Characterization and visualization of rat and guinea pig brain. kappa. opioid receptors: Evidence for. kappa. sub 1 and. kappa. sub 2 opioid receptors

Journal Article · Wed Jun 01 00:00:00 EDT 1988 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.85.11.4061· OSTI ID:5517777

Zukin, R S; Eghbali, M; Olive, D; Unterwald, E M; Tempel, A ^[1]

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1. Albert Einstein College of Medicine, Bronx, NY (USA)

{kappa} opioid receptors ({kappa} receptors) have been characterized in homogenates of guinea pig and rat brain under in vitro binding conditions. {kappa} receptors were labeled by using the tritiated prototypic {kappa} opioid ethylketocyclazocine under conditions in which {mu} and {delta} opioid binding was suppressed. In the case of guinea pig brain membranes, a single population of high-affinity {kappa} opioid receptor sites was observed. In contrast, in the case of rat brain, two populations of {kappa} sites were observed. To test the hypothesis that the high- and low-affinity {kappa} sites represent two distinct {kappa} receptor subtypes, a series of opioids were tested for their abilities to compete for binding to the two sites. U-69,593 and Cambridge 20 selectively displaced the high-affinity {kappa} site in both guinea pig and rat tissue, but were inactive at the rat-brain low-affinity site. Other {kappa} opioid drugs competed for binding to both sites, but with different rank orders of potency. Quantitative light microscopy in vitro autoradiography was used to visualize the neuroanatomical pattern of {kappa} receptors in rat and guinea pig brain. The distribution patterns of the two {kappa} receptor subtypes of rat brain were clearly different. Collectively, these data provide direct evidence for the presence of two {kappa} receptor subtypes; the U-69,593-sensitive, high-affinity {kappa}{sub 1} site predominates in guinea pig brain, and the U-69,593-insensitive, low-affinity {kappa}{sub 2} site predominates in rat brain.

• OSTI ID: 5517777
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 85:11; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BRAIN
AUTORADIOGRAPHY
RECEPTORS
TISSUE DISTRIBUTION
BIOCHEMICAL REACTION KINETICS
GUINEA PIGS
RATS
TRITIUM COMPOUNDS
ANIMALS
BODY
CENTRAL NERVOUS SYSTEM
DISTRIBUTION
HYDROGEN COMPOUNDS
KINETICS
MAMMALS
MEMBRANE PROTEINS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques