Dietary selenium mitigates cadmium-induced apoptosis and inflammation in chicken testicles by inhibiting oxidative stress through the activation of the Nrf2/HO-1 signaling pathway

Cadmium (Cd) is a non-essential heavy metal that is highly toxic to testicle. Selenium (Se) is known to possess antagonistic effects against Cd toxicity, yet the precise mechanisms through which Se counteracts Cd-induced testicular damage in chickens through Nuclear factor erythroid 2-related factor 2/Heme oxygenase-1 (Nrf2/HO-1) signaling pathway, oxidative stress (OS), apoptosis, and inflammation remained unclear. In the present study, the experimental model of chicken testis was established by incorporating CdCl₂ and Na₂SeO₃ into the dietary intake. After 60 days, chickens from each group were euthanized, and testicular and serum samples were subsequently collected. Ultrastructural assessment revealed that Se supplementation significantly mitigated the testicular damage induced by Cd. Se effectively suppressed the Cd-induced elevation in ROS, MDA, and H₂O₂ levels, while also preventing the downregulation of CAT, GSH, and T-AOC levels. Furthermore, Se administration ameliorated the reduction in the expression levels of Nrf2, HO-1, and Bcl-2 induced by Cd, and counteracted the overexpression of Caspase-3, Bax, Cyt-c, and Caspase-9, TNF-α, IL-2, IL-6, and IL-1β. Meanwhile, immunofluorescence data demonstrated that Se attenuated the Cd-induced decrease in Nrf2 and HO-1 expression and the upregulation of IL-6 expression. In conclusion, this study elucidated that Se might mitigate Cd-induced oxidative stress in chicken testicles through the stimulation of the Nrf2/HO-1 signaling pathway, thereby inhibiting apoptosis and inflammation, and was beneficial in reducing Cd-induced testicular injury.