title: Functional role of caspases in heat-induced testicular germ cell apoptosis.
abstract: In the present study, we determined whether a pan caspase inhibitor could prevent or attenuate heat-induced germ cell apoptosis. Groups of five adult (8 wk old) C57BL/6 mice pretreated with vehicle (DMSO) or Quinoline-Val-Asp (Ome)-CH2-O-Ph (Q-VD-OPH), a new generation broad-spectrum caspase inhibitor, were exposed once to local testicular heating (43 degrees C for 15 min) and killed 6 h later. The inhibitor (40 mg/kg body weight) or vehicle was administered intraperitoneally (i.p.) 1 h before local testicular heating. Germ cell apoptosis was detected by TUNEL assay and quantitated as number of apoptotic germ cells per 100 Sertoli cells at stages XI-XII. Compared with controls (16.8 +/- 3.1), mild testicular hyperthermia within 6 h resulted in a marked activation (277.3 +/- 21.6) of germ cell apoptosis, as previously reported by us. Q-VD-OPH at this dose markedly inhibited caspase 3 activation and significantly prevented (by 67.0%) heat-induced germ cell apoptosis. Q-VD-OPH-mediated rescue of germ cells was independent of cytosolic translocation of mitochondrial cytochrome c and DIABLO. Electron microscopy further revealed normal appearance of these rescued cells. Similar protection from heat-induced germ cell apoptosis was also noted after pretreatment with minocycline, a second-generation tetracycline that effectively inhibits cytochrome c release and, in turn, caspase activation. Collectively, the present study emphasizes the role of caspases in heat-induced germ cell apoptosis.
authors.affiliation: Division of Endocrinology, Department of Medicine, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, David Geffen School of Medicine at UCLA, Torrance, California 90509, USA.
authors.forename: Yanira
authors.initials: Y
authors.lastname: Vera
authors.forename: Susana
authors.initials: S
authors.lastname: Rodriguez
authors.forename: Mark
authors.initials: M
authors.lastname: Castanares
authors.forename: Yanhe
authors.initials: Y
authors.lastname: Lue
authors.forename: Vince
authors.initials: V
authors.lastname: Atienza
authors.forename: Christina
authors.initials: C
authors.lastname: Wang
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Swerdloff
authors.forename: Amiya P
authors.initials: AP
authors.lastname: Sinha Hikim
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005854:Germ Cells / Q000201:enzymology*; D006358:Hot Temperature; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008911:Minocycline / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D013737:Testis / Q000166:cytology / Q000201:enzymology*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D011804:Quinolines; C468548:quinoline-val-asp(OMe)-CH2-OPH; D020169:Caspases; D008911:Minocycline