Effects of estradiol on intact and denervated striatal dopamine receptors and on dopamine levels: a biochemical and behavioral study.
The present study describes the effect of chronic estrogen treatment on striatal dopamine levels and dopamine receptors, as well as on apomorphine-induced circling, a behavioral model reflecting dopaminergic activity in the rat striatum. Although estradiol itself does not show any affinity for the striatal dopamine receptor, its administration for 2 weeks in adult ovariectomized rats leads to a small increase in [3H]spiroperidol, [3H]haloperidol, and [3H]apomorphine binding in the striatum; this increase is associated with a greater number of binding sites. In order to dissociate possible pre- and post-synaptic effects of estrogens, these studies were next performed in animals bearing an unilateral 6-hydroxydopamine lesion of the substantia nigra. The apomorphine-induced circling behavior of rats bearing such a lesion was not affected by estrogen treatment. Estradiol treatment induced an increase of [3H]spiroperidol binding in both the intact and lesioned striatum, thus suggesting an estrogenic effect on a population of postsynaptic receptors. Chronic estradiol treatment reduced the concentration of dopamine in the striatum while the turnover of this amine measured using alpha-methyl-p-tyrosine remained unchanged. The present results show that estradiol exerts effects at the striatal level on both dopamine metabolism and receptor levels.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D002369:Castration; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D003714:Denervation; D004298:Dopamine / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013239:Stereotyped Behavior / Q000187:drug effects
D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D004958:Estradiol; D001058:Apomorphine; D004298:Dopamine