Effect of estradiol treatment on beta-endorphin content and release in the female rat hypothalamus.
The purpose of the present study was to determine whether an injection of estradiol valerate or chronic estradiol treatment alters beta-endorphin-immunoreactive (IR) material in the hypothalamus. Hypothalamic beta-endorphin-IR material was significantly reduced (by 47%) 2 months following an estradiol valerate injection. In addition, both the basal and veratridine-evoked release of beta-endorphin-IR material from hypothalamic slices incubated in vitro were decreased 48% and 52%, respectively. The net release of beta-endorphin-IR material was decreased by 50% compared to control animals. Chronic estradiol treatment (2 months) did not alter the tissue content of beta-endorphin-IR material. Although, we noted a significant decrease (48%) of the basal release and a significant increase (45%) of the evoked release, the net release of beta-endorphin-IR material from slices was not altered (107% of control). The present results suggest that estradiol valerate treatment decreases the capacity of beta-endorphin neurons in the hypothalamus to synthesize and maintain the release of beta-endorphin.
Lapchak
P A
PA
Department of Neurology and Neurosurgery, McGill University, Montreal, Que., Canada.
D000818:Animals; D004343:Drug Implants; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D004966:Estrogens, Conjugated (USP) / Q000494:pharmacology; D005260:Female; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D014701:Veratridine / Q000494:pharmacology; D001615:beta-Endorphin / Q000378:metabolism*
D004343:Drug Implants; D004966:Estrogens, Conjugated (USP); D004958:Estradiol; D001615:beta-Endorphin; D014701:Veratridine