Hypertrophy and hyperplasia of the neonatal rat exocrine pancreas induced by orally administered soybean trypsin inhibitor

Effect of the dietary black gram trypsin inhibitory fraction on the pancreatic activity of male albino mice

The effect of raw black gram and black gram trypsin inhibitory fraction on the pancreatic function of male albino mice has been evaluated. Animals were fed autoclaved black gram (Group I), raw black gram (Group II) and autoclaved black gram incorporated with black gram trypsin inhibitory fraction (Group III). Pancreatic total protease, trypsin and amylase activities were elevated significantly in Group II and III animals. Analyses of intestinal contents showed a constant level of total protease activity in all the groups, along with a significant reduction in trypsin level in Groups II and III. Increased U-14C-lysine incorporation in pancreas and an enhanced level of amylase in intestinal contents show the hyperactivity of the pancreas in Groups II and III. Pancreas weights increased in Groups II and III. Pancreatic protein/mg pancreas and RNA/DNA ratio remained constant in all three groups. It is concluded with histological studies that the black gram trypsin inhibitor increased the pancreatic activity of mice by developing the cellular hyperplasia of the pancreas.

Effect of dietary green gram trypsin inhibitor and raw green gram meal (Phaseolus aureus Roxb) on the pancreatic activity in rats

To evaluate the effect of green gram trypsin inhibitor (GGTI) and raw green gram meal (RGG) the experimental animals were fed with the following diets: (i) AGG meal-control (autoclaved green gram meal), (ii) RGG meal and (iii) AGG meal + 1% GGTI. Pancreatic enlargement was observed in rats fed RGG diet and AGG + GGTI diet. Elevated levels of protease and amylase were observed in pancreas. Intestinal contents showed no significant variation in the protease activity, but a significant variation in the amylase activity was evident. Total RNA, DNA and protein content were increased in the pancreas of group II and group III set of animals, suggesting an active proliferation of acinar cells. RNA and DNA content per unit weight of pancreas and the RNA/DNA ratio remained almost constant indicating the hyperplasia. Histological studies revealed hyperplasia of the acinar cells. The results obtained have been discussed.

The effect of long-term feeding of soya-bean flour diets on pancreatic growth in the rat

1. Pancreatic growth was measured in rats by changes in pancreatic weight, nucleic acid content and protein content after feeding diets of heated soya-bean flour (HSF), raw soya-bean flour (RSF), 200 g raw soya-bean flour + 800 g heated soya-bean flour/kg (80 HSF) and 400 g raw soya-bean flour + 600 g heated soya-bean flour/kg (60 HSF) for periods up to 36 weeks. Control rats of comparable age to soya-bean flour-fed rats were continued on rat cubes during the 36-week study. 2. Cube-fed rats remained significantly heavier than rats fed on soya-bean flour diets. Analysis of variance showed rats fed on HSF were significantly heavier than RSF-fed rats and rats fed on 80 HSF significantly heavier than those fed on 60 RSF. 3. Pancreatic indices in HSF-fed rats were similar to comparable control rats. 4. Hypertrophy was found in rats fed on the RSF-containing diets with the extent of enlargement corresponding to the RSH content. Hyperplasia was also found in rats fed on RSF and 60 HSF. 5. The greatest pancreatic growth was seen in RSF-fed rats with all the indices peaking at 8 weeks followed by a decline and then a rise again at 36 weeks. 6. The fall in pancreatic indices in rats fed on RSF for 12 and 24 weeks is most likely an effect of general malnutrition due to the multiple deficiences in amino acids which occur in animals fed on RSF. The rise at 36 weeks may reflect increased body growth or the beginning of adenomatous changes.

Effects of proteolytic enzymes on vitamin B12 uptake by rat intestinal mucosa homogenates and of proteolytic enzymes and anti-rat intrinsic factor antibodies on vitamin B12 absorption in total gastrectomized rats

