Glutamate and aspartate alleviate testicular/epididymal oxidative stress by supporting antioxidant enzymes and immune defense systems in boars.

Several potential oxidative agents have damaging effects on mammalian reproductive systems. This study was conducted to investigate the effects of glutamate (Glu) and aspartate (Asp) supplementation on antioxidant enzymes and immune defense systems in the outer scrotum of boars injected with H2O2. A total of 24 healthy boars were randomly divided into 4 treatment groups: control (basal diet, saline-treated), H2O2 (basal diet, H2O2-challenged outer scrotum (1 mL kg-1 BW)), Glu (basal diet +2% Glu, H2O2-challenged), and Asp (basal diet+2% Asp, H2O2-challenged). Our results showed that both Glu and Asp supplementation improved testicular morphology and decreased the genital index in the H2O2-treated boars. Glu and Asp administration increased the antioxidant enzyme activities and affected the testicular inflammatory cytokine secretion but had no effect on sex hormone levels. Furthermore, the mRNA expression of CAT, CuZnSOD, and GPx4 was altered in the testes and epididymis of boars treated with Asp and Glu. Glu and Asp supplementation also modulated the expression of TGF-β1, IL-10, TNF-α, IL-6 and IL-1β in the testis and epididymis. These results indicate that dietary Glu and Asp supplementation might enhance antioxidant capacity and regulate the secretion and expression of inflammatory cytokines to protect the testes and epididymis of boars against oxidative stress.