5α-Reductase activity regulates testosterone accumulation in two bands of immature cultured Leydig cells isolated on Percoll density gradients

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Abstract
The 5.alpha.-reductase inhibitor, 4-methyl-4-aza-2-oxo-5.alpha.-pregnan-20(s)-carboxylate was utilized to examine maturational changes in testosterone synthesizing capacity of Leydig cells localizing in Band 2 and Band 3 of Percoll density gradients. Immature Band 2 Leydig cells (from 25- to 39-day-old rats) cultured without the 5.alpha.-reductase inhibitor, produced increased testosterone in response to hCG or 8-br-cAMP; however basal, hCG-or 8-br-cAMP-stimulated testosterone accumulation was 4- to 12-fold higher when cells were cultured in the presence of inhibitor. Band 2 cells from older rats produced much less testosterone in reasponse to hCG or 8-br-cAMP (<3.5 pmol/105), even when cultured with the inhibitor. Although immature Band 3 cells cultured in the absence of 5.alpha.-reductase inhibitor produced increased testosterone in response to hCG or 8-br-cAMP, testosterone levels were relatively low, because elevated 5.alpha.-reductase prevented appreciable androgen accumulation; however, Band 3 cells from older rats (over 39 days old) accumulated progressively more testosterone, because of the age-dependent decline in 5.alpha.-reductase activity. Immature Band 3 cells cultured with the 5.alpha.-reductase inhibitor accumulated 20- to 44-fold more testosterone in response to hCG of 8-br-cAMP. Thus, testosterone levels in control, hCG- or 8-br-cAMP-treated Band 3 cells form 39-day-old rats were 61.5, 177.2, and 500.3 pmol/105 cells, respectively. Testosterone declined from these high immature levels; however, testosterone still was relatively high in Band 3 cells of 63-day-old animals (83.4 and 98.3 pmol/105 cells in response to hCG or 8-br-CAMP, respectively). These studies demonstrate the viability of Leydig cells localizing in Band 2, emphasize the role of 5.alpha.-reductase activity in regulting testosterone accumulation of Leydig cells in both Band 2 and Band 3 and demonstrate differences in the pattern of testosterone production with maturation in cultured Leydig cells in Band 2 and Band 3.