CHANGES IN SUBSTANCE P-IMMUNOREACTIVE INNERVATION OF HUMAN COLON ASSOCIATED WITH ULCERATIVE-COLITIS

The amount of colonic substance P and substance P-receptors is increas ed in ulcerative colitis, which may denote that substance-P is involve d as a neurogenic mediator in the inflammatory process of ulcerative c olitis. We studied the anatomical distribution of elevated colonic sub stance P in ulcerative colitis and assessed morphometrically whether t he changes in substance P correlate with alterations in colonic innerv ation. Full-thickness specimens of colonic wall were obtained from nor mal human colons (N = 9) and the most and least affected regions of ul cerative colitis colons (N = 10) and immunostained for substance P. Su bstance P immunoreactivity index was calculated by multiplying each in tensity value by the number of pixels exhibiting this intensity value. The numbers of substance P-immunoreactive nerve fibers in the lamina propria were markedly increased, and their fluorescence intensity was enhanced in ulcerative colitis. The longitudinal muscle layer containe d substance P-immunoreactive nerve fibers in ulcerative colitis, but n ot in the controls. The substance P-immunoreactive index (= number x i ntensity of nerve fibers) was 3.42 +/- 1.49 in controls, 21.19 +/- 7.7 9 in mild ulcerative colitis regions (P < 0.05), and 29.68 +/- 9.81 in severe ulcerative colitis regions (P < 0.01). Increase in the number of substance P nerve fibers is in accordance with the hypothesis that substance P contributes to neurogenic mediation of inflammation in ulc erative colitis.