Fatty acid incorporation increases the affinity of muscarinic cholinergic receptors for agonists

Bruce Baron*, Yoel Kloog

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Incorporation of unsaturated fatty acids into membrane fragments from rat brain cortex and medulla pons selectively increased the affinity of the muscarinic agonist, carbamylcholine. The affinity and number of binding sites for the labeled antagonist, N-[3H]ethyl-4-piperidyl benzilate was unchanged. The effect on agonist binding was most prominent in the cortex, in which carbamylcholine IC50 values were decreased up to 5-fold. Selectivity of the effect was observed with fatty acids of chain length 18-20 carbons, unsaturation in position 11-12, and a cis conformation of the double bond being most effective. The effects of fatty acids on agonist binding were due primarily to alterations in the affinity constants for the binding reaction, with minor increases in the proportion of high-affinity sites. Transition metals selectively increased the percentage of high-affinity sits in the cortex, but in cis-vaccenic-acid-treated membranes more than additive effects of the metal were observed; both were reversed by GTP. GTP also reversed binding parameters in cis-vaccenic-acid-treated medulla membranes to control level. We conclude that the primary effect of the active fatty acids is to alter the thermocynamic properties of muscarinic agonist binding without markedly inducing interconversion.

Original languageEnglish
Pages (from-to)342-350
Number of pages9
JournalBiochimica et Biophysica Acta - General Subjects
Issue number3
StatePublished - 16 Oct 1984


  • (Rat brain)
  • Fatty acid incorporation
  • Muscarinic cholinergic agonist
  • Receptor affinity


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