OBJECTIVETo investigate the effect of diet-induced obesity on the apoptosis of testicular spermatogenic cells in pubertal male rats.

METHODSForty healthy male rats were equally and randomly divided into a control and a high-fat group, the former fed on normal diet, while the latter high-fat and high-calorie diet. The testes of the rats were harvested at the end of 10 weeks for detection of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in the peripheral blood with the automatic biochemical analyzer. Pathological changes of the testis were observed under the light microscope, the apoptosis of the testicular cells detected by TUNEL, the expressions of Bcl-2 and Bax proteins determined by immunohistochemistry, and those of Bcl-2 mRNA and Bax mRNA measured by RT-PCR.

RESULTSThe levels of TC, TG, LDL-C and HDL-C were significantly higher in the high-fat group (5.17 +/- 0.17, 1.18 +/- 0.09, 1.76 +/- 0.11 and 5.08 +/- 0.18) than in the control (1.38 +/- 0.12, 0.39 +/- 0.05, 0.97 +/- 0.07 and 0.75 +/- 0.06) (P < 0.05), so was the apoptotic index of spermatogenic cells (37.17 +/- 2.74 versus 5.16 +/- 0.81, P < 0.01), and the apoptotic spermatogenic cells were mainly spermatogonia and spermatocytes. The expressions of Bax protein and Bax mRNA were markedly higher in the high-fat group (153.26 +/- 8.74 and 1.08 +/- 0.12) than in the control (101.81 +/- 6.14 and 0.37 +/- 0.04) (P < 0.01), while those of Bcl-2 protein and Bcl-2 mRNA remarkably lower in the former (139.26 +/- 7.21 and 0.46 +/- 0.05) than in the latter (159.37 +/- 8.96 and 1.05 +/- 0.11) (P < 0.01).

CONCLUSIONDiet-induced obesity can increase the apoptosis of spermatogenic cells in the rat testis, which may be associated with the reduced expression of Bcl-2 and elevated expression of Bax.