Background: Aluminum, as an environmental pollutant, has destructive effects by inducing oxidative stress on male reproductive system and sperm. Silymarin, an effective substance extracted from Silybum marianum, is a potent antioxidant which inhibits oxidative stress. Because of toxic effects of aluminum and the antioxidant role of silymarin, this study was performed to investigate if silymarin can prevent the adverse effects of aluminum chloride on plasma membrane integrity and acrosome integrity in ram sperm.

Materials and Methods:  In this experimental study, epididymal spermatozoa from Farahani's ram are divided into five groups: sperm at 0 hour, sperm at 180 minutes (control), sperm treated with aluminum chloride (0.5mM) for 180 minutes, sperm treated with silymarin (0.5μM) + aluminum chloride (0.5μM) for 180 minutes and sperm treated with silymarin (0.5μM) for 180 minutes. To evaluate sperm plasma membrane integrity and sperm acrosome integrity, propidium iodide-Hoechst and comassie brilliant blue staining were used, respectively. The results were analyzed using one-way ANOVA and p<0.05 was considered as significant level.

Results:  The percentage of sperm plasma membrane integrity and acrosome integrity were significantly decreased in aluminum chloride group compared to the control. The simultaneous use of silymarin+aluminum chloride could significantly compensate the adverse effects of aluminum chloride on the sperm plasma membrane integrity and acrosome integrity compared to aluminum chloride.

Conclusion: Aluminum chloride induces toxic effect on ram sperm plasma membrane integrity and acrosome integrity and silymarin is able to compensate the adverse effect this pollutant on these parameters.