Agonist Regulation of Muscarinic Acetylcholine Receptors in Rat Spinal Cord

John E. Taylor, Tony L. Yaksh, Elliott Richelson

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Abstract: In vitro studies with cultured cells originating from nervous tissue have shown that chronic exposure to muscarinic agonists results in a loss of muscarinic receptors. To determine whether this type of regulation of muscarinic receptor number also occurs in vivo, we infused carbachol into the spinal cords of rats. A single carbachol injection into the lumbar spinal cord caused a significant increase in the nociceptive threshold. This effect of carbachol diminished to control levels after 12 h of repeated agonist injections every 4 h and was blocked by atropine. The desensitization to the antinociceptive effects of carbachol was associated with a loss of muscarinic receptors as determined by the binding of the muscarinic antagonist [3H]quinuclidinyl benzilate. After a 24‐h exposure to carbachol given every 4 h, there was about a 60% loss of binding sites. The loss of muscarinic receptors was also blocked by atropine and was reversible. These results represent direct evidence that a muscarinic agonist can regulate receptor number in the central nervous system and suggest that this loss of receptors is associated with a desensitization to the antinociceptive effects of carbachol injected into the spinal cord.

Original languageEnglish (US)
Pages (from-to)521-524
Number of pages4
JournalJournal of neurochemistry
Volume39
Issue number2
DOIs
StatePublished - Aug 1982

Keywords

  • Agonists
  • Muscarinic
  • Receptors
  • Regulation

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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