Coincident signalling between the Gi/Go-coupled delta-opioid receptor and the Gq-coupled m3 muscarinic receptor at the level of intracellular free calcium in SH-SY5Y cells

J Neurochem. 2001 Mar;76(6):1688-700. doi: 10.1046/j.1471-4159.2001.00185.x.


In SH-SY5Y cells, activation of delta-opioid receptors with [D-Pen(2,5)]-enkephalin (DPDPE; 1 microM) did not alter the intracellular free Ca(2+) concentration [Ca(2+)](i). However, when DPDPE was applied during concomitant Gq-coupled m3 muscarinic receptor stimulation by carbachol or oxotremorine-M, it produced an elevation of [Ca(2+)](i). The DPDPE-evoked increase in [Ca(2+)](i) was abolished when the carbachol-sensitive intracellular Ca(2+) store was emptied. There was a marked difference between the concentration-response relationship for the elevation of [Ca(2+)](i) by carbachol (EC(50) 13 microM, Hill slope 1) and the concentration-response relationship for carbachol's permissive action in revealing the delta-opioid receptor-mediated elevation of [Ca(2+)] (EC(50) 0.7 mM; Hill slope 1.8). Sequestration of free G protein beta gamma dimers by transient transfection of cells with a beta gamma binding protein (residues 495-689 of the C terminal tail of G protein-coupled receptor kinase 2) reduced the ability of delta opioid receptor activation to elevate [Ca(2+)](i). However, DPDPE did not elevate either basal or oxotremorine-M-evoked inositol phosphate production indicating that delta-opioid receptor activation did not stimulate phospholipase C. Furthermore, delta-opioid receptor activation did not result in the reversal of muscarinic receptor desensitization, membrane hyperpolarization or stimulation of sphingosine kinase. There was no coincident signalling between the delta-opioid receptor and the lysophosphatidic acid receptor which couples to elevation of [Ca(2+)](i) in SH-SY5Y cells by a PLC-independent mechanism. In SH-SY5Y cells the coincident signalling between the endogenously expressed delta-opioid and m3 muscarinic receptors appears to occur in the receptor activation-Ca(2+) release signalling pathway at a step after the activation of phospholipase C.

MeSH terms

  • Animals
  • CHO Cells
  • Calcium / physiology*
  • Carbachol / pharmacology*
  • Cricetinae
  • Enkephalin, D-Penicillamine (2,5)- / pharmacology*
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism*
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • Humans
  • Kinetics
  • Neuroblastoma
  • Oxotremorine / pharmacology*
  • Receptor Cross-Talk / drug effects
  • Receptor Cross-Talk / physiology*
  • Receptor, Muscarinic M3
  • Receptors, Muscarinic / drug effects
  • Receptors, Muscarinic / physiology*
  • Receptors, Opioid, delta / drug effects
  • Receptors, Opioid, delta / physiology*
  • Transfection
  • Tumor Cells, Cultured


  • Receptor, Muscarinic M3
  • Receptors, Muscarinic
  • Receptors, Opioid, delta
  • Oxotremorine
  • Enkephalin, D-Penicillamine (2,5)-
  • Carbachol
  • GTP-Binding Protein alpha Subunits, Gi-Go
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • Heterotrimeric GTP-Binding Proteins
  • Calcium