Basic fibroblast growth factor induces luteinizing hormone receptor expression in the presence of insulin-like growth factor-I in ovarian granulosa cells.
Effect of basic fibroblast growth factor (bFGF) on the expression of receptors for luteinizing hormone (LH), a marker of differentiation, was studied using estrogen-primed rat ovarian granulosa cells in primary culture. bFGF had no effect by itself but dose-dependently induced expression of functional LH receptors in the presence of insulin-like growth factor-I (IGF-I). The effect of a combination of bFGF and IGF-I was delayed in onset and the magnitude of the response was smaller when compared to the action of follicle-stimulating hormone (FSH). Scatchard analysis revealed that dissociation constant (Kd) and number of LH receptors induced by bFGF and IGF-I were 0.47 nM and 6.48 fmol/10(6) cells, respectively. Unlike FSH, bFGF plus IGF-I did not cause an immediate increase in cAMP release, however, considerable amount of cAMP release was observed in cells incubated for 72 h with bFGF plus IGF-I. Indomethacin, an inhibitor of cyclooxygenase, attenuated both LH receptor expression and cAMP release induced by bFGF plus IGF-I but had little effect on the action of FSH. Finally, a combination of bFGF and IGF-I increased production of prostaglandin E2 in granulosa cells. These results indicate that bFGF is capable of inducing LH receptor in the presence of IGF-I by a mechanism involving production of prostaglandin E2.
Kanzaki
M
M
Cell Biology Research Unit, Institute of Endocrinology, Gunma University, Maebashi, Japan.
Hattori
M
M
Horiuchi
R
R
Kojima
I
I
D000818:Animals; D002478:Cells, Cultured; D004347:Drug Interactions; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D006107:Granulosa Cells / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011974:Receptors, LH / Q000096:biosynthesis*
D011974:Receptors, LH; D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone