Fig. 2.

Biosynthesis of neurosteroids. a A schematic diagram showing key enzymes involved in the conversion of DHEAS to testosterone. b Age-related changes in the expression of STS, 3BHSD2, but not 17BHSD5, in the rhesus macaque hippocampus, as determined by quantitative real-time PCR. Note that testosterone can be further converted to estradiol by aromatization. Together, these findings suggest neurosteroidogenesis is likely to be impacted by aging. Data adapted from Sorwell et al. (2011)