Protective Effect of Silymarin on Cadmium-Induced Apoptosis in Human Sperm

Background: Infertility could be one of tragic realities in industrialareas. Approximately ۴۰-۵۰% of infertility is related tomen. In industrial cities, the incidence of infertility may be dueto environmental pollutants and heavy metals. Cadmium is aheavy metal and environmental pollutant that induces apoptosisin different types of tissues and cells. Cadmium is also able toexert its adverse effects on male reproductive system and spermthrough apoptosis. Several lines of studies suggest that cadmiumcan induce apoptosis in the cells via caspase-dependent andindependent pathways. Apoptosis, programmed cell death, is aform of cell death that occurs in all multicellular organisms forremoving damaged cells. DNA fragmentation, cell shrinkage,the decrease of mitochondrial membrane potential and the activationof caspases are some features of apoptosis. The aim ofthis study was to investigate mechanism by which apoptosis isinduced in human spermatozoa treated with cadmium chlorideand if silymarin, as a potent antioxidant, is able to prevent thetoxic effects of cadmium chloride.Materials and Methods: Human ejaculated spermatozoa weredivided into five groups: ۱. spermatozoa at ۰ hour, ۲. spermatozoaat ۱۸۰ minutes (control), ۳. spermatozoa treated withcadmium chloride (۲۰ μM) for ۱۸۰ minutes, ۴. spermatozoatreated with silymarin (۲ μM) and cadmium chloride (۲۰ μM)for ۱۸۰ minutes, ۵. spermatozoa treated with silymarin (۲ μM)for ۱۸۰ minutes . DNA integrity was performed by sperm chromatindispersion test (SCD). Nucleus diameter was evaluatedby diff-quick staining, whereas flow cytometry was used to assesssperm size. Rhodamine ۱۲۳ staining and the application ofcleaved caspase-۳ antibody were used to study mitochondrialmembrane potential and the activation of caspase-۳, respectively.One-way analysis of variance (ANOVA) followed by theTukey's test was used to assess the statistical significance of thedata and P<۰.۰۵ was considered significant.Results: Cadmium chloride significantly decreased DNA integrity,nucleus diameter, sperm size and mitochondrial membranepotential compared to the control group. Immunocytochemistrystudy showed no intense immunoreactivity against the antibodyin the cadmium chloride group. In the silymarin + cadmiumchloride group, silymarin could compensate the adverse effectsof cadmium chloride on DNA integrity, nucleus diameter andmitochondrial membrane potential.Conclusion: Cadmium chloride exerts apoptosis in humanspermatozoa through a caspase-independent manner and silymarincompensate the toxic effects of cadmium chloride.

کلیدواژه ها:

Human Sperm ، Silymarin ، Cadmium Chloride ، Apoptosis