Fast-twitch muscle hypertrophy partly induces lipid accumulation inhibition with Alaska pollack protein intake in rats

Abstract

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 serum triglyceride and body fat accumulation in rats, the mechanisms underlying these effects are poorly understood. In the present study, we fed 5-week-old male Sprague-Dawley rats a high-fat diet with APP or casein for 4 weeks. We reconfirmed that the intake of APP decreases serum triglycerides and inhibits visceral body fat accumulation in rats. We found that APP had a higher non-digestive protein content than casein, and the amount of protein in feces was higher in the APP group than in the casein group. However, the amount of total lipids in feces did not differ significantly between the groups. We also found that the gastrocnemius muscle, a fast-twitch muscle, tended to increase in weight, and that the epididymal fat weight correlated negatively with gastrocnemius muscle weight in the APP group. These results imply that the enhancement of basal energy expenditure by fast-twitch muscle hypertrophy, rather than the enhancement of lipid excretion via feces, partly causes APP-induced inhibition of lipid accumulation in rats.

Fish protein intake induces fast-muscle hypertrophy and reduces liver lipids and serum glucose levels in rats

“…These results were consistent with those of our previous study in which the rats were fed fish protein for 4 weeks, 1) and the effects of fish protein on skeletal muscle weight were enhanced by extending the fish protein feeding period. Although the muscle hypertrophy was observed with fish protein intake, the precise mechanism was unclear in this study.…”

“…Thus, it is meaningful to modulate muscle fiber type as desired with the use of food. Because fish protein intake induced muscle hypertrophy mainly in the fast muscle fiber type in our previous study, 1) we hypothesized that fish protein intake induces other qualitative changes besides the hypertrophy effect in muscles, such as fiber-type changes. The purpose of the present study was to evaluate the qualitative changes in skeletal muscles with fish protein intake by measuring fiber-type specific gene expression and the expression of genes involved in muscle fat and carbohydrate metabolism.…”

“…Nutritional analyses of casein and fish protein sources were performed at Japan Food Research Laboratories (Tokyo), as in our previous report. 1) At six weeks of age, 20 rats were assigned to one of two experimental groups (n = 10): a high-fat casein diet group, based on the AIN-93 control diet, which is formulated from 200 g/kg of casein, 3 g/kg of cystine, 257 g/kg of α-corn starch, 200 g/kg of sucrose, 30 g/kg of soybean oil, 215 g/kg of lard, 50 g/kg of cellulose, 35 g/kg of AIN-93G mineral mixture, and 10 g/kg of AIN-93 vitamin mixture containing 25 g of choline bitartrate/ 100 g, or another group in which fish protein replaced casein. The amino acid components and nutritional analyses of protein sources in this study are shown in Table 1.…”

“…Recently, we reported the possibility of fish protein enhancing basal energy expenditure by muscle hypertrophy and reducing serum triacylglycerol and body fat accumulation in rats. 1) Since obesity and hypertriglyceridemia are related to coronary heart disease, 2) the increasing skeletal muscle weight with fish protein may be effective in the prevention of coronary heart disease. Furthermore, other researchers have also reported that fish protein decreases visceral fat accumulation, hypercholesterolemia, and hypertriglyceridemia.…”

Alaska Pollack Protein Decreases Brain 3-methoxy-4-hydroxyphenylglycol Levels in Fasting Chicks

“…Alaska pollack protein (APP) enhances basal energy expenditure by fast-twitch muscle hypertrophy and reduces serum triacylglycerol and body fat accumulation in rats (Mizushige et al, 2010). On the other hand, supplementation of fish protein hydrolysate arising mainly from cod and mackerel was reported to attenuate restraint stress-induced plasma norepinephrine (NE) and epinephrine increases in rats (Bernet et al, 2000).…”