nitroarginine and Hirschsprung-Disease

Mutations in genes encoding members of the GDNF and endothelin-3 (Et-3) signaling pathways can cause Hirschsprung's disease, a congenital condition associated with an absence of enteric neurons in the distal gut. GDNF signals through Ret, a receptor tyrosine kinase, and Et-3 signals through endothelin receptor B (Ednrb). The effects of Gdnf, Ret, and ET-3 haploinsufficiency and a null mutation in ET-3 on spontaneous motility patterns in adult and developing mice were investigated. Video recordings were used to construct spatiotemporal maps of spontaneous contractile patterns in colon from postnatal and adult mice in vitro. In Ret(+/-) and ET-3(+/-) mice, which have normal numbers of enteric neurons, colonic migrating motor complexes (CMMCs) displayed similar properties under control conditions and following inhibition of nitric oxide synthase (NOS) activity to wild-type mice. In the colon of Gdnf(+/-) mice and in the ganglionic region of ET-3(-/-) mice, there was a 50-60% reduction in myenteric neuron number. In Gdnf(+/-) mice, CMMCs were present, but abnormal, and the proportion of myenteric neurons containing NOS was not different from that of wild-type mice. In the ganglionic region of postnatal ET-3(-/-) mice, CMMCs were absent, and the proportion of myenteric neurons containing NOS was over 100% higher than in wild-type mice. Thus impairments in spontaneous motility patterns in the colon of Gdnf(+/-) mice and in the ganglionic region of ET-3(-/-) mice are correlated with a reduction in myenteric neuron density.

Topics: Age Factors; Aging; Animals; Animals, Newborn; Colon; Disease Models, Animal; Endothelin-3; Enteric Nervous System; Enzyme Inhibitors; Gastrointestinal Motility; Glial Cell Line-Derived Neurotrophic Factor; Granisetron; Hirschsprung Disease; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Myoelectric Complex, Migrating; Nitric Oxide Synthase; Nitroarginine; Proto-Oncogene Proteins c-ret; Receptors, Serotonin, 5-HT3; Serotonin 5-HT3 Receptor Antagonists; Serotonin Antagonists; Time Factors; Video Recording

It is not clear what contribution the internal anal sphincter (IAS) makes to the impaired motility observed in patients with Hirschsprung's disease (HD). Nitric oxide (NO) has recently been shown to be a neurotransmitter in the nonadrenergic noncholinergic (NANC) inhibitory nerves in the human gut. To clarify the physiologic significance of NO in the IAS of HD (aganglionosis), we investigated the enteric nerve responses on lesional (aganglionic) and normal IAS muscle strips above the dentate line. Lesional and normal IAS muscle strips above the dentate line were derived from patients with HD (10 cases) and patients who underwent rectal amputation for low rectal cancer (12 cases). A mechanographic technique was used to evaluate in vitro muscle responses to electrical field stimulation (EFS) before and after treatment with various autonomic nerve blockers, N(G)-L-nitroarginine, and L-arginine. The following results were obtained: (1) Cholinergic nerves are mainly involved in the regulation of enteric nerve responses to EFS in the normal IAS. (2) The aganglionic IAS of patients with HD was more strongly innervated by cholinergic nerves than the normal IAS (p < 0.05). (3) NANC inhibitory nerves were found to act on the normal IAS but had no effect on the enteric nerves in patients with aganglionosis. (4) NO was found to act on normal IAS, but no effect was observed in the aganglionic IAS. These findings suggest that innervation of the cholinergic nerves and a loss of NO mediation of NANC inhibitory nerves play an important role in the impaired motility observed in the IAS with HD.

Topics: Anal Canal; Arginine; Biopsy, Needle; Case-Control Studies; Child, Preschool; Culture Techniques; Electric Stimulation; Female; Ganglia, Autonomic; Hirschsprung Disease; Humans; Infant; Male; Muscle Contraction; Muscle Relaxation; Neurotransmitter Agents; Nitric Oxide; Nitroarginine; Probability; Reference Values; Sensitivity and Specificity

The pathogenesis of Hirschsprung's disease is not well understood. The suitability of the animal model for the unknown pathogenesis of inhibitory neurotransmission in Hirschsprung's disease was investigated.. Circular smooth muscle strips from the internal anal sphincter (IAS) and distal colon (2, 6, 8, 16, and 24 mm from the anal verge) from normal and Ls/Ls mice (mice homozygous for the lethal spotting mutation that develop fetal megacolon after aganglionosis of the terminal colon) were prepared to record changes in isometric tensions in response to different agents and nonadrenergic, noncholinergic nerve stimulation by electrical field stimulation.. Bethanechol was used to produce contraction of the smooth muscle strips of distal colon to record a decrease in the tension. Conversely, the IAS smooth muscle strips developed spontaneous tone. In the normal homozygous mice, electrical field stimulation caused a biphasic response, an initial decrease followed by an after-contraction, whereas in Ls/Ls mice, the predominant response was contraction. All smooth muscle strips from normal and Ls/Ls mice produced relaxation in response to sodium nitroprusside and vasoactive intestinal polypeptide.. Ls/Ls mice may serve as an appropriate animal model to investigate the pathogenesis of the inhibitory neurotransmission in Hirschsprung's disease in the distal colon and IAS.

Topics: Anal Canal; Animals; Colon; Disease Models, Animal; Electric Stimulation; Enzyme Inhibitors; Hirschsprung Disease; Mice; Mice, Mutant Strains; Muscle Relaxation; Muscle, Smooth; Neural Inhibition; Nitric Oxide Synthase; Nitroarginine; Peptide Fragments; Reference Values; Rodent Diseases; Synaptic Transmission; Vasoactive Intestinal Peptide

Topics: Adult; Aged; Aged, 80 and over; Anal Canal; Arginine; Defecation; Electric Stimulation; Enteric Nervous System; Hemoglobins; Hirschsprung Disease; Humans; In Vitro Techniques; Infant; Middle Aged; Muscle Relaxation; Neurons; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Nitroprusside; Rectum; Reflex

Nitric oxide (NO) has recently been shown to be a neurotransmitter in the nonadrenergic noncholinergic (NANC) inhibitory nerves in the gastrointestinal tract. To clarify the significance of NO in Hirschsprung's disease (HD), enteric nerve responses in colonic tissue obtained from HD patients were investigated. Colonic tissue specimens were obtained from four patients with HD and from 11 patients without constipation who were used as controls. A mechanograph was used to evaluate in vitro colonic responses to electrical field stimulation (EFS) of the adrenergic and cholinergic nerves before and after treatment with various autonomic nerve blockers, and NG-nitro-L-arginine (L-NNA) and L-arginine with the following results: (1) NANC inhibitory nerves were found to act on normal human colon, but had no effect on aganglionic colon; (2) L-NNA concentration dependently inhibited the relaxation in response to EFS in the normal colon, but had no effect on aganglionic colon; and (3) this inhibitory effect was reversed by L-arginine in the normal colon, but had no effect on the aganglionic colon. Nitric oxide mediates the relaxation reaction of NANC inhibitory nerves in the human colon, but the effect of NO was absent in aganglionic colon. The loss of action by NO may be implicated in the impaired motility observed in aganglionic colon.

Topics: Adolescent; Arginine; Child; Child, Preschool; Colon; Electric Stimulation; Enteric Nervous System; Female; Gastrointestinal Motility; Hirschsprung Disease; Humans; Infant; Male; Nitric Oxide; Nitroarginine