Riboflavin Recovery of Spermatogenic Dysfunction via a Dual Inhibition of Oxidative Changes and Regulation of the PINK1-Mediated Pathway in Arsenic-Injured Rat Model

Arsenic trioxide (As2O3) poisoning and associated potential lesions are of a global concern. Inversely, riboflavin (vitamin B2) as a component of flavoproteins could play a vital role in the spermatogenic enzymatic reactions. Thus, this research aimed to explore potential beneficial roles of vitamin B2 during As2O3-injured-toxicity. Rats were randomly allocated into 4 groups (n=8/group) and challenged as follows (for 30 days continuously): Group 1 received normal saline, Group 2 was treated with 3 mg/l As2O3, Group 3 received 40 mg/l vitamin B2, Group 4 received 3 mg/l As2O3 + 40 mg/l vitamin B2. Both As2O3 and vitamin B2 were dissolved in deionized water. Malondialdehyde (MDA), Glutathione Peroxidase (GSH-Px), Superoxide dismutase (SOD), and Catalase (CAT) were assessed for the oxidative profile, while TAS (Total Antioxidative Status) levels were evaluated for the antioxidant system, in both serum and testicular tissue. P<0.05 was considered statistically significant. The results show that As2O3 significantly decreased the body weight, testicular weight and testis volume, semen quality and testicular cell count (p<0.05). Furthermore, MDA content in the testicular tissue of the As2O3 group rats was significantly higher in comparison to the vehicle group (p<0.05). Likewise, TAS and the activities of GSH-Px, CAT and SOD were reduced (p<0.05) when compared to the control. As2O3 induced testicular damage and seminiferous tubular atrophy. Monodansylcadaverine assays mirrored the histopathology observations. Meanwhile, As2O3 upregulated the expression of mitophagy-related genes including PINK1, Parkin, USP8, LC3-I, Fis1 and Mfn2. The p38 gene, responsible to stress stimuli, was also upregulated by As2O3 administration. Meanwhile, exposure to Vitamin B2 led to a significant decrease of the expression levels of mitophagy related genes. Our study revealed that vitamin B2 supplementation protected testicular structures against As2O3-induced injury via a dual inhibition of oxidative changes and a regulation of the PINK1-mediated pathway.