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Age-related changes in the neuromuscular development of the internal anal sphincter

Reiji Nakano1, Thambipillai Sri Paran, Udo Rolle

  • 1The Children's Research Center, Our Lady's Children's Hospital, Dublin 12, Ireland.

Journal of Pediatric Surgery
|June 19, 2008
PubMed

Insights

The internal anal sphincter (IAS) shows age-related neuromuscular development. Immature IAS in premature infants may cause functional intestinal obstruction due to poor muscle and nerve development.

Area of Science:

  • Gastroenterology
  • Developmental Biology
  • Neuroscience

Background:

  • The internal anal sphincter (IAS) is crucial for bowel control.
  • Dysfunction of the IAS is implicated in constipation and incontinence.
  • Premature infants may experience functional bowel obstruction due to an underdeveloped IAS.

Purpose of the Study:

  • To investigate the neuromuscular development of the IAS in pigs across different life stages.
  • To test the hypothesis that a poorly developed IAS contributes to functional bowel obstruction in premature infants.

Main Methods:

  • Immunohistochemical staining of IAS tissue from fetal, newborn, and adolescent pigs (E60, E90, 1 day, 4, and 12 weeks).
  • Antibodies used included PGP9.5 (neurons), α-SMA, caldesmon, calponin, and desmin (smooth muscle components).
  • Quantification of protein expression by grading immunostaining density.

Main Results:

  • PGP9.5-positive ganglion cells were present in the IAS by E60, with increasing size and density with age.
  • Significant differences in PGP9.5, α-SMA, desmin, caldesmon, and calponin immunoreactive fibers were observed between prenatal and postnatal periods.
  • A gradual increase in fiber density was noted from birth to 12 weeks of age.

Conclusions:

  • This study reveals age-related changes in IAS neuron and smooth muscle cell components.
  • Reduced expression of contractile proteins and neurons in the perinatal period may cause motility dysfunction.
  • This dysfunction could underlie functional intestinal obstruction observed in premature infants.
Abstract

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