Soya-bean agglutinin induced both direct and cholecystokinin-mediated pancreatic enzyme synthesis in rats

Abstract

This study was conducted to examine the relationship between soya-bean agglutinin and cholecystokinin in stimulating pancreatic enzyme synthesis in rats. In experiment 1, 30 rats were given daily gastric infusions of 0, 3·5, 7·0, 10·5, or 14·0 mg of soya-bean agglutinin (no.=6) for 14 days. Compared with the control group, soya-bean agglutinin reduced weight gains, enhanced absolute and relative dry pancreatic weights, elevated serum cholecystokinin levels, and stimulated cholecystokinin mRNA expression in the intestine (P<0·001). Pancreatic nucleic acid composition and the pancreatic activities of the enzymes amylase, trypsin and chymotrypsin all increased in response to increasing levels of soya-bean agglutinin (P<0·001). In experiment 2, duodenal cells obtained from two rats were incubated at 37°C with either saline, 100 μg/ml soya-bean agglutinin, or a mixture of 100 μg/ml soya-bean agglutinin and 10 mmol/m of the L-type, calcium channel antagonist verapamil. Soya-bean agglutinin stimulated cholecystokinin mRNA expression and cholecystokinin release from small intestinal mucosal cells, and the effect was attenuated by verapamil. In experiment 3, pancreatic acinar cells, obtained from three rats, were incubated at 37 °C with either saline, or cholecystokinin (100 fmol/ml) and soya-bean agglutinin (1000 fmol/ml), either alone or in combination. Amylase, trypsin, and chymotrypsin activities from both culture media and acini cells were stimulated by both the soya-bean agglutinin and the cholecystokinin treatments. Enzyme activities, when the two factors were incubated in combination, were intermediate to those obtained when the factors were incubated alone. This suggesting that soya-bean agglutinin may depress the action of cholecystokinin on pancreatic enzymatic activities. In summary, soya-bean agglutinin appears to stimulate pancreatic enzyme synthesis both directly and also through a cholecystokinin-mediated pathway.

Bowman-Birk and Kunitz Protease Inhibitors among Antinutrients and Bioactives Modified by Germination and Hydrolysis in Brazilian Soybean Cultivar BRS 133

“…5 Lectins can bind to intestinal epithelium causing disruption of the brush border membrane and poorer growth of spleen and kidneys. 6 Hence, there is a need to find methods of removing these antinutritional factors, without affecting bioactive compounds, to further increase the acceptance and use of soybean as a part of the animal and human diet.…”

“…For instance, Bowman-Birk trypsin/chymotrypsin and Kunitz trypsin inhibitors (KTIs) can cause an increase in the secretion of digestive enzymes by inducing hypertrophy and hyperplasia of the pancreas and reducing crude protein digestibility in monogastrics; this concept is still controversial in humans . Lectins can bind to intestinal epithelium causing disruption of the brush border membrane and poorer growth of spleen and kidneys . Hence, there is a need to find methods of removing these antinutritional factors, without affecting bioactive compounds, to further increase the acceptance and use of soybean as a part of the animal and human diet.…”

“…Different treatments such as heating, enzymatic hydrolysis, irradiation, use of chelating agents, and germination have been used to eliminate these antinutritional factors. For instance, a combination of heat denaturation and pepsin and pancreatin treatment showed great promise in completely reducing soybean lectin activity, , while γ-irradiation , and electron beam irradiation resulted in reduced trypsin inhibitory activity, lipoxygenase activity, and phytic acid and oligosaccharide contents. Previous studies also showed that germination is an inexpensive and effective technology in reducing the concentration of antinutritional factors while enhancing protein digestibility. − However, to our knowledge, no previous study has shown the effect of combining germination and Alcalase hydrolysis on the concentration of antinutritional and bioactive compounds present in Brazilian soybean cultivar BRS 133.…”