Dietary supplementation with Yucca schidigera extract alleviated heat stress-induced unfolded protein response and oxidative stress in the intestine of Nile tilapia (Oreochromis niloticus).

Heat stress due to global warming exerts deleterious effects on both humans and animals. However, nutritional strategies to reduce heat stress-induced intestinal mucosal barrier dysfunction and the underlying mechanisms remain largely unknown. In the present study, 240 tilapia were distributed into four treatment groups that were fed a basal diet supplemented with or without 0.1% Yucca schidigera extract under normal (28 °C) temperature or heat stress (36 °C) conditions for 2 weeks. Our results showed that tilapia exposed to heat stress resulted in growth arrest, intestinal dysfunction, oxidative damage, endoplasmic reticulum stress, and pro-inflammatory response, which were significantly relieved by yucca supplementation. The alleviative effect of Yucca schidigera extract was related to the down-regulation of mRNA expression of ubiquitin-proteasome system (Polyubiquitin, Proteasome 26S, Proteasome α5, Proteasome β3, and Ubiquitin-like 3) and inflammatory factors (tumor necrosis factor α, interleukin 1β, and interleukin 8), as well as the improved histological structure and activation of Hsp70, nuclear factor erythroid 2-related factor 2 signaling, interleukin 10, lysozyme, complement 3, and acid phosphatase in the intestine of tilapia. Collectively, these results indicated that heat stress-induced growth arrest, intestinal dysfunction, and oxidative damage were alleviated by dietary supplementation with Yucca schidigera extract. This offers a nutritional way of improving the growth and intestinal health of tilapia exposed to a hot environment.