Developmental response by Leydig cells to acidic and basic fibroblast growth factor.

The present study examines the effects of acidic (FGF-1) and basic (FGF-2) fibroblast growth factors on Leydig cell steroidogenesis by cells from 5-, 21- and 90-day-old rats. These ages represent three distinct time points in Leydig cell development: fetal Leydig cells (day 5), immature Leydig cells (day 21) and adult Leydig cells (day 90). The results demonstrate that the actions of the two growth factors on steroidogenesis are developmentally regulated, and require the presence of heparan sulphate proteoglycans (HSPG). FGF-1 and FGF-2 both had stimulatory effects on basal, but not maximally LH-stimulated, testosterone production by fetal Leydig cells, and both growth factors stimulated basal 5 alpha-androstane-3 alpha, 17 beta-diol production by immature Leydig cells. These effects were mediated by heparan sulphate-proteoglycans (HSPG), as they were blocked by the addition of protamine sulphate and sodium chlorate. FGF-1 and FGF-2 had no effect on basal testosterone production by adult Leydig cells, however, FGF-1 alone inhibited LH-stimulated testosterone production by adult Leydig cells in a dose-dependent manner. These data demonstrate that the effects of FGF-1 and FGF-2 are dependent on the specific stage of Leydig cell differentiation and development and may vary accordingly. Furthermore, although FGF-1 and FGF-2 are closely related structurally, a different effect of these two growth factors can be observed on the same type of Leydig cells. The data therefore suggest that these growth factors may have different but specific roles in the regulation of Leydig cell steroidogenesis, at different stages of development.