title: GABA[A] receptor level changes in female hamster forebrain following in vivo estrogen progesterone and benzodiazepine treatment: a quantitative autoradiography analysis.
abstract: The levels of gamma amino butyric acid (GABAA) receptors (i.e. 3H-Muscimol binding sites) were determined by quantitative neurotransmitter receptors autoradiography in ovariectomized (OVX), OVX-estradiolo (E), OVX-progesterone (P), OVX-E + P, diazepam (DZ) and DZ + Ro15-1788 treated female hamsters. The various hormonal treatments altered 3H muscimol binding in many brain areas, whereas DZ and DZ + Ro15-1788 had little influence on GABAA receptor levels at the onset of the blocked aggressive behavioral activity. For example, E, P and E + P all significantly increased 3H muscimol binding in medial preoptic area, ventromedial hypothalamic nuclei, and vertical diagonal bandmedial septal nucleus, whereas P treatment increased binding in the caudate-putamen and decreased it in reuniens nucleus of the thalamus. E and E + P treatments increased 3H muscimol binding in the corticomedial amygdala nucleus and hippocampus. Diazepam treatment decreased the GABAA receptor binding in the caudate-putamen and basolateral amygdala, while having no effect in the other brain regions where hormone treatment was effective. In vitro incubation of brain sections with micromolar concentrations of E or P did not change muscimol binding. These results suggest that ovarian steroids, and benzodiazepines to a lesser extent, modulate 3H muscimol binding but do so in different brain regions. The hormone effects on 3H muscimol binding in the critical reproductive centres at a time period that coincides with the onset of its behavioral effect is consistent with a genomic controlled activity.
authors.affiliation: Laboratoria di Zoologia, Università della Calabria, Cosenza, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Canonaco
authors.forename: L H
authors.initials: LH
authors.lastname: O'Connor
authors.forename: D W
authors.initials: DW
authors.lastname: Pfaff
authors.forename: B S
authors.initials: BS
authors.lastname: McEwen
mesh_terms: D000818:Animals; D001345:Autoradiography; D001569:Benzodiazepines / Q000494:pharmacology; D006224:Cricetinae; D003975:Diazepam / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005442:Flumazenil / Q000494:pharmacology*; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism*; D009118:Muscimol / Q000378:metabolism; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*
chemical_list: D011963:Receptors, GABA-A; D001569:Benzodiazepines; D009118:Muscimol; D005442:Flumazenil; D011374:Progesterone; D004958:Estradiol; D003975:Diazepam