[Effect of c-myb on hCG-induced testosterone secretion in isolated rat Leydig cells]

The present study was carried out to investigate the effect of antisense c-myb oligodeoxynucleotides (ODN) on hCG-induced testosterone secretion in isolated rat Leydig cells. The effects of cAMP, Ca(2+) and cycloheximide (CYX) on c-Myb protein expression and testosterone secretion were also observed. The results showed that antisense c-myb ODN inhibited hCG-induced testosterone secretion of isolated rat Leydig cells in a dose-dependent manner. At the same time, integral optical density immunostaining of Myb in Leydig cells was also remarkably reduced. Nonsense tat ODN had no effect on Leydig cells. Further experiments showed that dbcAMP (100 micromol/L) obviously increased hCG-induced testosterone secretion and integral optical density (IOD) immunostaining of Myb in Leydig cells. Verapamil (10 micromol/L), a Ca(2+) channel blocker, and cycloheximide (50 microg/ml), a protein synthesis inhibitor, reduced the immunostaining of c-Myb, and also lowered hCG-induced testosterone secretion in isolated rat Leydig cells. The results indicate that c-myb closely correlates with hCG-induced testosterone secretion, and that cAMP and Ca(2+)-dependent pathway participates in the expression of protooncogene.