title: Rapid effects of gonadal steroids upon hypothalamic neuronal membrane ultrastructure.
abstract: Freeze-fracture methodology was used to study rat hypothalamic arcuate nucleus (AN) neuronal plasma membrane organization following in vitro perfusion of brain slices with 17-beta-estradiol (17 beta E2) or other test compounds. Physiological levels (10(-10) M) of 17 beta E2 caused an increase in neuronal membrane exo-endocytotic pits within 1 min of perfusion. The increased density of pits was dose related, sustained at a constant rate during 10 min of perfusion, reverted to control values after perfusion with estradiol-free medium for 1 h, and was accompanied by an increased uptake of horseradish peroxidase by the arcuate nucleus in brain slices. The 17 beta E2-induced increase in exo-endocytotic pit density was blocked by tamoxifen (10(-8) M). Cholesterol (10(-10) M), 17-alpha-estradiol (10(-6) M) or dihydrotestosterone (10(-6) M) had no effect on exo-endocytotic pit density. Testosterone had about 50% the potency of 17 beta E2 in increasing exo-endocytotic pit density. These results indicate that physiological levels of 17 beta E2 can have rapid effects upon arcuate nucleus neuronal membrane ultrastructure.
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects* / Q000648:ultrastructure; D002462:Cell Membrane / Q000187:drug effects* / Q000648:ultrastructure; D002784:Cholesterol / Q000494:pharmacology; D003034:Coated Pits, Cell-Membrane / Q000187:drug effects / Q000648:ultrastructure; D013196:Dihydrotestosterone / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005614:Freeze Fracturing; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013629:Tamoxifen / Q000494:pharmacology; D013739:Testosterone / Q000494:pharmacology
chemical_list: D013196:Dihydrotestosterone; D013629:Tamoxifen; D013739:Testosterone; D004958:Estradiol; D002784:Cholesterol