Mandarin fish, Betaine, AMPK/mTOR, Appetite regulation, Glucose-lipid metabolism, Science (General), Q1-390, Social sciences (General), H1-99

Diets with high carbohydrate (HC) was reported to have influence on appetite and intermediary metabolism in fish. To illustrate whether betaine could improve appetite and glucose-lipid metabolism in aquatic animals, mandarin fish (Siniperca chuatsi) were fed with the HC diets with or without betaine for 8 weeks. The results suggested that betaine enhanced feed intake by regulating the hypothalamic appetite genes. The HC diet-induced downregulation of AMPK and appetite genes was also positively correlated with the decreased autophagy genes, suggesting a possible mechanism that AMPK/mTOR signaling might regulate appetite through autophagy. The HC diet remarkably elevated transcriptional levels of genes related to lipogenesis, while betaine alleviated the HC-induced hepatic lipid deposition. Additionally, betaine supplementation tended to store the energy storage as hepatic glycogen. Our findings proposed the possible mechanism for appetite regulation through autophagy via AMPK/mTOR, and demonstrated the feasibility of betaine as an aquafeed additive to regulate appetite and intermediary metabolism in fish.