FIBROBLAST GROWTH-FACTOR RECEPTOR-TYPE 1 EXPRESSION DURING RAT TESTICULAR DEVELOPMENT AND ITS REGULATION IN CULTURED SERTOLI CELLS

In the present study, we examined the ontogeny of the type 1 receptor for basic fibroblast growth factor (FGFR-1) in whole rat testis, its c ellular localization, and its in vitro regulation in 20-day-old rat Se rtoli cells. Gene expression of FGFR-1 was developmentally regulated; expression was higher in prepubertal testes and decreased with sexual maturity. The transcript was found to be expressed in Leydig-enriched fractions, peritubular cells, Sertoli cells, and, to a lesser extent, germ cells. FSH as well as (Bu)(2)cAMP enhanced FGFR-1 messenger RNA ( mRNA) levels in cultured Sertoli cells, suggesting an involvement of t he protein kinase-A pathway. Addition of basic FGF (bFGF), tumor necro sis factor-alpha (TNF alpha), or interleukin-1 alpha resulted in a dos e and time-related increase in FGFR-1 mRNA levels. The effect of bFGF was specific, because it was neutralized by cotreatment with an anti-b FGF. We tested medium conditioned by germ cells and found a stimulatio n of the Sertoli cell FGFR-1 mRNA levels, which was abolished by immun odepletion of the conditioned medium with anti-TNF alpha antibodies. I t is suggested that in Sertoli cells, bFGF action, when mediated by FG FR-1, is under a complex hormonal (FSH) and paracrine and/or autocrine control exerted at least by bFGF, TNF alpha, and interleukin-1 alpha.