Role of the enteric nervous system in the colon of patients with idiopathic megacolon.

BACKGROUND/AIMS: To clarify the physiological significance of the enteric nervous system (ENS) in the colon of patients with idiopathic megacolon (IM), we investigated the enteric nerve responses on lesional and normal bowel segments derived from patients with IM and patients who underwent colon resection for colonic cancers.

METHODOLOGY: Eighteen preparations were taken from the lesional colon of 5 patients with IM (4 men and 1 woman, aged 46-70 yrs, mean age 55.8 yrs); 42 were taken from the normal colon of 14 patients with colonic cancer (10 men and 4 woman, aged 48-68 yrs, mean age 54.2 yrs). A mechanographic technique was used to evaluate in vitro muscle responses to electrical field stimulation (EFS) of the adrenergic and cholinergic nerves before and after treatment with various autonomic nerve blockers.

RESULTS

1) Responses to EFS before blockade of adrenergic and cholinergic nerves. The muscle strips in both normal and IM colon demonstrated relaxation reactions rather than contraction reactions by EFS. The relaxation reaction to EFS in the IM was significantly stronger than that in the normal colon (p=0.0366). 2) Responses to EFS after blockade of the adrenergic and cholinergic nerves. The muscle strips in both normal and IM colon demonstrated relaxation reactions rather than contraction reactions by EFS. The relaxation reaction to EFS in the IM was stronger than that in the normal colon (p=0.0467). 3) Tetrodotoxin abolished the EFS responses in the muscle strips in both normal colon and abnormal colon with IM.

CONCLUSIONS

An increase of NANC inhibitory nerves plays an important role in the impaired motility observed in the colon of patients with IM.