Rapid stimulation of striatal dopamine synthesis by estradiol

INTRODUCTION All the data from clinical and animal research clearly indicated that the estrogens affect the nigrostriatal dopamine (DA) function as well as behaviors mediated by striatal DA (see Van Hartesveld and Joyce, 1986, for review). So far, on the other hand, no consensus has been reached regarding either the locus, the direction or the mechanism of estrogen actions. Actually, depending on the dose of estrogen administered, the duration of treatment, the time interval between estrogen treatment and testing, the behavior measured and the part of the basal ganglia from which the behavior is elicited, estrogens appear either to enhance or to suppress striatal dopaminergic transmission. Thus, in an attempt to determine the nature of direct estrogen effects on the presynaptic component of the nigrostriatal dopamine system, the present studies were designed (1) to examine the effect of an acute physiological dose of estradiol (E2) on the in viva rate of DOPA accumulation in the striatum after i.p. administration of NSD 1015 and (2) to determine in viva whether E2 might act directly on the striatum to modulate DA synthesis and/or release, when delivered locally by means of a push-pull cannula.