ABSTRACT
PURPOSE: It has been reported that exposure of the testes to elevated temperatures results in decreased spermatogenesis. The aim of this study was to investigate the effects of temperature change on the expression of heat shock protein 70 (HSP 70) during spermatogenesis in rat testes. MATERIALS AND METHODS: Twenty-seven Sprague-Dawley rats (200-230g) were randomly divided into control, hot bath and hot bath followed by cold bath, groups. The hot bath consisted of immersion in a 41-43 degrees C water bath for 10 minutes, and the cold bath consisted of immersion in a 18-20 degrees C water bath for 3 minutes. Each bathing was performed twice a day, three times a week, for a total of four weeks. Hematoxylin & Eosin staining was performed to evaluate the degree of spermatogenesis, and Western blot & immunohistochemistry were performed to investigate the expression of HSP 70 in the rat testes. RESULTS: From the histological tests, the spermatogenesis was severely impaired in hot bath group, but preserved in hot bath followed by cold bath group. The expression of HSP 70 in the hot bath group increased 1.5 times compared to that in the control group (p=0.075). However, the hot followed by cold bath group showed similar findings to those in the controls (p=0.934). Immunohistochemical analysis for the expression of HSP 70 demonstrated significant elevations in the hot bath group, and HSP 70 immunoreactivity was found in the Leydig cells and fibroblasts in all three groups, but the levels of expression of the HSP 70 in the control, and the hot followed by cold bath, groups were similar. CONCLUSIONS: The results of this study demonstrate an elevation in the expression of the HSP 70 only occurred in the hot bath group, which suggests the induction of a coping mechanism for exposure to high temperature. As the levels of expression of the HSP 70 in the control, and hot followed by cold bath, groups were comparable, is suggestive of the levels of HSP 70 being consistent with those seen with normal spermatogenesis.