Trypsin inhibited 57CoB12-rat IF uptake by rat small intestinal mucosa homogenates in vitro. This tryptic inhibition was inactivated by rat serum and normal human serum, as well as soybean trypsin inhibitor (STI). The effects of trypsin dissolved in distilled water or 0.0025 N HCl, 0.15 M saline extract of rat pancreas and STI on vitamin B12 absorption were studied in vivo, using gastrectomized rats. IF-mediated B12 absorption was significantly decreased by 5 mg of trypsin dissolved either in distilled water or 0.0025 N HCl. However, the inhibition of trypsin was much more remarkable when it was dissolved in 0.0025 N HCl, whereas B12 absorption was insignificantly decreased by administering 10 mg of trypsin dissolved in 0.0025 N HCl. The possibilities of this phenomenon was discussed. The inhibitory effect of 0.5 ml of 0.15 M saline extract of rat pancreas was investigated as well. Soybean trypsin inhibition showed no effect on B12 absorption when it was given with 57CoB12-rat IF at the same time. However, the B12 absorption was significantly increased when STI was given one hour prior to the administration of 57CoB12-rat IF. This suggested that endogenous trypsin bound to rat small intestine had been inactivated and pancreatic secretion had been stimulated by STI. IF-mediated B12 absorption was diminished to almost the same level of 57CoB12 administration alone by simultaneous intubation of both 57CoB12-rat IF and rabbit anti-rat IF serum in total gastrectomized rats.

Kinetics of native and modified Bowman-Birk soya-bean trypsin inhibitor on growth and enzymes activities of the chick pancreas

1. The Bowman-Birk soya-bean trypsin inhibitor (BBTI) begins to cause pancreatic enlargement and increased enzymic activity in the pancreas of chicks after a minimum of 7 d of feeding. 2. The active inhibitory site of BBTI against trypsin is the factor involved in the pancreatic enlargement and increase of pancreatic enzyme activity in chicks.

Changes in rat pancreatic protein synthesis after a single feeding with diets containing raw or heated soybeans

The patterns of protein synthesis following the administration of a single meal containing defatted ground soybeans (RSD) or heated defatted ground soybeans (HSD) were compared. A double label method was used so that the determination of the relative rate of synthesis of an enzyme could not be obscured by a possible alteration of the activity or quantity of the enzyme. Rats were given one meal of RSD or HSD and were subsequently killed at different times after the meal. Eight hours after the meal, the relative rate of synthesis of one of the three trypsinogens was substantially increased with RSD feeding, whereas that of the amylases and one chymotrypsinogen were somewhat lower. The synthetic rate of lipase, ribonclease, proelastase, another chymotrypsinogen and of two trypsinogens was unaffected when feeding RSD is compared to feeding HSD. The relative rate of synthesis of one of the trypsinogens was unaffected 8 hours after RSD feeding, but was increased 16 hours after RSD feeding. Actinomycin D could suppress the effects of RSD feeding on the protein synthetic rate of some, but not of all, secretory proteins.

Immunocytochemical study of the interaction of soybean trypsin inhibitor with rat intestinal mucosa

To investigate further the cause of the pancreatic enlargment induced by orally ingested soybean trypsin inhibitor (STI), antibodies raised against STI and purified by affinity chromatography were used to localise dietary STI in the rat gut by fluorescent immunocytochemical methods. This technique permitted the clear intracellular demonstration of STI in the ileal mucosa of suckling rats. However, in adult rats no entry of STI into mucosal cells of the small intestine could be demonstrated, it being confined to the luminal surface of the mucosa. Although the passage of STI into and across the adult intestinal mucosa could not be excluded through the use of this technique, the results are consistent with an intraluminal mode of action of STI as suggested by Green and Lyman (1972)--namely, that the pancreatic enlargement caused in sensitive species results from the inhibition of trypsin (which acts as the physiological inhibitor of the mucosal secretion of pancreotrophic hormones), thus resulting in the uninhibited secretion of these hormones.

Changes in pancreatic and intestinal enzyme activities following chenodeoxycholic acid feeding

The effect of CDCA feeding on pancreatic and intestinal enzymes was studied. Mice were fed 0.5% w/w chenodeoxycholic acid in a normal diet. Pancreatic lipase concentration was significantly increased after 3 days on the CDCA diet, while amylase and trypsin concentrations were significantly higher at 23 days when compared with the controls. At 70 days there was a significant increase in the concentrations of amylase, trypsin, and lipase. Protein concentrations paralleled the rise in enzyme levels. Amylase and lipase, when measured as specific activities, were still higher than the controls at 70 days. Intestinal amylase levels did not change during the experiments, but intestinal alpha-glucosidase activity increased significantly in the CDCA-treated animals. The results are discussed in terms of their similarity with those reported to occur after feeding soybean trypsin inhibitor.