The effect of gonadectomy and sex steroid replacement on sex steroid receptor mRNA expression in adolescent male rat substantia nigra. (A) AR mRNA levels were increased by T, DHT and E compared to Intact (*) and Gdx (#) groups (n=12-14/group). (B) ERα mRNA was decreased by DHT replacement compared to the Intact group. T and E did not change ERα mRNA levels and were significantly different to the DHT treated group. (C) ERβ mRNA was increased by T (compared to Intact and Gdx groups) and by DHT (compared to Gdx only), but not by E. *=p < 0.05, **=p < 0.01, *** and ###=p < 0.0001.