Immunohistochemical study of 3-mercaptopyruvate sulfurtransferase in the digestive system of the lesser bamboo rat (Cannomys badius) in relation to cyanide detoxification

Abstract

The lesser bamboo rat (Cannomys badius), a fossorial rodent distributed in Indochina, has the ability to feed on cyanogenic plants that normally induce cyanide poisoning and lead to cell death. Immunohistochemical staining was used for localizing 3-mercaptopyruvate sulfurtransferase (MST), a cyanide-detoxifying enzyme, in the digestive organs of C. badius. The results revealed MST-positive staining in gastric parietal cells, columnar epithelial cells in the large intestine, hepatocytes, and some endocrine cells in the pancreatic islets. Specifically, cecal and colonic epithelial cells and pericentral hepatocytes were relatively strongly stained. The present study suggests that MST in the parietal cells and the endocrine pancreas is not involved in cyanide detoxification but in the regulation of acid and hormone secretion. It is also postulated that cyanide produced by microbial fermentation of food in the cecum is primarily detoxified by MST in cecal epithelial cells and subsequently neutralized further by MST in the colon and liver. The digestive system of C. badius reflects a protective mechanism against cyanide toxicity allowing it to survive a diet of cyanogenic plants.

Keywords

• epithelial distribution
• gastrointestinal tract
• immunohistochemistry
• rodent