Inhibition of intestinal lipases alleviates the adverse effects caused by high-fat diet in Nile tilapia

Intestinal lipases are fat-digesting enzymes, which play vital roles in lipid absorption in the intestine. To study the regulation of intestinal lipase activity in systemic lipid metabolism in fish, especially in the metabolic diseases caused by high-fat diet (HFD) feeding, we inhibited intestinal lipases in Nile tilapia to investigate the physiological consequences. In the present study, Nile tilapia were firstly fed with HFD (12% fat) for 6 weeks to establish a fatty fish model. Afterwards, Orlistat as a potent intestinal lipase inhibitor was added into the HFD for the following 5-week feeding trial, with two dietary doses (Orlistat16 group, 16 mg/kg body weight; Orlistat32 group, 32 mg/kg body weight). After the trial, both doses of Orlistat treatment significantly reduced intestinal lipase activity, fat absorption, hepatic lipid accumulation, and gene expression of lipogenesis, whereas increased gene expression of lipid catabolism. Moreover, intestinal lipase inhibition increased immune enzyme activities, antioxidant capacity, and gene expression of anti-inflammatory cytokines, whereas lowered gene expression of pro-inflammatory cytokines. Besides, Orlistat could also improve the structure of the intestine and increase expression of intestinal tight-coupling protein. Taken together, intestinal lipase inhibition alleviated the adverse effects caused by HFD in Nile tilapia. Thus, intestinal lipases played key roles in absorbing dietary lipid and could be a promising target in regulating systemic lipid metabolism in fish.