Abstract: Objective To investigate the influence on apoptosis of germs and expression of inducible nitric oxide synthase (iNOS) expression in male rats testis by administered with combination regimen of low-dose gossypol acetic acid(GA)with steroid hormones(desogestre/ethinylestradiol/testosterone undecanote(DSG/E/TU). Methods Adult male rats were randomly divided into four groups. Group GH：rats were fed orally with GA［125mg(kg.day)］and DSG［125μg/(kg.day)］/E［25μg/(kg.day)］/TU［100mg/(kg.day)］; Group G: rats were administered with a single dose of GA［125mg/(kg.day)］; Group H: rats were administered with DSG［125μg//(kg.day)］, E［25μg/(kg.day)］and TU［100mg/(kg.day)］; Group C: rats only received vehicle(1％ methyl cellulose). The testes were removed at 4,6,8 weeks respectively. TUNEL staining was observed. The expressions of iNOS were detected by immunohistochemical staining and Western blotting. Results The TUNEL positive stainings were found in the residual bodies in the methylcelluosetreated group(C) and in the pachytene spermatocytes nuclei in gossypol combined with steroid hormones group(GH). The amount of apoptosis cells were much larger in the GH group than that in the control group with treatment time increasing(EM>P/EM>0.01).iNOS was expressed constitutively in Leydig cells and in a stagede

Key words: Gossypol, Steroid hormone, iNOS, Germ, Immunohistochemistry, Western blotting, Rat