OBJECTIVETo investigate the protective effects of hypothermia combined with dexamethasone on the testis of rats after testicular torsion reduction and on the expression of eNOS and apoptosis of spermatogenic cells.

METHODSWe made unilateral testicular torsion models in 80 adolescent male Sprague-Dawley rats by 720 degrees torsion of the left testis, and then randomly divided them into four groups of equal number to be treated with normal temperature + physiological saline (group A), hypothermia + physiological saline (group B), hypothermia + dexamethasone (group C), and normal temperature + dexamethasone (group D). After 48 hours, we collected the testes, observed pathological changes of the testicular tissue by HE staining under the light microscope, determined the expression of eNOS by immunohistochemistry, and detected the apoptosis of spermatogenic cells by TUNEL.

RESULTSHE staining showed different degrees of testicular tissue injury in all the four groups of rats, most obvious in group A, while protective effect was observed in the other three groups. Immunohistochemistry revealed significantly more positive cells and higher positive staining intensity in the torsion (left) testis in group A than in B (P < 0.05), C (P < 0.01) and D (P < 0.01). The nuclei were deep brown or brown. Lots of apoptotic spermatogenic cells were seen in the torsion testis of group A, with a significantly higher apoptosis index (31.12 +/- 4.68) than in B (16.58 +/- 6.22) (P < 0.05), C (8.60 +/- 1.15) (P < 0.01) and D (13.52 +/- 3.06) (P < 0.01).

CONCLUSIONIschemia-reperfusion injury after testicular torsion reduction can increase the apoptosis of spermatogenic cells and decrease testicular reproductivity. Hypothermia combined with dexamethasone can protect the testis from injury as well as the reproductive function of the testis after testicular torsion reduction.