Effect of silymarin and metformin on the sperm parameters and histopathological changes of testes in diabetic rats: An experimental study

Background: Oxidative stress is a major contributor to diabetes, which can lead to testicular damage and infertility.
Objective: This study aimed to compare the effects of metformin as a chemical drug with silymarin as an herbal agent on the sperm parameters and histopathological changes of testes in diabetic rats.
Materials and Methods: Thirty-two male Wistar rats (250-270 gr) were randomly divided into four groups: 1) control; 2) diabetic; 3) diabetic+metformin 200 mg/kg; and 4) diabetic+silymarin 100 mg/kg. Daily injections were administered intraperitoneally for 56 days. At the end of the treatment, blood sampling was performed for biochemical assessment. Then, the rats were sacrificed and their left testis and epididymis were cut for sperm analysis as well as histopathology and morphometric evaluation.
Results: Diabetes was associated with a reduced sperm count, motility, viability, maturity, and chromatin quality of sperm (p ≤ 0.001). It was also associated with a higher malondialdehide level and lower total antioxidant capacity level of serum in comparison with the control group (p ≤ 0.001). There was a significant difference in the seminiferous tubule diameter, germinal epithelium height, and testicular histopathological alterations in the diabetic rats compared with the control rats (p ≤ 0.001). Treatment with metformin and silymarin improved the above-mentioned parameters and this improvement was more substantial in silymarin-treated animals (p ≤ 0.001).
Conclusion: In diabetic rats, metformin and silymarin improved sperm parameters, sperm DNA integrity, seminiferous tubule diameter, germinal epithelium thickness, and testicular histopathological complications; this improvement was more substantial in the silymarin-treated group. So, the findings of this study suggest that silymarin is more effective than metformin in treating diabetic-induced infertility.