OBJECTIVETo observe the apoptosis of spermatogenic cells and the expressions of Bcl-2 and Bax proteins after burying the testis in the inguinal pocket, and to investigate their relationship.

METHODSWe randomly divided 36 healthy male New Zealand white rabbits into an experimental group (n = 18) and a control group (n = 18). Models were established by burying testes in the inguinal pocket in the experimental group, while the controls were left untreated. At the end of the 8th week after surgery, 6 animals were randomly taken from each group for measurement of the testis surface temperature and testicular biopsy. The apoptosis of spermatogenic cells in the testis tissues was detected by TUNEL assay, and the expressions of Bcl-2 and Bax proteins determined by immunohistochemistry and imaging analysis.

RESULTSAt 8 weeks after burying the testis in the inguinal pocket, the testicular surface temperature was significantly higher in the experimental group than in the control ([ 38.02 +/- 0.36] degrees C vs [36.15 +/- 0.64 ] degrees C, P < 0.05), and so was the apoptosis index (AI) of spermatogenic cells ([89.69 +/- 3.76] % vs [7.73 +/- 4.95 ] %, P < 0.05). The expression of the Bax protein in the testis was significantly increased, while that of the Bcl-2 protein remarkably decreased in the experimental group as compared with the control group (P < 0.05). The apoptotic cells were mostly primary spermatocytes and round spermatids.

CONCLUSIONElevated local temperature of the testis buried in the inguinal pocket increases the apoptosis of spermatogenic cells, and the spermatogenic cell apoptosis is highly correlated with the decreased expression of Bcl-2 and increased expression of Bax. The changes in the expressions of Bcl-2 and Bax proteins were a main mechanism behind the temperature elevation-induced apoptosis of spermatogenic cells.