Abstract: Objective To study the changes of testicular epidermal growth factor (EGF), chromogranin A(CgA)immunoreactive(IR) cells, and the changes of serum follicle-stimulating hormone（FSH）, luteinizing hormone（LH） level in rats during heroin withdrawal, methadone detoxification and heroin relapse, in order to investigate the mechanisms. Methods Sixty-three adult male SD rats were randomly divided into normal control group (NCG), saline control group (SCG),and experiment group (EG). The rats in the EG group were divided into heroin withdrawal group (HWG), methadone detoxication group (MDG) and heroin relapse group (HRG). Serum was obtained via heart puncture, and the testis was excised soon after heart puncture. Immunohistochemical SABC method, image analysis, and radioimmunoassay were used. Results Compared with NCG and SCG, the mean gray value of EGF-IR cells drawdown in HWG, and revived after the treatment of methadone but still at a high secretion state. In HRG the mean gray value of EGF-IR cells was increased. Compared with NCG and SCG, the mean gray value of CgA-IR cells was declined in HWG, which restored after methadone disposal. In HRG, the immune staining intensity of CgA-IR cells declined. Serum LH levels in HWG and HRG were at a low level, but FSH had no statistically significant in the whole process. Conclusion The testis secretion of EGF,CgA and serum LH level was changed during heroin withdrawal and relapse. The results suggest that the testis secretion of EGF,CgA and serum LH may participate in the process of body adjusting during heroin withdrawal, methadone detoxication and heroin relapse per

Key words: Heroin withdrawal, Heroin relapse, Epidermal growth factor, chromogranin A, Testis, Immunohistochemistry, Radioimmunoassay, Rat