FMRFamide: low affinity inhibition of opioid binding to rabbit brain membranes
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-; TRN: 87-007013
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Partial characterization of a novel endogenous opioid in human cerebrospinal fluid
Dihydromorphine-peptide hybrids with delta receptor agonistic and mu receptor antagonistic actions
Related Subjects
MORPHINE
RECEPTORS
PEPTIDES
BIOLOGICAL EFFECTS
BIOCHEMICAL REACTION KINETICS
AMIDES
BRAIN
CELL MEMBRANES
DOSE-RESPONSE RELATIONSHIPS
IMMUNE REACTIONS
INHIBITION
LIGANDS
RABBITS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALKALOIDS
ANALGESICS
ANIMALS
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DRUGS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NARCOTICS
NERVOUS SYSTEM
OPIUM
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques