EXPRESSION OF 5-ALPHA-REDUCTASE IN THE HUMAN TEMPORAL-LOBE OF CHILDREN AND ADULTS

Androgens exert important biological effects on the brain, and 5 alpha -reductase plays a crucial role in androgen metabolism. Therefore, we investigated the expression of the two isozymes of 5 alpha-reductase i n the human temporal lobe to determine the predominant isoform and to elucidate the existence of possible sex differences and differences be tween children and adults. We studied biopsy materials from the tempor al lobe of 34 women, 32 men, and 12 children. Quantification of 5 alph a-reductase 1 and 2 messenger ribonucleic acid (mRNA) was achieved by competitive RT-PCR. 5 alpha-Reductase activity was determined in tissu e homogenates using [1,2-H-3] androstenedione as the substrate. Only 5 alpha-reductase 1 mRNA was expressed in human temporal lobe tissue; 5 alpha-reductase 2 mRNA was not expressed. 5 alpha-Reductase 1 mRNA co ncentrations did not differ significantly; in the cerebral cortex of w omen [25.9 +/-. 7.9 arbitrary units (aU) mean +/- SEM] and men (20.4 /- 2.8 all) or in the cerebral cortex (23.3 +/- 4.4 all) and the subco rtical white matter of adults (32.6 +/- 5.6 all), but they mere signif icantly higher in the cerebra; cortex of adults than in that of childr en (6.4 +/- 2.3 aU; P < 0.005). The apparent K-m of 5 alpha-reduction did not show significant differences between the two sexes. In conclus ion, 5 alpha-reductase 1 mRNA is expressed in the temporal lobe of chi ldren and adults, but 5 alpha-reductase 2 mRNA is not. Sa-Reductase 1 mRNA concentrations did not differ significantly in the sexes, but the y were significantly higher in specimens of adults than in those of ch ildren.