Are there any functional differences of nitric oxide between the transitional segment in Hirschsprung's disease and the diseased colon in hypoganglionosis?

BACKGROUND/AIMS: In histological studies, there are no significant differences between the transitional segment (TS) of Hirschsprung's disease (HD) and the diseased segment in patients with hypoganglionosis (Hypo). In contrast, there are no reports whether or not TS show impaired motility like Hypo. Nitric oxide (NO) has recently been shown to be a neurotransmitter in the non-adrenergic noncholinergic (NANC) inhibitory nerves in the human gut. To clarify the significance of NO in TS and Hypo, enteric nervous responses in colonic tissue obtained from TS and Hypo were investigated.

METHODOLOGY: This study investigated responses of the enteric nervous system including NANC inhibitory nerves in colonic tissue obtained from TS in 10 patients with HD (8 boys and 2 girls, aged from 6 months to 2 years) and diseased colon in 6 patients with Hypo (6 boys, aged from 6 months to 2 years). Normal colons obtained from patients with HD and Hypo (n = 16) were used as controls. Mechanography was used to evaluate in vitro colonic responses to electrical field stimulation (EFS) of adrenergic and cholinergic nerves before and after treatments with various autonomic nerve blockers, N(G)-monomethyl-L-arginine (L-NMMA), and L-arginine.

RESULTS: Non-adrenergic non-cholinergic (NANC) inhibitory nerves were found to act on the normal colon and to a lesser extent both in the TS and Hypo. In addition, there were no significant differences between the TS and Hypo. Nitric oxide (NO) mediates the relaxation reaction of the NANC inhibitory nerve in the normal colon and to a lesser extent both in the TS and Hypo. In addition, there were no significant difference between the TS and Hypo.

CONCLUSIONS: Diminution of NO mediation of NANC inhibitory nerves may be largely related to the impaired motility observed in patients with TS and diseased colon of Hypo.