PUBLICATION
Binding profile of the endogenous novel heptapeptide met-enkephalin-gly-tyr in zebrafish and rat brain
- Authors
- Gonzalez-Nuñez, V., Arsequell, G., Szemenyei, E., Toth, G., Valencia, G., and Rodriguez, R.E.
- ID
- ZDB-PUB-050523-3
- Date
- 2005
- Source
- The Journal of pharmacology and experimental therapeutics 314(2): 862-867 (Journal)
- Registered Authors
- González Nuñez, Veronica, Rodriguez, Raquel E.
- Keywords
- none
- MeSH Terms
-
- Amino Acid Substitution
- Animals
- Binding, Competitive/drug effects
- Brain/metabolism*
- Diprenorphine/pharmacokinetics
- Enkephalin, Methionine/analogs & derivatives*
- Enkephalin, Methionine/chemical synthesis
- Enkephalin, Methionine/pharmacokinetics
- Female
- In Vitro Techniques
- Male
- Membranes/drug effects
- Membranes/metabolism
- Methionine/metabolism
- Naloxone/pharmacokinetics
- Narcotic Antagonists/pharmacokinetics
- Rats
- Species Specificity
- Zebrafish
- PubMed
- 15901806 Full text @ J. Pharmacol. Exp. Ther.
Citation
Gonzalez-Nuñez, V., Arsequell, G., Szemenyei, E., Toth, G., Valencia, G., and Rodriguez, R.E. (2005) Binding profile of the endogenous novel heptapeptide met-enkephalin-gly-tyr in zebrafish and rat brain. The Journal of pharmacology and experimental therapeutics. 314(2):862-867.
Abstract
Zebrafish is considered as a model organism not only for the study of the biological functions of vertebrates but also as a tool to analyze the effects of some drugs or toxic agents. Five opioid precursor genes homologous to the mammalian opioid propeptide genes have been identified recently and one of these, the zebrafish proenkephalin (zfPENK), codes a novel heptapeptide, the Met-Enkephalin-Gly-Tyr (MEGY). In order to analyze the pharmacological properties of this novel ligand, we have labelled it with tritium ([(3)H]-MEGY). Besides, we have also synthesized two analogues: (D-Ala(2))-MEGY (Y-D-Ala-GFMGY) and (D-Ala(2), Val(5))-MEGY (Y-D-Ala-GFVGY). The binding profile of these three agents has been studied in zebrafish and rat brain membranes. [(3)H]-MEGY presents one binding site in zebrafish as well as in rat brain membranes, although it shows a slight higher affinity in zebrafish brain. The observed saturable binding is displaced by naloxone, thus confirming the opioid nature of the binding sites. Competition binding assays indicate that the Methionine residue is essential for high affinity binding of MEGY and probably of other peptidic agonists in zebrafish, while the change of a Gly for a D-Ala does not affect dramatically the ligand affinity. Our results show that the percentage of [(3)H]-MEGY displaced by all the ligands studied is higher than 100%, thus inferring that naloxone (used to determine non-specific binding) is not binding to all the sites labelled by [(3)H]-MEGY. We can hence deduct that some of the MEGY-binding sites should not be considered as classical opioid sites.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping