Cellular phenotype of androgen receptor-immunoreactive nuclei in the developing and adult rat brain

Androgen exposure during development and adulthood promotes cell-to-cell communication, modulates the size of specific brain nuclei, and influences hormone-dependent behavioral and neuroendocrine functions. Androgen action involves the activation of androgen receptors (AR). To elucidate the mechanisms involved in AR-mediated effects on forebrain development, double-label fluorescent immunohistochemistry and confocal microscopy were employed to identify the cellular phenotype of AR-immunoreactive (AR(+)) cells in the developing (embryonic day 20, postnatal days 0, 4, 10) and adult male rat forebrain. Sections were doubly labeled with antibodies directed against AR and one of the following: neurons (immature, nestin; mature, NeuN) or astrocytes [immature, vimentin; mature, glial fibrillary acidic protein (GFAP)] or mature oligodendrocytes (mGalC). In all brain regions examined, by far the majority of AR(+) cells were neurons. In addition, small subsets of AR(+) cells were identified as mature astrocytes (GFAP(+)) but only in specific brain regions at specific ages. AR(+)/GFAP(+) cells were observed in the cerebral cortex but only in postnatal day 10 rats and in the arcuate nucleus of the hypothalamus but only in adult rats. Immature neurons, immature astrocytes, and oligodendrocytes were not AR(+) at any age, in any region. Thus, both neurons and astrocytes in the male rat forebrain contain ARs, suggesting that androgens, via ARs, may exert effects on both cell types in an age- and region-dependent manner.