Stimulating effect of both human recombinant inhibin A and activin A on immature porcine Leydig cell functions in vitro.
In addition to the regulation of FSH secretion, it has been clearly shown that inhibin and activin have paracrine/autocrine effects in the gonads. We have studied the effect of human recombinant inhibin A and human recombinant activin A on immature porcine Leydig cells in vitro. Leydig cells were prepared by collagenase digestion of testes from 3-week-old piglets, purified on Percoll gradient, then cultured in a chemically defined medium. The cells were treated with increasing amounts of inhibin A or activin A (0.5-200 ng/ml). Direct application of either inhibin A or activin A on Leydig cells for 4 or 48 h did not stimulate basal testosterone secretion. Conversely, treatment of the cells for 48 h with either factor resulted in a dose-dependent increase in hCG-stimulated testosterone secretion (10[-9] M hCG, 2 h) with a maximal effect of 2.40 +/- 0.37- and 2.43 +/- 0.37-fold increases for inhibin A and activin A, respectively, and these changes were associated with a slight increase in LH/hCG-binding sites (1.37 +/- 0.19- and 1.24 +/- 0.11-fold increases). In addition, both inhibin A and activin A enhanced messenger RNA (mRNA) levels of LH/hCG receptor (2.75 +/- 0.40- and 2.53 +/- 0.60-fold increases) and cytochrome P450 17alpha-hydroxylase (6 +/- 1- and 3.5 +/- 0.6-fold increases), but had no effect on side-chain cleavage cytochrome P450 or cytochrome P450 aromatase mRNAs. 3beta-Hydroxysteroid dehydrogenase mRNA levels were increased (3.1 +/- 1.3-fold increase) by activin A, but not by inhibin A. However, inhibin A blocked the stimulatory action of activin A. In keeping with these changes in the steroidogenic enzyme mRNAs, both peptides enhanced the conversion of exogenous 22R-hydroxycholesterol and progesterone, but only activin A increased the conversion of dehydroepiandrosterone into testosterone. In conclusion, our findings demonstrate that both inhibin A and activin A have a stimulatory effect on immature porcine Leydig cell differentiated function in vitro. As inhibin has a stimulatory and activin has an inhibitory effect on rat Leydig cell function in vitro, the effects of these factors on Leydig cells seem to be species dependent.
Lejeune
H
H
INSERM-INRA U-418 and IFR D'Endocrinologie, Hôpital Debrousse, Lyon, France.
Chuzel
F
F
Sanchez
P
P
Durand
P
P
Mather
J P
JP
Saez
J M
JM
D028341:Activins; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D006801:Humans; D007265:Inhibins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D011974:Receptors, LH / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D013552:Swine; D013739:Testosterone / Q000378:metabolism
D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; D011974:Receptors, LH; D011994:Recombinant Proteins; D028341:Activins; D013739:Testosterone; D007265:Inhibins