title: The stimulatory effect on gonadotropin release of implants of estradiol or progesterone in certain sites in the central nervous system.
abstract: The sites of stimulatory feedback of ovarian steroids on gonadotropin release were examined. In estrogen-primed ovariectomized rats, estradiol or progesterone was implanted stereotaxically into various hypothalamic and extrahypothalamic areas. Both steroids elevated plasma LH and FSH levels at 6 h when implanted unilaterally into the preoptic-anterior hypothalamic area. Bilateral implants at this site were ineffective; presumably, this was due to the destructive lesion produced by the cannulae since in sham-implanted or anteriorly deafferented rats systemic estrogen was also ineffective. Unilateral estradiol implants in the medial basal hypothalamus elevated LH and FSH at 30 but not at 6 h. Maximum increases of plasma gonadotropins occurred 30 h after implantation of estradiol in the medial amygdaloid nuclei; progesterone implants at this site elevated only FSH at 6 h. Dissociation in the release of LH and FSH was also observed following implantation of estradiol into the hippocampus. Plasma FSH levels were dramatically reduced at 30 h while LH was slightly elevated. Progesterone implants in the hippocampus or medial basal hypothalamus did not alter plasma gonadotropin levels.
mesh_terms: D000679:Amygdala / Q000187:drug effects; D000818:Animals; D002369:Castration; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects; D008032:Limbic System / Q000187:drug effects*; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats
chemical_list: D004343:Drug Implants; D006065:Gonadotropins, Pituitary; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone