The effect of gonadectomy and sex steroid replacement on steroid conversion enzyme mRNA expression in adolescent male rat substantia nigra. (A). Cyp19A1 mRNA was decreased by gonadectomy and this was not prevented by T, DHT or E replacement. * denotes comparisons with Intact, * = p < 0.05, ** = p < 0.01 (B). 5αR-1 mRNA was increased by DHT compared to the Intact group but not by T or E replacement. ** p = < 0.01.