Quantitative autoradiography of muscarinic and benzodiazepine receptors in the forebrain of the turtle, Pseudemys scripta
The distribution of muscarinic and benzodiazepine receptors was investigated in the turtle forebrain by the technique of in vitro receptor autoradiography. Muscarinic binding sites were labeled with 1 nM /sup 3/H-quinuclidinyl benzilate (/sup 3/H-QNB), and benzodiazepine sites were demonstrated with the aid of 1 nM /sup 3/H-flunitrazepam (/sup 3/H-FLU). Autoradiograms generated on /sup 3/H-Ultrofilm apposed to tissue slices revealed regionally specific distributions of muscarinic and benzodiazepine binding sites that are comparable with those for mammalian brain. Dense benzodiazepine binding was found in the anterior olfactory nucleus, the lateral and dorsal cortices, and the dorsal ventricular ridge (DVR), a structure with no clear mammalian homologue. Muscarinic binding sites were most dense in the striatum, accumbens, DVR, lateral geniculate, and the anterior olfactory nucleus. Cortical binding sites were studied in greater detail by quantitative analysis of autoradiograms generated by using emulsion-coated coverslips. Laminar gradients of binding were observed that were specific for each radioligand; /sup 3/H-QNB sites were most dense in the inner molecular layer in all cortical regions, whereas /sup 3/H-FLU binding was generally most concentrated in the outer molecular layer and was least dense through all layers in the dorsomedial cortex. Because pyramidal cells are arranged in register in turtle cortex, the laminar patterns of receptor binding may reflect different receptor density gradients along pyramidal cell dendrites.
- Research Organization:
- Stanford Univ. School of Medicine, CA (USA)
- OSTI ID:
- 5445951
- Journal Information:
- J. Comp. Neurol.; (United States), Vol. 265:4
- Country of Publication:
- United States
- Language:
- English
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CHOLINE
BIOCHEMICAL REACTION KINETICS
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AUTORADIOGRAPHY
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CELL NUCLEI
IN VITRO
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TRITIUM COMPOUNDS
TURTLES
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
DRUGS
HYDROXY COMPOUNDS
KINETICS
LABELLED COMPOUNDS
LIPOTROPIC FACTORS
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ORGANIC COMPOUNDS
ORGANS
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QUATERNARY COMPOUNDS
REACTION KINETICS
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550201* - Biochemistry- Tracer Techniques