GABA[a] receptor level changes in female hamster forebrain following in vivo estrogen progesterone and benzodiazepine treatment: a quantitative autoradiography analysis

• Published in: Experimental brain research 1989-05, Vol.75 (3), p.644-652
• Main Authors: CANONACO, M, O'CONNOR, L. H, PFAFF, D. W, MCEWEN, B. S
• Format: Article
• Language: English
• Subjects: Animals; Autoradiography; Benzodiazepines - pharmacology; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cricetinae; Diazepam - pharmacology; Estradiol - pharmacology; Female; Flumazenil - pharmacology; Frontal Lobe - drug effects; Frontal Lobe - metabolism; Fundamental and applied biological sciences. Psychology; Muscimol - metabolism; Ovariectomy; Progesterone - pharmacology; Receptors, GABA-A - drug effects; Receptors, GABA-A - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/BF00249916

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.