Dopamine and norepinephrine in the gastrointestinal tract of mice and the effects of neurotoxins

J Pharmacol Exp Ther. 1988 Feb;244(2):438-42.

Abstract

Evidence is lacking for neurons containing dopamine and acting as a neurotransmitter in the gastrointestinal tract. The relative percentage of dopamine to norepinephrine in noradrenergically innervated tissues (e.g., spleen) is known to be relatively constant within a species, and an increased percentage in any given tissue supports the premise that dopaminergic cells are present. We measured levels of norepinephrine, dopamine and the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) from segments of the gastrointestinal tract of mice after injection of: 1) saline (control); 2) 6-hydroxydopamine (6-OHDA); or 3) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. In control tissues the ratio of dopamine/norepinephrine was higher (P less than .001) than in the spleen; DOPAC was present and the DOPAC/dopamine ratios were similar to those in the central nervous system (where dopaminergic neurons are present). Dopamine and norepinephrine were decreased by 6-OHDA in most myenteric plexus/smooth muscle tissues compared with controls and DOPAC was unmeasurable in most samples after 6-OHDA. In contrast, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine decreased norepinephrine but not dopamine in the smooth muscle/myenteric plexus. High dopamine/norepinephrine percentages, 6-OHDA depletion of dopamine and presence of DOPAC together suggest the presence of dopamine-containing neurons in the myenteric plexus of the gastrointestinal tract of mice.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine
  • 3,4-Dihydroxyphenylacetic Acid / analysis
  • Animals
  • Brain Chemistry / drug effects
  • Digestive System / analysis*
  • Digestive System / drug effects
  • Dopamine / analysis*
  • Hydroxydopamines / pharmacology
  • Intestinal Mucosa / analysis
  • Male
  • Mice
  • Myenteric Plexus / analysis
  • Neurotoxins / pharmacology*
  • Norepinephrine / analysis*
  • Oxidopamine
  • Pyridines / pharmacology

Substances

  • Hydroxydopamines
  • Neurotoxins
  • Pyridines
  • 3,4-Dihydroxyphenylacetic Acid
  • Oxidopamine
  • 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine
  • Dopamine
  • Norepinephrine