OBJECTIVETo investigate the effects of experimental left varicocele (ELV) on the expression of sperm associated antigen 11 (SPAG11) mRNA and its protein isomer SPAG11E in the testis and epididymis of adolescent rats, and to explore the mechanism of infertility caused by varicocele.

METHODSThe experimental left varicocele model was established in the adolescent male Sprague-Dawley rats. Two and 4 weeks after the operation, the changes of SPAG11 mRNA and SPAG11E expression in the testis and epididymis were detected using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR).

RESULTSThe expected product of SPAG11 367 bp amplified by RT-PCR was detected only in the epididymis. SPAG11E protein was observed mainly in the acrosomal vesicles and acrosome of round and elongating spermatids of the seminiferous epithelium, in the cytoplasm of Leydig cells, and in the supranuclear region of principle cells and stereocilia of the epididymal epithelium. Imaging and statistical analysis showed that SPAG11 mRNA and SPAG11E protein expressions in the left epididymis of the 2- and 4-week ELV groups presented a remarkable decrease (P < 0.05 or P < 0.01) compared with the right side and the corresponding control group, and the same decreased change in the left epididymis (P < 0.05 or P < 0.01) and an obvious reduction of SPAG11E immunopositive reaction in the right epididymis (P < 0.01) were noted in the 4-week group as compared with the 2-week group. No statistical difference of SPAG11E expression in the bilateral testes was found (P > 0.05) between the ELV group and the control, as well as between the 2- and 4-week ELV groups.

CONCLUSIONSPAG11 is a specific gene expressed in the epididymis. The localization and expression of SPAG11E exhibited a region- and cell-specific pattern in both the testis and epididymis of adolescent rats. The expression levels of both SPAG11 mRNA and SPAG11E protein altered obviously in ELV rats. The results suggest that SPAG11 may not only play an important role in spermatogenesis and sperm maturation, but also be associated with varicocele-induced male infertility or subfertility.