DIFFERING PROLIFERATIVE RESPONSES IN PROXIMAL AND DISTAL COLONS OF GROWING RATS FED FOOD EATEN BY ADENOMA PATIENTS

Animal dietary studies related to human colorectal carcinogenesis are usually based on AIN-76A diet, which is dissimilar to human food in so urce, preparation, and content. Our aim was to examine colonic epithel ial proliferation in rats fed a diet based on the mean daily food inta ke of adenoma patients. Foods were prepared as reported by the adenoma patients and dehydrated; 64 Sprague-Dawley rats were fed either ''hum an adenoma'' or AIN-76A diet and every eight weeks, eight from each gr oup were sacrificed. Both groups gained weight equally, had no colonic histological changes, but during the study showed progressive lengthe ning of colonic crypts (P < 0.01) and decreased proliferation (P < 0.0 5) in distal colons. Compared to controls, rats fed human adenoma diet had significantly longer crypts (P < 0.01) and more labeled cells (P < 0.05) at 32 weeks; overall they had increased proliferation (P < 0.0 1), most significantly in the distal colon. Thus, food eaten by adenom a patients induced hyperproliferative changes in the rat colon during growth and maturity, especially the distal colon, as found in humans a t risk for neoplasia.