Aging-induced changes in sex-steroidogenic enzymes and sex-steroid receptors in the cortex, hypothalamus and cerebellum.

We investigated age-induced changes in mRNA expression profiles of sex-steroidogenic enzymes and sex-steroid receptors in 3-, 12-, and 24-month-old male rat brain subregions [cerebral cortex (CC), hypothalamus (Hy) and cerebellum (CL)]. In many cases, the expression levels of mRNA decreased with age for androgen synthesis enzyme systems, including Cyp17a1, Hsd17b and Srd5a in the CC and CL, but not in the Hy. Estradiol synthase Cyp19a1 did not show age-induced decline in the Hy, and nearly no expression of Cyp19a1 was observed in the CC and CL over 3-24 m. Androgen receptor Ar increased in the Hy but decreased in the CC with age. Estrogen receptor Esr1 increased in the CC and Hy, and did not change in the CL with age. Esr2 did not change in the CC and Hy, but decreased in the CL with age. As a comparison, age-induced changes of brain-derived neurotrophic factor mRNA were also investigated.