Prenatal valproic acid exposure decreases neuronal membrane order in rat offspring hippocampus and cortex

Sprague-Dawley rats were administered 0 or 200 mg/kg of valproic acid (VPA) on days 7-18 of gestation. Controls were pair-fed. On postnatal day 28, analyses of brain tissues were performed on enriched neuronal membrane fractions from cerebellum, hippocampus, and cortex for anisotropy using the membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH). No significant differences in membrane anisotropy were noted in the cerebellum, but a significant reduction in anisotropy in the hippocampus and cortex was observed. This change corresponds to a 3-5 degrees C increase in temperature or that produced by other membrane disordering agents (ethanol, phenytoin). An association between membrane anisotropy and functional effects of prenatal VPA exposure is discussed.