DEVELOPMENTAL PATTERN OF Δ5 3β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN ISOLATED RAT LEYDIG CELLS

Article abstract of DOI:10.1016/0039-128X(80)90049-5

A direct method for determination of Δ⁵ 3β-hydroxysteroid dehydrogenase (3β-HSD) activity was employed in isolated Leydig cells (LC) derived from rats on fetal day 19 (F₁₉) and postnatal (N) days 1, 12, 24, 34 and 45 and adults.The activity of 3β-HSD in the adult LC was 1.15 +/- 0.02 (μmole/μg DNA/hr, mean +/- SEM, n=73).Activities in the other groups, expressed as a percentage of the respective adult control, were: F₁₉ - 38percent; N₁ - 39percent; N₁₂ - 8percent; N₂₄ - 89percent; N₃₄ - 166percent; and N₄₅ - 118percent.A good correlation was found between histochemical staining for 3β-HSD and the quantitative method employed.Using (3H)-DHA as a substrate, LC isolated from F₁₉, N₁ and N₁₂ produced testosterone in appreciable amounts (41percent, 55percent and 20percent of the total products respectively) whereas at advanced stages of development (N₂₄ to adulthood) the major product was androstenedione (93 +/- 1percent).These findings may be explained by the observed decrease in 17β-hydroxysteroid dehydrogenase (17β-HSD) activity, due to an insufficient supply of NADPH, in the older vs. earlier stages of development.This study indicates the presence of steroidogenic enzymatic activity in LC throughout development in the rat.It also provides a relatively simple in vitro model for studies of testicular regulation during development.