Effects of testosterone and progesterone on brain 5 α-reductase and aromatase in Long–Evans males and comparison of aromatase in Long–Evans vs. Sprague–Dawley rats

Abstract

We investigated medial basal hypothalamic–preoptic area (MBH–POA) 5 α-reductase and aromatase enzyme activities in gonadally intact and castrated adult Long–Evans (L–E) male rats treated with testosterone (T), progesterone (P), and a combination of T+P. MBH–POA 5 α-reductase and aromatase activities did not differ significantly among the groups. The lack of a difference in MBH–POA aromatase between control and castrated L–E animals was unexpected. In two further experiments, MBH–POA aromatase was examined in intact and castrated L–E and Sprague–Dawley (S–D) rats, using direct and indirect assays. The activity in castrated S–D (but again, not in L–E) rats significantly decreased compared to control values. These data suggest that the absence of gonads does not decrease MBH–POA aromatase in adult L–E rats.