Coupling of muscarinic receptors to GTP proteins in postmortem human brain--alterations in Alzheimer's disease

Neurosci Lett. 1993 Feb 5;150(1):39-43. doi: 10.1016/0304-3940(93)90103-r.


The coupling of muscarinic agonist receptors to guanine nucleotide-binding (G) proteins was investigated in the frontal, temporal cortices and thalamus of control and Alzheimer brains by using carbachol in competition experiments with [3H]QNB. In the presence of GppNHp, the carbachol/[3H]QNB competition binding data showed a 6-fold increase in the high-affinity muscarinic agonist coefficient (Ki high) in the thalami of control brains and a significantly increased proportion of low-affinity agonist binding sites (Bmax low) in the temporal cortices of control brains, while no significant effect of GppNHp was observed in Alzheimer brains. The results suggest a disturbance of the muscarinic receptor-G protein coupling in Alzheimer's disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / metabolism*
  • Alzheimer Disease / pathology
  • Autopsy
  • Binding, Competitive
  • Brain / metabolism*
  • Brain / pathology
  • Carbachol / pharmacology
  • Female
  • Frontal Lobe / metabolism
  • GTP-Binding Proteins / analysis
  • GTP-Binding Proteins / metabolism*
  • Guanylyl Imidodiphosphate / pharmacology
  • Humans
  • Kinetics
  • Male
  • Quinuclidinyl Benzilate / metabolism
  • Receptors, Muscarinic / analysis
  • Receptors, Muscarinic / metabolism*
  • Reference Values
  • Temporal Lobe / metabolism
  • Thalamus / metabolism


  • Receptors, Muscarinic
  • Guanylyl Imidodiphosphate
  • Quinuclidinyl Benzilate
  • Carbachol
  • GTP-Binding Proteins