Methotrexate (MTX) is frequently used in the treatment of several diseases including cancers, rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, and dermatomyositis. Previously, chemotherapeutic agents have been reported to cause permanent azoospermia and infertility in men. Methotrexate has been also shown to damage the seminiferous tubules of the testicles, lower the sperm count, and cause genetic mutations (in DNA) in sperm. In this study, we aimed to investigate the protective effects of alpha lipoic acid (ALA) on MTX-induced testicle damage in a rat model.

A total of 40 male Wistar Albino rats were used in this study. The rats were divided into four groups including 10 rats in each. The first group (control group) received only saline intraperitoneal (i.p.); the second group (ALA group) was given ALA 100 mg/kg i.p.; the third group (MTX group) received single dose MTX 20 mg/kg i.p.; and the fourth group (MTX + ALA group) received single dose MTX 20 mg/kg i.p. and ALA 100 mg/kg i.p. Malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), myeloperoxidase (MPO) levels in the testicular tissue and serum testosterone, serum total antioxidant status (TAS) and total oxidant status (TOS) levels were biochemically evaluated. Testicular tissues histopathologically evaluated.

In the MTX group, the MDA, TAS and TOS levels were higher, while the SOD, CAT, GPx, MPO and serum testosterone levels decreased. Compared to the MTX group, the MDA, TAS and TOS levels were lower and the SOD, CAT, GPx, MPO and serum testosterone levels increased in the MTX + ALA group. In the histopathological examination, the mean seminiferous tubule length (MSTD), germinal epithelial cell thickness (GECT), and mean testicular biopsy score (MTBS) were found to significantly decrease in the MTX group, compared to the control group. These values were significantly higher in the MTX + ALA group, compared to the MTX group (p < 0.05).

In our experimental study, MTX caused severe tissue destruction in testicles by increasing the formation of free oxygen radicals. Based on our study results, we suggest that, as a potent free radical scavenger, ALA can reduce MTX-induced testicular tissue damage thanks to its antioxidant and anti-inflammatory properties.