Anatomic relationships between aromatase and androgen receptor mRNA expression in the hypothalamus and amygdala of adult male cynomolgus monkeys

This study mapped the regional locations of cells expressing cytochrome P45 0 aromatase (P450(AROM)) and androgen receptor (AR) mRNAs in the adult male macaque hypothalamus and amygdala by in situ hybridization histochemistry using monkey-specific cRNA probes. High densities of P450(AROM) and AR mRNA -containing neurons were observed in discrete hypothalamic areas involved i n the regulation of gonadotropin secretion and reproductive behavior. P450( AROM) mRNA-containing neurons were most abundant in the medial preoptic nuc leus, bed nucleus of the stria terminalis, and anterior hypothalamic area, whereas AR mRNA-containing neurons were most numerous in the ventromedial n ucleus, arcuate nucleus, and tuberomamillary nucleus. Moderate to heavily l abeled P450(AROM) mRNA-containing cells were present in the cortical and me dial amygdaloid nuclei, which are known to have strong reciprocal inputs wi th the hypothalamus. Heavily labeled P450(AROM) mRNA-containing cells were found in the accessory basal amygdala nucleus, which projects to the cingul ate cortex and hippocampus, areas that are important in the expression of e motional behaviors and memory processing. In contrast to P450(AROM), the hi ghest density of AR mRNA labeling in the temporal lobe was associated with the cortical amygdaloid nucleus and the pyramidal cells of the hippocampus. All areas that contained P450(AROM) mRNA-expressing cells also contained A R mRNA-expressing cells, but there were areas in which AR mRNA was expresse d but not P450(AROM) mRNA. The apparent relative differences in the express ion of P450(AROM) and AR mRNA-containing neurons within the monkey brain su ggests that T acts through different signaling pathways in specific brain a reas or within different cells from the same region. (C) 2001 Wiley-Liss, I nc.