No abstract

Postweaning stress in mammalian in vivo models leads to significant oxidative stress in the body as well as inducing hormonal disturbance. In this study, we assessed progressive alterations in reactive oxygen species (ROS), which at high levels can show oxidative stress, in addition to oxidative damage to the DNA structure of rabbits. Different groups of rabbits were fasted for 48 h per week for 3 weeks, fed a commercial diet with probiotics added (200 mg of Bacillus licheniformis and Bacillus subtilis), and fasted while being treated with probiotics. The results showed that weaning induced a significant elevation in oxidative stress markers, such as the ROS-related genes malate dehydrogenase 1 (MDH1) and flavin-containing monooxygenase 2 (FMO2), DNA damage, and hormonal disturbance. However, probiotic treatment resulted in significant decreases in the levels of malondialdehyde, cortisol, and triiodothyronine (T3); DNA damage; and apoptosis, as well as changes in the expression of ROS-related genes. On the other hand, supplementation with probiotics reduced these postweaning stress signs in fasted animal models by elevating the genes encoding catalase and superoxide dismutase as well as increasing glutathione peroxidase (GSH-Px), glutathione–s-transferase, alkaline phosphatase, glucose, and thyroxin (T4) levels. The results suggest that supplementation with probiotics accompanied by a fasting program could decrease oxidative stress, ROS genes, and genomic DNA damage and improve the hormonal status that is induced by postweaning stress in mammalian in vivo models.

The current study evaluated the physiochemical quality and gene expression profile of post‐thawed buck semen after supplementation with antioxidants [melatonin (M), L‐carnitine (LC), cysteine (Cys), LC + M, M + Cys, LC + Cys, LC + Cys + M] in comparison with the non‐treated control group. Physical and biochemical characteristics of semen were evaluated following freezing and thawing. Transcript abundance of six selected candidate genes was profile using quantitative real‐time PCR. The data demonstrated significant enhancement of post‐freezing total motility, progressive motility, percentage of live sperm, CASA parameters, plasma membrane and acrosome integrity in all groups supplemented with Cys, LC, M + Cys and LC + Cys compared with the control group. The biochemical analysis of semen indicated that semen groups supplemented with LC and LC + Cys recorded increased levels of GPX and SOD that were coupled with up‐regulation of antioxidant genes (SOD1, GPX1 and NRF2) and mitochondrial transcripts (CPT2 and ATP5F1A). Moreover, H2O2 level and DNA fragmentation percentage were reduced compared with other groups. In conclusion, supplementation of Cys alone or in combination with LC positively improved the post‐thaw physiochemical properties of rabbit semen through activation of bioenergetics‐related mitochondrial genes and cellular antioxidant defence mechanism.