Gonadotropin action on androgen synthesis in short-term incubation of explants and dispersed cells of the testis of Xenopus laevis

Testis cells of the toad Xenopus laevis were dissociated with collagenase and the cell suspension was enriched for steroidogenic cells by Percoll gradients. Results suggested that cells should be preincubated during a 6-h period before stimulation with gonadotropin. Our results indicate that a 2-h incubation period with gonadotropin was necessary to obtain a significant response. Furthermore, the cells can be maintained in a functional state longer than mammalian testis cells. Different gonadotropins were used to stimulate androgen production, and their effects were compared in both dissociated cells and testicular explants. Cells were more sensitive to luteinizing hormone (LH) and follicle stimulating hormone (FSH) than the explants (ED50LH = 0.041 +/- 0.003 micrograms for cells and 0.097 +/- 0.002 micrograms for explants: ED50FSH = 0.41 +/- 0.03 micrograms for cells and 0.63 +/- 0.03 micrograms for explants). Moreover, human chorionic gonadotropin (hCG) which only stimulates testicular explants at high doses, failed to stimulate the androgen production of dissociated cells; this indicates a low sensitivity of amphibian testis to hCG and a possible damaging effect of collagenase on the receptors of isolated cells.