Correlation of neomycin, faecal neutral and acid sterols with colon carcinogenesis in rats

Abstract

Summary High fat diets have been implicated in incidence of colon cancer both in epidemiological and animal studies. Present investigation deals with the incidence, location and numbers of large and small bowel tumours induced by 1,2-dimethyl hydrazine (DMH) in rats fed high fat diets and neomycin. Neomycin was used to modify the faecal sterol metabolism and the relationship of the high fat diet and faecal neutral and acid sterols to the large bowel tumorigenesis was evaluated. DMH administered rats were fed with (a) 20% safflower oil; (b) 20% safflower oil and neomycin; (c) 20% safflower oil, cholesterol and cholic acid; and (d) 20% safflower oil, cholesterol, cholic acid and neomycin. Neomycin was found to be associated with both increase and decrease of tumour numbers. The faecal sterols lithocholic and deoxycholic acids were found to have no participation, while cholesterol and cholic acid were found to decrease with increase in tumour numbers. However, faecal coprostanol has been found to have a significant positive correlation with tumorigenesis in all dietary groups. Therefore coprostanol might possibly be associated with colon carcinogenesis in DMH-fed rats and cholesterol metabolism in gut appears to be related to the development of tumours.

Effect of daily intake of pomegranate juice on fecal microbiota and feces metabolites from healthy volunteers

“…In this sense, it has been established that secondary metabolites of fecal steroids produced by the gut microbiota may promote health or favor disease development depending on the quantity and type produced. Specifically, increased concentrations of secondary bile acids (BAs) and cholesterol microbial metabolites in feces are involved in colorectal carcinogenesis .…”

Correlation between faecal microbial community structure and cholesterol-to-coprostanol conversion in the human gut

“…Whereas unmetabolised cholesterol is subjected to extensive enterohepatic circulation, coprostanol is poorly absorbable and excreted in the faeces [4]. However, epidemiological 0378 studies have revealed that high-risk populations for colon cancer have an increased number of total anaerobes and enhanced metabolism of neutral sterols [7], and coprostanol is thought to be associated with colorectal carcinogenesis [8,9]. However, epidemiological 0378 studies have revealed that high-risk populations for colon cancer have an increased number of total anaerobes and enhanced metabolism of neutral sterols [7], and coprostanol is thought to be associated with colorectal carcinogenesis [8,9].…”

Gnotobiotic rats harboring human intestinal microbiota as a model for studying cholesterol-to-coprostanol conversion

“…The end‐product is mainly the fully saturated and poorly absorbable coprostanol (5β‐cholestan‐3β‐ol) whose formation would facilitate the elimination of cholesterol from the body [1,2], and would therefore decrease the risk of cardiovascular diseases [2]. The ambiguity of coprostanol in a clinical perspective must however be pointed out, since this metabolite could be associated with colorectal carcinogenesis [3–5]. Interestingly, the efficiency of microbial conversion of cholesterol to coprostanol among human populations has been found to be bimodal, with a vast majority of high transformers and a minority of low‐to‐inefficient transformers [6,7].…”