Dietary monosodium glutamate affects the growth and feed utilization of Eriocheir sinensis by regulating the appetite related genes expression

This study assessed the impacts of monosodium glutamate (MSG) on the growth performance, feed utilization, feed intake, and appetite regulation of Chinese mitten crab, Eriocheir sinensis . A total of 240 juvenile crabs (9.16 ± 0.21 g) were assigned to six experimental diets supplemented with MSG at 0 %, 0.20 %, 0.39 %, 0.59 %, 0.78 % and 0.98 %. The results demonstrated that 0.59 % MSG supplementation significantly enhanced the weight gain rate (WGR), specific growth rate (SGR), and feed utilization of juvenile E. sinensis by increasing feed intake (FI) ( p < 0.05). Moreover, dietary moderate MSG improved the mid-intestine morphology, such as height of microvillus (HMV), width of microvillus (WMV), and thickness of muscularis (TM). The qRT-PCR analysis demonstrated that the mRNA expression levels of the appetite-stimulating neural signals agouti related protein ( agrp) and ghrelin were increased significantly by dietary moderate MSG ( p < 0.05). Conversely, the mRNA levels of protein kinase B ( akt ), target of rapamycin ( tor ) and 4E-binding protein ( 4e-bp ), as well as appetite-suppressing neural signals pro-opiomelanocortin ( pomc ), corticotropin-releasing factor ( crf ) and peptide yy ( pyy ) were significantly down-regulated ( p < 0.05). The two-slope broken-line regression analysis of SGR in relation to dietary MSG levels suggested that the optimum dietary MSG level for juvenile E. sinensis was 5.6 g/kg. Collectively, MSG may potentially stimulate or suppress the appetite regulation neural signals/hormones, thereby modulating the feeding behavior of E. sinensis . • Dietary 0.59 % monosodium glutamate (MSG) significantly improved the growth performance and feed utilization of E. sinensis. • Dietary MSG enhanced appetite by promoting the orexigenic and suppressing the anorexigenic factors/hormone expressions. • Suppression of Akt/TOR/4E-BP signaling pathway increases feed intake of E. sinensis . • Based on the two-slope broken line regression analysis, the optimal dietary MSG level for juvenile crabs was 5.6 g/kg.