Innervation of the gastrointestinal tract: patterns of aging

Auton Neurosci. 2007 Oct 30;136(1-2):1-19. doi: 10.1016/j.autneu.2007.04.005. Epub 2007 May 29.

Abstract

The gastrointestinal (GI) tract is innervated by intrinsic enteric neurons and by extrinsic projections, including sympathetic and parasympathetic efferents as well as visceral afferents, all of which are compromised by age to different degrees. In the present review, we summarize and illustrate key structural changes in the aging innervation of the gut, and suggest a provisional list of the general patterns of aging of the GI innervation. For example, age-related neuronal losses occur in both the myenteric plexus and submucosal plexus of the intestines. These losses start in adulthood, increase over the rest of the life span, and are specific to cholinergic neurons. Parallel losses of enteric glia also occur. The extent of neuronal and glial loss varies along an oral-to-anal gradient, with the more distal GI tract being more severely affected. Additionally, with aging, dystrophic axonal swellings and markedly dilated varicosities progressively accumulate in the sympathetic, vagal, dorsal root, and enteric nitrergic innervation of the gut. These dramatic and consistent patterns of neuropathy that characterize the aging autonomic nervous system of the GI tract are candidate mechanisms for some of the age-related declines in function evidenced in the elderly.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Aging / pathology*
  • Animals
  • Autonomic Nervous System Diseases / pathology*
  • Autonomic Nervous System Diseases / physiopathology
  • Enteric Nervous System / pathology*
  • Enteric Nervous System / physiopathology
  • Gastrointestinal Tract / innervation*
  • Gastrointestinal Tract / physiopathology
  • Humans
  • Models, Animal
  • Nerve Degeneration / etiology
  • Nerve Degeneration / pathology
  • Nerve Degeneration / physiopathology
  • Neuroglia / pathology
  • Neurons / pathology