GABA[A] receptor level changes in female hamster forebrain following in vivo estrogen progesterone and benzodiazepine treatment: a quantitative autoradiography analysis |
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Authors: | M. Canonaco L. H. O'Connor D. W. Pfaff B. S. McEwen |
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Affiliation: | (1) Present address: Laboratoria di Zoologia, Università della Calabria, Via J.F. Kennedy, Roges di Rende, I-87036 Cosenza, Italy;(2) The Rockefeller University, 10021-6399 New York, NY, USA;(3) Department of Psychiatry, Washington University School of Medicine, 63110 St. Louis, MI, USA |
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Abstract: | Summary 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. |
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Keywords: | Female hamster Steroid hormone Benzodiazepines 3H-muscimol binding Quantitative autoradiography |
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