Effects of an Indenopyridine Derivative, Compound 20–438, on Spermatogonial Stem Cells of the Rat

Single high doses of the antitesticular compound 20–438 caused pronounced testis weight loss in rats. Treatment of adult testes containing fully populated tubules led to irreversible weight losses, indicative of damage to the spermatogonial stem cells. On the other hand, treatment of lightly populated tubules in either juventile testes or adult, cryptorchid testes also caused weight losses, but these were followed by substantial recovery. The fact that the damage induced by 20–438 in spermatogonial stem cells is related to the germ cell density points to the possibility that this compound acts by reducing the availability of an essential substrate.