Age-related changes in brain and pituitary 5 alpha-reductase with finasteride (Proscar) treatment.

Finasteride (Proscar), a 5 alpha-reductase inhibitor, was administered with or without 5 alpha-dihydrotestosterone (DHT) in juvenile (28), peripubertal (48), or young adult (68-day-old) male rats. Luteinizing hormone (LH) levels and ventral prostate (VP) weights monitored the efficacy of the treatments. For each postnatal day tested, LH hormone levels were not significantly altered by finasteride, suggesting that 5 alpha-reductase inhibition does not modulate LH in male rats using this protocol. Finasteride plus DHT treatment significantly decreased LH levels. Conversely, VP weights were significantly decreased in finasteride-treated animals while finasteride plus DHT treatment significantly increased VP values. Finasteride plus DHT treatment significantly decreased pituitary, but not brain, 5 alpha-reductase for each postnatal day tested. In finasteride-treated animals, hypothalamic and pituitary 5 alpha-reductase were significantly inhibited in young adult animals, whereas the activities were not altered in juvenile or peripubertal male rats. These data suggest that a different mechanism may regulate 5 alpha-reductase with the aging of the central nervous system and pituitary.