Characterization of a ( sub 3 H)-5-hydroxtyryptamine binding site in rabbit caudate nucleus that differs from the 5-HT sub 1A , 5-HT sub 1B , 5-HT sub 1C and 5-HT sub 1D subtypes

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Life Sciences; (USA)

DOI:https://doi.org/10.1016/0024-3205(89)90033-7· OSTI ID:5131967

Xiong, Wencheng; Nelson, D L ^[1]

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1. Univ. of Arizona, Tucson (USA)

({sup 3}H)5-HT binding sites were analyzed in membranes prepared from the rabbit caudate nucleus (CN). ({sup 3}H)5-HT labeled both 5-HT{sub 1A} and 5-HT{sub 1C} recognition sites, defined by nanomolar affinity for 8-OH-DPAT and mesulergine respectively; however, these represented only a fraction of total specific ({sup 3}H)5-HT binding. Saturation experiments of ({sup 3}H)5-HT binding in the presence of 100 nM 8-OH-DPAT and 100 nM mesulergine to block 5-HT{sub 1A} and 5-HT{sub 1C} sites revealed that non-5-HT{sub 1A}/non-5-HT{sub 1C} sites represented about 60% of the total 5-HT{sub 1} sites and that they exhibited saturable, high affinity, and homogeneous binding. The pharmacological profile of the non-5-HT{sub 1A}/non-5-HT{sub 1C} sites (designated 5-HT{sub 1R}) also differed from that of 5-HT{sub 1B} and 5-HT{sub 2} sites, but was similar to that of the 5-HT{sub 1D} site. However, significant differences existed between the 5-HT{sub 1D} and 5-HT{sub 1B} sites for their K{sub i} values for spiperone, spirilene, metergoline, and methiothepin. The study of modulatory agents also showed differences between the 5-HT{sub 1R} and 5-HT{sub 1D} sites. In addition, calcium enhanced the effects of GTP on the 5-HT{sub 1R} sites, whereas calcium inhibited the GTP effect on the 5-HT{sub 1D} sites.

• OSTI ID: 5131967
• Journal Information: Life Sciences; (USA), Journal Name: Life Sciences; (USA) Vol. 45:16; ISSN 0024-3205; ISSN LIFSA
• Country of Publication: United States
• Language: English

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550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
AMINES
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
AZOLES
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CALCIUM
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CEREBRAL CORTEX
CEREBRUM
CHEMICAL COMPOSITION
DRUGS
ELEMENTS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INDOLES
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
METALS
NERVOUS SYSTEM
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROTEINS
PYRROLES
RABBITS
RADIOPROTECTIVE SUBSTANCES
REACTION KINETICS
RECEPTORS
SEROTONIN
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
TRYPTAMINES
VERTEBRATES