Effects of dietary rice bran trypsin inhibitor on the growth and pancreatic weights of rats

Abstract

Male weanling rats were fed a 11.5% casein basal diet or the casein diets containing rice brain trypsin inhibitor (RBTI) at levels of 1.0, 2.0, and 4.0 g/kg diet for 3 weeks, and the response of rats to dietary RBTI was examined. Results showed that the body weight gain and food efficiency of the 0.4% RBTI diet group were significantly lower than those of the basal diet group at 1 wk, but these differences disappeared at 2 wk. Apparent nitrogen digestibility was also lower in the 0.4% RBTI diet group than in the basal when measured on days 3 and 4 after the start of the trial. Concerning pancreas, a significant increase in the weight was observed in rats given diets containing 0.2% and 0.4% RBTI as compared to rats fed the basal diet, and the levels of trypsin and chymotrypsin activities tended to be higher in the RBTI diet groups than in the basal. These findings indicate that RBTI consumption in weanling rats elicits physiological responses such as growth retardation and pancreatic enlargement. However, the deleterious effects of dietary RBTI seem to be ignored when the ingested level of RBTI is low under the conditions used in this study.