title: Estrogen receptor-beta colocalizes extensively with parvalbumin-labeled inhibitory neurons in the cortex, amygdala, basal forebrain, and hippocampal formation of intact and ovariectomized adult rats.
abstract: Estrogen has been reported to regulate the activity of gamma-aminobutyric acid (GABA)ergic interneurons within the hippocampus, basal forebrain, and hypothalamus of adult rodents. Although estrogen receptor-alpha bearing GABAergic interneurons have been identified previously, the neurotransmitter phenotype of cells that express the more recently characterized estrogen receptor-beta (ER-beta) has not been examined in vivo. We, therefore, have used fluorescent immunohistochemistry to further characterize the phenotype of ER-beta-bearing cells by double labeling for the GABAergic-associated calcium-binding protein, parvalbumin (PV). We find that a large proportion of ER-beta-immunoreactive cells within the cortex, amygdala, basal forebrain, and hippocampal formation of intact and ovariectomized (ovx) adult rats are PV-immunoreactive. Within the infralimbic, agranular insular, primary motor, parietal association, perirhinal, and lateral entorhinal cortices, an average of 95.6% +/- 0.8% (intact) and 94.5% +/- 1.4% (ovx) of all ER-beta-immunoreactive cells coexpress parvalbumin, and this proportion is strikingly similar across these diverse cortical regions. ER-beta/PV double-labeled cells represent 23.3% +/- 1.6% (intact) and 25.8% +/- 2.0% (ovx) of all PV-labeled cells within these regions. ER-beta/PV double-labeled cells are also observed within the lateral, accessory basal, and posterior cortical nuclei of the amygdala, and periamygdaloid cortex. Within the basal forebrain, 31.0% +/- 3.1% (intact) and 26.0% +/- 5.2 % (ovx) of ER-beta-immunoreactive cells coexpress PV. Almost all ER-beta-immunoreactive cells within the subiculum, a major output region of the hippocampal formation, double label for PV (intact = 97.2% +/- 2.8%; ovx = 100% +/- 0.0%). Thus, ER-beta exhibits extensive colocalization with a subclass of inhibitory neurons, suggesting a potential mechanism whereby estrogen can regulate neuronal excitability in diverse and broad brain regions by modulating inhibitory tone.
mesh_terms: D000679:Amygdala / Q000378:metabolism; D000818:Animals; D001479:Basal Ganglia / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D047629:Estrogen Receptor beta; D005260:Female; D006624:Hippocampus / Q000378:metabolism; D007395:Interneurons / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D010052:Ovariectomy; D010320:Parvalbumins / Q000378:metabolism; D016548:Prosencephalon / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D011960:Receptors, Estrogen / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D047629:Estrogen Receptor beta; D010320:Parvalbumins; D011960:Receptors, Estrogen; D005680:gamma-Aminobutyric Acid