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

Abstract

This study mapped the regional locations of cells expressing cytochrome P450 aromatase (P450AROM) 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 P450AROM and AR mRNA-containing neurons were observed in discrete hypothalamic areas involved in the regulation of gonadotropin secretion and reproductive behavior. P450AROM mRNA-containing neurons were most abundant in the medial preoptic nucleus, bed nucleus of the stria terminalis, and anterior hypothalamic area, whereas AR mRNA-containing neurons were most numerous in the ventromedial nucleus, arcuate nucleus, and tuberomamillary nucleus. Moderate to heavily labeled P450AROM mRNA-containing cells were present in the cortical and medial amygdaloid nuclei, which are known to have strong reciprocal inputs with the hypothalamus. Heavily labeled P450AROM mRNA-containing cells were found in the accessory basal amygdala nucleus, which projects to the cingulate cortex and hippocampus, areas that are important in the expression of emotional behaviors and memory processing. In contrast to P450AROM, the highest 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 P450AROM mRNA-expressing cells also contained AR mRNA-expressing cells, but there were areas in which AR mRNA was expressed but not P450AROM mRNA. The apparent relative differences in the expression of P450AROM and AR mRNA-containing neurons within the monkey brain suggests that T acts through different signaling pathways in specific brain areas or within different cells from the same region.

Basal testosterone moderates responses to anger faces in humans

“…These effects of T may be mediated in part through the amygdala, which is highly responsive to threat signals [25,26] and contains androgen receptors [69,70]. In fact, preliminary evidence from fMRI studies conducted in our laboratory (unpublished data) and by others [71] suggest a relationship between T and amygdala responsiveness to anger faces.…”

Steroids control the aromatase gene expression in purified germ cells from the adult male rat

“…Data have been reported showing a positive role for androgens in aromatase expression in rat testicular somatic cells; these studies were in the presence of a saturating amount of testosterone (200 ng/ml) (Levallet & Carreau 1997, Genissel & Carreau 2001. Moreover in the rat brain (Roselli & Resko 1984) as well as in the brain of male rhesus monkeys (Resko et al 2000) androgens regulate aromatase at both the transcriptional level and the enzyme activity via the presence of ARs (Roselli et al 2001). In male gonad the localization of AR is a subject of controversy (for review see Eddy 2002); some reports have demonstrated the presence of immunoreactive AR in germ cells (Vornberger et al 1994, Zhou et al 1996 and other studies have shown that only testicular somatic cells express AR (Suarez-Quian et al 1999).…”

Testosterone and human behavior: the role of individual and contextual variables

“…During the past decade, pharmacological challenge studies indicate that a single dose of [11,12]; (2) these subcortical brain structures are rich in both androgen and estrogen receptors [30,31,32]; and (3) these regions play a key role in potentiating reactive aggression in animals [33]. Studies outside the scanner have also yielded interesting effects of testosterone on social cognition and behavior.…”