REVERSIBLE EFFECT OF PHYTOHEMAGGLUTININ ON THE GROWTH AND METABOLISM OF RAT GASTROINTESTINAL-TRACT

The lectin, phytohaemagglutinin, present in beans survives passage thr ough the gastrointestinal tract in a biologically and immunologically intact form. It is known that by binding to the brush border membranes of the small intestine phytohaemagglutinin induces its hyperplastic g rowth. However, its effect on the other parts of the gut are not known . This study considered the dose and time dependent changes in the gas trointestinal tract exposed to phytohaemagglutinin. Lectin binding was detected by polyclonal antibodies using PAP staining to the surface a nd the parietal cell region of the stomach, the brush border epitheliu m of the small intestine, and to the surface membrane of the caecum an d colon. To characterise the metabolic changes in the gut organ weight s, protein, RNA, DNA, and polyamine contents were measured. While phyt ohaemagglutinin induced a dose and time dependent growth of the small intestine by lengthening the tissue and thickening the gut wall by inc reasing the number of crypt cells, the lectin also changed the size an d metabolism of the large intestine and pancreas, but this growth was by hypertrophy. Phytohaemagglutinin in the diet influences the size, m etabolism, and function of the entire digestive tract. The lectin indu ced changes were fully or partially reversed within three days.