Article date: 1991/2/1
PubMed ID: 1848442
Journal name: The Journal of steroid biochemistry and molecular biology (ISSN: 0960-0760)
The specific binding of tritiated muscimol to gamma-aminobutyric acid (GABA) receptor sites was studied in distinct brain areas of female rats during different endocrine states. In diestrous rats with intact ovaries the highest receptor densities were found in the cortex (10.24 pmol/mg protein) and the lowest concentrations in the mediobasal hypothalamus (3.29 pmol/mg protein). Four weeks after removal of the ovaries, the number of binding sites was enhanced up to 2.4-fold in all brain areas investigated: the preoptic brain area, mediobasal hypothalamus, corticomedial amygdala, and cerebral cortex. The affinity of the binding sites remained unchanged. Substitution of estradiol and progesterone reduced the number of binding sites to values seen before ovariectomy. The induction of an afternoon surge of LH by estradiol that could be blocked by enhancing the GABAergic tone was accompanied by a distinct reduction in Bmax in the preoptic area in the morning. These results give evidence that ovarian hormones modulate GABAergic neurotransmission by regulation of GABAA receptor synthesis or degradation.
Author List: Jüptner M, Jussofie A, Hiemke C
Publication Types: Journal Article; Research Support, Non-U.S. Gov't
Substances mentioned in the article: Receptors, GABA-A; Tritium; Muscimol; Progesterone; Estradiol; Luteinizing Hormone;
Mesh terms: Animals; Brain/drug effects; Estradiol/pharmacology; Female; In Vitro Techniques; Luteinizing Hormone/blood; Muscimol/metabolism; Ovariectomy; Progesterone/pharmacology; Rats; Rats, Inbred Strains; Receptors, GABA-A/drug effects; Synaptic Transmission; Tritium;