Effects of dietary sodium acetate on food intake, weight gain, intestinal digestive enzyme activities, energy metabolism and gut microbiota in cultured fish: Zebrafish as a model

Acetate is the most abundant short-chain fatty acids (SCFAs) in the gastrointestinal tract of fish. The aim of this study was to investigate the effects of dietary sodium acetate (NaAc) on food intake, weight gain, intestinal digestive enzyme activities, energy metabolism and gut microbiota of zebrafish (Danio rerio). In this study, 1-month-old zebrafish were fed with 0.15% NaAc diet for 4 weeks under satiation feeding. At the end of feeding trial, the level of intestinal acetate in the fish fed with 0.15% NaAc containing diet were significantly increased (p < .05), which was accompanied by a higher weight gain and daily feeding rate compared with the control group (p < .05). Dietary supplementation of 0.15% NaAc significantly promoted the body fat mass, energy gain and energy conversion efficiency, as well as intestinal digestive enzyme (amylase) activity in fish (p < .05). The expression of food intake-related genes (ghre, npy and npy7R) in the brain of fish fed on the diet contacting 0.15% NaAc was higher than that of the control group. Consistently, intracerebroventricular injection of NaAc in the brain of zebrafish also increased the expression of genes related to food intake. The effects of NaAc on orexigenic genes expression in the brain of zebrafish could be prevented by co-injection of atropine, suggesting that acetate played a direct role in controlling appetite through the parasympathetic nerve system. Moreover, there was significantly decrease (p < .05) in the relative abundance of Plesiomonas genus in the fish gut fed on the diet supplemented with NaAc. These data suggest that NaAc has a potential value as fish feed additive in aquaculture.