Fish protein hydrolysate exhibits anti-obesity activity and reduces hypothalamic neuropeptide Y and agouti-related protein mRNA expressions in rats

: Fish protein is a source of animal protein that is consumed worldwide. Although it has been reported that the intake of Alaska pollack protein (APP) reduces body fat accumulation and increases muscle weight in rats, the mechanisms underlying these effects are poorly understood. As a possibility, peptides released from APP in the gastrointestinal tract are important to the functions of APP. In the present study, we examined the effects of APP hydrolysate digested artificially with pepsin and pancreatin on white adipose tissue and skeletal muscle. We found that APP hydrolysate group shows significantly lower weight of white adipose tissue and higher weight of soleus muscle than the control group. We also found that APP hydrolysate group reduces food intake and mRNA expressions of neuropeptide Y and agouti-related protein in the hypothalamus compared with the control group. These results may imply that APP hydrolysate exhibits anti-obesity activity by the reduction of appetite and the enhancement of basal energy expenditure by skeletal muscle hypertrophy in rats. The downregulation of orexigenic gene by APP hydrolysate in the hypothalamus may contribute to the reduction of appetite. These results suggest that the effect of APP on anti-obesity and muscle hypertrophy may be induced by peptides released from APP in the gastrointestinal tract.