Regulation of the enteric nervous system in the internal anal sphincter in Hirschsprung's disease.

BACKGROUND/AIMS: The cause of impaired motility of the aganglionic internal anal sphincter (IAS) in Hirschsprung's disease (HD) is unknown. To clarify the physiological significance of non-adrenergic non-cholinergic (NANC) excitatory and inhibitory nerves in the IAS of HD, we investigated the enteric nerve responses on lesional and normal IAS in patients with HD and in patients who had undergone rectal amputation for low rectal cancer.

METHODOLOGY: Twelve preparations were taken from the lesional IAS of 7 patients with HD (5 boys and 2 girls aged between 6 months and 1.5 years with a mean age of 8 months). Twenty preparations were taken from the normal IAS of 10 patients with low rectal cancer (6 men and 2 women, aged between 48 and 72 years with a mean age of 54.6 years). A mechanographic technique was used to evaluate in vitro muscle responses to the electrical field stimulation (EFS) of adrenergic and cholinergic nerves before and after treatment with various autonomic nerve blockers.

RESULTS

Cholinergic nerves are mainly involved in the regulation of enteric nerve responses to EFS in the normal IAS. The aganglionic IAS of patients with HD was more strongly innervated by cholinergic nerves than the normal IAS (p < 0.05). NANC excitatory and inhibitory nerves were found to act on the normal IAS, but had no effect on it in aganglionosis.

CONCLUSIONS

These findings suggest that NANC excitatory and inhibitory nerves play an important role in the impaired motility observed in the IAS in HD.