Scrotal heat stress causes sperm chromatin damage and cysteinyl aspartate-spicific proteinases 3 changes in fertile men
To observe changes in semen parameters, sperm DNA integrity, chromatin condensation and cysteinyl aspartate-spicific proteinases (Caspase-3) in adult healthy men after scrotal heat stress (SHS).
The scrotums of 19 healthy male volunteers were exposed to the condition of 40–43 °C SHS belt warming 40 min each day for successive 2 days per week. The course of SHS was continuously 3 months. Routine semen analysis, hypo-osmotic swelling (HOS) test, eosin Y (EY) staining sperm HOS and chromatin dispersion (HOS/SCD) test, HOS and aniline blue (HOS/AB) staining test were carried out before, during and after SHS. The activated Caspase 3 levels of spermatozoa were determined with a microtiter plate reader.
The mean parameters of sperm concentration, motility and normal morphological sperm were significantly decreased in groups with sperm being collected during SHS 1, 2 and 3 months when compared with those in groups of pre-SHS (P < 0.01). Statistically significant differences of sperm DNA fragmentation, normal sperm membrane and vitality, and Caspase-3 activity were observed between the groups of before SHS and after SHS 3 months and the groups of during SHS 1, 2 and 3 months (P < 0.001). Three months the SHS stopped, various parameters recovered to the level before SHS. Abnormal sperm with HOS/AB and HOS/SCD showed a negatively significant correlation with normal sperm by HOS/EY test, and WBC in semen showed a positively significant correlation with Caspase-3 activity. The percentage of abnormal sperm by using the test of HOS/SCD showed a positively significant correlation with that of HOS/AB.
The continuously constant SHS can impact the semen quality, sperm DNA integrity, chromatin condensation and Caspase-3, and the combination of HOS plus AB test may simultaneously determine the integrity of membrane and chromatin condensation at the same spermatozoon.
KeywordsSperm Scrotal heating Sperm chromatin condensation Caspase-3 Aniline blue staining
The authors would like to thank doctor Feng Chen (Shandong Provincial Xintai Family Planning Service Station) and Hua-Qiang Liu (Shandong Provincial Pingyin Family Planning Service Station) for their help in semen processing and their technical assistance.
- 15.Zhang LH, Qiu Y, Wang KH, Wang Q, Tao G, Wang LG. Measurement of sperm DNA fragmentation using bright-field microscopy: comparison between sperm chromatin dispersion test and terminal uridine nick-end labeling assay. Fertil Steril. 2010;94:102732.Google Scholar
- 23.Beyret E, Lin H. Pinpointing the expression of piRNAs and function of the PIWI protein subfamily during spermatogenesis in the mouse. Dev Biol. 2011;14215–26.Google Scholar
- 24.World Health Organisation. Laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 4th ed. New York: Cambridge University Press; 1999.Google Scholar
- 25.World Health Organisation 2010 WHO laboratory manual for the Examination and processing of human semen. 5th ed. WHO Press, Prepublication version. p30–32.Google Scholar
- 26.Sellami A, Chakroun N, Ben Zarrouk S, Sellami H, Kebaili S, Rebai T, et al. Assessment of chromatin maturity in human spermatozoa: useful aniline blue assay for routine diagnosis of male infertility. Adv Urol. 2013;578–631.Google Scholar
- 33.Guo J, Tao SX, Chen M, Shi YQ, Zhang ZQ, Li YC, et al. Heat treatment induces liver receptor homolog-1 expression in monkey and rat Sertoli cells. Endocrinology. 2007;131:1137–48.Google Scholar
- 37.Wettemann RP, Wells ME, Johnson RK. Reproductive characteristics of boars during and after exposure to increased ambient temperature. J Anim Sci. 1979;49:1501–5.Google Scholar
- 47.Wang DH, Hu JR, Wang LY, Hu YJ, Tan FQ, Zhou H, et al. The apoptotic function analysis of p53, Apaf1, Caspase3 and Caspase7 during the spermatogenesis of the Chinese fire-bellied newt Cynops orientalis. PLoS One. 2012;7e39920.Google Scholar