Caspase activity in newt spermatogonial apoptosis induced by prolactin andcycloheximide

We previously showed in vivo and in vitro, that among the spermatogenic sta ges of the newt, prolactin (PRL) induces apoptosis specifically in the penu ltimate stage of, secondary spermatogonia. In the current report, we demons trate in vitro that cycloheximide (CHX), an inhibitor of protein synthesis, induces morphological apoptotic changes similar to those caused by PRL, su ch as chromatin condensation and apoptotic body formation. Next, we found t hat Z-VAD-fmk, an inhibitor of various caspases, suppressed the apoptosis i nduced by PRL and CHX, but ICE inhibitor Ac-YVAD-CHO or caspase-3 inhibitor Ac-DEVD-CHO did not. As high caspase activity was present in extracts of t estes treated with CHX, we suggest that an unidentified caspase induces the morphological changes of apoptosis in newt spermatogonia. Mol. Reprod. Dev . 59:209-214, 2001. (C) 2001 Wiley-Liss, Inc.