Effects of Soy Protein, its Hydrolysate and Peptide Fraction on Lipid Metabolism and Appetite-Related Hormones in Rats

This study was aimed to investigate whether soy protein hydrolysates had beneficial effects on serum and tissue lipid contents and appetite-related hormones as compared with intact soy protein. Four-week-old male Sprague-Dawley rats were fed AIN-93M diet containing high fat (18% w/w) with low protein (10% w/w). After four weeks, the rats were divided into four groups (n = 8/group) and fed experimental diets with different nitrogen sources and levels, respectively; 10% soy protein isolate (10SPI), 25% soy protein isolate (25SPI), 25% soy protein hydrolysates (25SPH) and 25% soy macro-peptide fractions (25SPP, MW > or = 10,000) for six weeks. Weight gain was significantly higher in 25% nitrogen sources-fed groups than in 10% group (10SPI). In 25SPP, perirenal fat mass and serum total lipid were significantly lower than in other groups. As for appetite-related hormones, serum ghrelin concentration was not shown to be different among groups but leptin concentration was significantly decreased in 25SPP. It can be concluded that soy macro-peptide fractions as compared with intact soy protein may have beneficial effects on reducing fat mass and serum lipid.

Effects of Deer Antler Extract on Serum IGF-I, Bone Growth and Splenocyte Proliferation in Growing Rats

Although it has traditionally known that deer antler and medicinal herbs extract contain some functional components for health promotion, the nutritional significance remains to be elucidated. This study examined the efficacy of deer antler extract (DA) , medicinal herbs extract (MH) and their mixture (DAMH) on serum IGF-I, bone growth with growing rats in vivo and splenocyte proliferation with spleen cells in vitro. Three week-old young female rats (Sprague-Dawley) were divided into 4 groups and then fed basal diet (AIN-93G) or experimental diets containing DA, MH, DAMH, respectively, for 7 weeks. We collected blood, liver, kidney, spleen, femur and tibia from rats. There was no significant difference in weight gain, but food intake increased in DA- and MH-fed groups. There were no signs of liver and kidney damage in the DA, MH and DAMH-fed groups compared to basal diet group. In femur and tibia, wet weights, breaking forces and bone minerals (Ca, Mg and Zn) were significantly higher in the DA-fed group than in the other groups. Serum alkaline phosphatase (ALP) , bone-specific alkaline phosphatase (BALP) activities were significantly lower in the DA, MH, DAMH-fed groups than in basal diet group. Also, serum insulin-like growth factor-I (IGF-I) concentrations were significantly increased in DA-fed group compared to the other groups. Therefore DA was shown to have an activity of bone growth promotion by increasing the IGF-I, a major bone growth factor. The deer antler extract showed an enhanced immune action on the primary cultured-cells from spleen of rats, representing that splenocytes were proliferated by lipopolysaccharide (LPS) , but not by concanavalin A (Con A) . These results indicate that deer antler extract has beneficial effects on bone growth via IGF-I and on splenocyte activation.