Neuroactive steroids modulate in vivo the Mg2+/Ca(2+)-ATPase activity in rat cortical and cerebellar synaptosomal membranes.

Estradiol and pregnenolone sulfate administered in vivo inhibited the Mg2+/Ca(2+)-ATPase activity in synaptosomal membranes from rat cortex by 20% and 30%, respectively. In cerebellum, estradiol decreased the activity up to 43%. The calmodulin-stimulated activity declined in cortex after treatment with estradiol and pregnenolone sulfate, but significantly increased in cerebellar membranes. Dehydroepiandrosterone sulfate had influence neither on enzyme activity, nor on stimulation by calmodulin in both examined rat brain regions.