Characterization of dopamine D2 receptors in the pituitary of the African catfish, Clarias gariepinus

Journal Article · Mon Oct 01 00:00:00 EDT 1990 · General and Comparative Endocrinology; (USA)

DOI:https://doi.org/10.1016/0016-6480(90)90154-E· OSTI ID:6011364

Van Asselt, L A; Goos, H J; De Leeuw, R; Peter, R E; Hol, E M; Wassenberg, F P; Van Oordt, P G ^[1]

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1. Univ. of Utrecht (Netherlands)

Dopamine receptors in the pituitary of the African catfish, Clarias gariepinus, were characterized using ({sup 3}H)spiperone as radioligand. Specific binding of ({sup 3}H)spiperone to pituitary membranes reached equilibrium within 60 min of incubation. The binding of the radioligand was tissue specific since the amount of binding was linear with pituitary membrane content in the incubations. In addition, pituitary membranes were observed to bind considerably more ({sup 3}H)spiperone, compared to membrane preparation of various other tissues. Saturation experiments revealed the presence of a single class of high affinity/low capacity binding sites. The binding characteristics, estimated by Scatchard analysis, were: Kd = 3.2 +/- 0.5 x 10(-9) M and Bmax = 105 +/- 5 fmol/mg protein. Specific binding was displaceable with dopamine and with various specific D2 agonists and antagonists. The nature of displacement curves resembles those observed in studies on mammalian dopamine receptors. Binding experiments with cell fractions, obtained after centrifugation of dispersed pituitary cells over a Percoll density gradient, showed that most ({sup 3}H)spiperone binding was obtained in an enriched gonadotropic cell fraction. This observation indicates that the receptor characteristics, estimated with the ({sup 3}H)spiperone assay, are representative for dopamine receptors on the gonadotropic cells.

• OSTI ID: 6011364
• Journal Information: General and Comparative Endocrinology; (USA), Vol. 80:1; ISSN 0016-6480
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
DOPAMINE
RECEPTORS
CHEMICAL COMPOSITION
SPIPERONE
BIOCHEMICAL REACTION KINETICS
CELL MEMBRANES
FISHES
LIGANDS
PITUITARY GLAND
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINES
ANIMALS
AQUATIC ORGANISMS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CELL CONSTITUENTS
DRUGS
ENDOCRINE GLANDS
GLANDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
MEMBRANE PROTEINS
MEMBRANES
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANS
PHENOLS
POLYPHENOLS
PROTEINS
REACTION KINETICS
SYMPATHOMIMETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques