Alpha-lipoic acid supplementation mitigates heat stress-induced decline in porcine oocyte quality

Heat stress (HS) triggered by elevated summer temperatures has emerged as a critical threat to the reproduction in animal husbandry. Alpha-lipoic acid (ALA), a renowned antioxidant, has been shown to modulate cellular stress responses and maintain energy homeostasis. However, whether ALA can alleviate heat stress-induced decline in porcine oocyte maturation quality remains unclear. In present study we reported that ALA supplementation could rescue porcine oocyte maturation capacity under heat stress condition. We showed that ALA significantly increased the first polar body extrusion rate of oocytes under heat stress, indicating the enhancement of nuclear maturation, which could be confirmed by cytoskeletal integrity, since spindle organization, chromosome alignment and actin filament distribution were protected by ALA treatment. Besides, ALA mitigated heat stress-induced mitochondrial dysfunction by normalizing membrane potential and distribution, and by restraining aberrant DRP1 activation. This further reduced ROS level and positive Annexin-V and alleviated DNA damage signals. We also showed that ALA normalized the expression of proteins related to post-translational modification and intracellular transport. Taken together, our results suggested that ALA alleviated the damage of heat stress on oocyte quality and developmental potential from both nuclear maturation and cytoplasmic maturation, which is a potential heat stress protective agent for animal reproduction.