity pattern were both sex and dose dependent in treated rats. In auditory startle habituation experiments, rats exhibited a dose-related decrease in response amplitude and rate of habituation. In the day 21 females, caudate nucleus dopamine (DA) and serotonin (5-HT) concentrations and DA-receptor binding were decreased in a dose-dependent manner. Males showed less dramatic, but similar trends in caudate changes. However, hippocampal 5-HT and 5-HT receptor binding were significantly reduced only in females. Thus, sex-related behavioral alterations were accompanied by sex-related neurochemical changes, and females generally were more affected than males by prenatal reserpine treatment. The significant decrease in activity and auditory startle amplitude in the females is consistent with the suggested down regulation of the DA system in regional brain areas.