FMRFamide: low affinity inhibition of opioid binding to rabbit brain membranes

Conference · Wed Mar 05 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:7119570

Zhu, X Z; Raffa, R B

FMRFamide (Phe-Met-Arg-Phe-NH/sub 2/) was first isolated from the ganglia of molluscs by Price and Greenberg in 1977. The peptide was subsequently shown to have diverse actions on various types of molluscan and mammalian tissues. The presence of immunoreactive FMRFamide-like material (irFMRF) in multiple areas of rat brain, spinal cord, and gastrointestinal tract suggests that irFMRF may have a physiological role in mammals. Tang, Yang and Costa recently demonstrated that FMRFamide attenuates morphine antinociception in rats and postulated, based on this and several other lines of evidence, that irFMRF might be an endogenous opioid antagonist. In the present study, they tested the ability of FMRFamide to inhibit the binding of opioid receptor ligands to rabbit membrane preparations. FMRFamide inhibited the specific binding of both /sup 3/(H)-dihydromorphine and /sup 3/(H)-ethylketocyclazocine (IC/sub 50/ = 14 ..mu..M and 320 ..mu..M, respectively) in a dose-related manner, suggesting that FMRFamide may affect binding to at least two types of opioid receptors (mu and kappa). These data are consistent with the concept that irFMRF might act as an endogenous opioid antagonist. However, the low affinity of FMRFamide leaves open the possibility of another mechanism of opioid antagonism, such as neuromodulation.

• Research Organization: Temple Univ. School of Medicine, Philadelphia, PA
• OSTI ID: 7119570
• Report Number(s): CONF-8604222-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:4
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALOIDS
AMIDES
ANALGESICS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BODY
BRAIN
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DOSE-RESPONSE RELATIONSHIPS
DRUGS
IMMUNE REACTIONS
INHIBITION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIGANDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MORPHINE
NARCOTICS
NERVOUS SYSTEM
OPIUM
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PEPTIDES
PROTEINS
RABBITS
REACTION KINETICS
RECEPTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES