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Effects of high-fat diet on muscle textural properties, antioxidant status and autophagy of Chinese soft-shelled turtle (Pelodiscus sinensis)

Li, Hong-hui, Pan, Ya-xiong, Liu, Li, Li, Yu-long, Huang, Xue-qing, Zhong, Yi-wen, Tang, Tao, Zhang, Jian-she, Chu, Wu-ying, Shen, Yu-dong
Aquaculture 2019 pp. 734228
Pelodiscus sinensis, adhesion, antioxidant enzymes, antioxidant genes, ash content, autophagy, body weight, catalase, chewiness, cohesion, crude protein, dietary fat, enzyme activity, feed conversion, gene expression, gene expression regulation, glutathione, glutathione peroxidase, glutathione transferase, glutathione-disulfide reductase, hardness, hepatosomatic index, high fat diet, juveniles, lipid content, lipids, malondialdehyde, mechanical properties, muscle tissues, muscles, oxidation, oxidative stress, reactive oxygen species, signal transduction, specific growth rate, superoxide dismutase, survival rate, texture, transmission electron microscopy, turtles, weight gain
This research illustrates the effects of high-fat diet induced oxidative stress on muscle textural properties, oxidation status and autophagy of juvenile Chinese soft-shelled turtles (Pelodiscus sinensis) and explores the molecular regulatory mechanism. A total of 120 juvenile Chinese soft-shelled turtles with the average initial body weight of (38.60 ± 1.13) g were fed two diets that contained different lipid levels, 6.38% (normal diet, ND) and 13.89% (high-fat diet, HFD), for 8 weeks. The results indicated that: (1) the survival rate (SR) and feed conversion rate (FCR) were not significantly different (P > .05); the final body weight, weight gain rate (WGR), specific growth rate (SGR), and the hepatosomatic index (HIS) of groups that were fed with HFD were significantly higher than those fed with ND (P < .05). Moreover, the moisture and ash contents in the muscle and calipash were not significantly affected by the lipid level (P > .05), while the crude lipid content of the turtles increased, and the crude protein content decreased when the dietary lipid concentration increased (P < .05); (2) regarding the textural mechanical properties, no significant differences were observed in adhesiveness, cohesiveness and springiness (P > .05), but a significant decreases in hardness, gumminess and chewiness of muscle with HFD (P < .05); (3) the reactive oxygen species (ROS) and malondialdehyde (MDA) contents were increased in the HFD group (P < .05). It was significantly up-regulated the mRNA level of the signaling molecule Keap1 as well as down-regulated Nrf2 in the muscle (P < .05), meanwhile its downstream the activities of antioxidant enzymes of total superoxide dismutase (T-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GR) and the content of glutathione (GSH) and antioxidant gene expression were significantly decreased (P < .05); (4) the expressions of autophagy-related genes MAP1LC3A, MAP1LC3B, MAP1LC3C and ULK1 were significantly increased in the HFD group, while mTOR was significantly decreased as well as increased AMPK mRNA level (P < .05), and the transmission electron microscopy result showed that there were obviously more autophagosomes in muscle tissues of the HFD group than ND group. In summary, high-fat diet induced oxidative stress and autophagy in the juvenile Chinese soft-shelled turtles, which might be related to increased lipid content and ROS level by down-regulating the mRNA level of antioxidant enzymes, and inhibiting the Nrf2 and mTOR signaling pathways.