Decreased vasoactive intestinal peptide levels and glutathione depletion in acquired megacolon.

We reported decreased vasoactive intestinal peptide levels in acquired megacolon. The origin of altered neuropeptide levels is unknown, but recent work suggested that tissue antioxidants may function as neuroprotectants. Our hypothesis was that altered levels of inhibitory neurotransmitters in human colon are associated with depletion of the tripeptide thiol, glutathione. Normal colon samples (N = 10; from patients 41-80 years old) and acquired megacolon samples (N = 10; from patients 31-98 years old) were obtained at surgery. Vasoactive intestinal peptide levels were decreased in muscularis externa from acquired megacolon (P = 0.01), while there was a modest increase in NADPH diaphorase activity in muscularis externa from megacolon (P = 0.10). Glutathione in acquired megacolon was detectable in muscularis externa from only five specimens (P < 0.05), but was not significantly different (P > 0.05) in the mucosal-submucosal layer. The results supported the presence of vasoactive intestinal peptide and NADPH diaphorase in distinct subpopulations of nerves in human colon. The results also supported the hypothesis that glutathione functions as a neuroprotectant in a subset of patients with acquired megacolon.