Distribution of muscarinic receptor subtypes in rat brain as determined in binding studies with AF-DX 116 and pirenzepine
In vitro competition binding experiments with the selective muscarinic antagonists AF-DX 116 and pirenzepine (PZ) vs /sup 3/H-N-methylscopolamine as radioligand revealed a characteristic distribution of muscarinic receptor subtypes in different regions of rat brain. Based on nonlinear least squares analysis, the binding data were compatible with the presence of three different subtypes: the M/sub 1/ receptor (high affinity for PZ), the cardiac M/sub 2/ receptor (high affinity for AF-DX 116) and the glandular M/sub 2/ receptor (low affinity for PZ and AF-DX 116). The highest proportion of M/sub 1/ receptors was found in the hippocampus, while the cerebellum and the hypothalamus were the regions with the largest fraction of the cardiac M/sub 2/ and glandular M/sub 2/ receptors, respectively. In certain brain areas, depending on the relative proportions of the subtypes, flat binding curves were seen for AF-DX 116 and PZ. Based on these data, an approximate distribution pattern of the subtypes in the various brain regions is presented. 19 references, 1 figure, 2 tables.
- Research Organization:
- Instituto De Angeli, Milan, Italy
- OSTI ID:
- 6846924
- Journal Information:
- Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 40:9; ISSN LIFSA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
ANTIPYRETICS
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
CHOLINE
DATA
DISTRIBUTION
DRUGS
EXPERIMENTAL DATA
HYDROXY COMPOUNDS
INFORMATION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIGANDS
LIPOTROPIC FACTORS
MAMMALS
MEMBRANE PROTEINS
NERVOUS SYSTEM
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANS
PROTEINS
QUATERNARY COMPOUNDS
RATS
REACTION KINETICS
RECEPTORS
RODENTS
TISSUE DISTRIBUTION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES