OBJECTIVETo investigate the effects of acute heat stress on the expression patterns of heat shock protein 70 (HSP70) in the testis, epididymis and vas deferens of adult male mice.

METHODSThirty-two 8-week-old male mice were randomly divided into a control and 3 heat stress groups. After a week of pretreatment, the latter 3 groups were exposed to heat stress at (39 +/- 0.5) degrees C for 0.5, 1 and 3 hours, respectively, followed immediately by collection of the blood and determination of glutamic oxaloacetic transaminase (GOT) concentration. Sperm suspension was made from one epididymis for the detection of sperm concentration and abnormal acrosome rate, while the testis, epididymis and vas deferens on the other side were harvested for immunohistochemical analysis.

RESULTSHeat stress induced different degrees of decrease in epididymis indexes and sperm concentration and a dramatic increase in GOT concentration (P < 0.01), but caused no significant changes in the body weight, testis indexes and abnormal acrosome rate in the mice (P > 0.05). There was a tendency of gradual descent in sperm concentration and ascent in abnormal acrosome rate with the increasing time of heat stress. The most decrease in body weight, testis indexes and epididymis indexes was observed in the 0.5 h group. Immunohistochemical results showed that HSP70 was expressed in the testis, epididymis and vas deferens, mildly in the Leydig cells of the testis and distributed in the nuclei of the Leydig cells, spermatoblasts and spermatocytes. In the epididymis, HSP70 was expressed mainly in the cytoplasm of principal and ciliated cells, but not in the basal and clear cells, while in the vas deferens, it was observed mainly in the cytoplasm of the basal cells, but not in the principal cells. With the increase of heating time, the HSP70 expression was markedly elevated in the testis and epididymis, but not so obviously in the vas deferens.

CONCLUSIONAcute heat stress was harmful to the reproductive system of adult male mice. The region- and cell-specific patterns of HSP70 expressions in the testis, epididymis and vas deferens suggested that HSP70 might play an important role in spermatogenesis and sperm maturation. The dramatic increase of HSP70 expression after heat stress might be responsible for the prevention of cells from high temperature.