17 beta-Estradiol at a physiological dose acutely increases dopamine turnover in rat brain.

Ovariectomized rats injected with 17 beta-estradiol (30 ng, s.c.) showed an increase of the dopamine metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) with no change of dopamine concentrations in the striatum and nucleus accumbens. This increase was observed 30 min after the steroid injection and coincided with peak plasma 17 beta-estradiol concentrations. Plasma prolactin concentrations were not significantly elevated after 30 ng of 17 beta-estradiol. In ovariectomized rats with a unilateral lesion of the entopeduncular nucleus, the same dose of 17 beta-estradiol induced a postural deviation to the lesioned side with a maximum at 30 min. Thus, very small doses of estradiol were able to increase dopamine turnover. This effect was seen within minutes and was relatively short. It is probably non-genomic, presynaptic and similar to the effect of a small dose of a dopamine releasing agent.