Ancient Fish Have Enkephalin Peptides But No Dynorphin in Their Pituitary
Holostean fish have met-enkephalin and leu-enkephalin in a 3:1 ratio plus a novel modified form in their pituitary — but no prodynorphin-derived peptides.
Quick Facts
What This Study Found
Holostean fish have enkephalin peptides with a 3:1 met-to-leu ratio and a novel modified met-enkephalin form, but no detectable prodynorphin-derived peptides.
Key Numbers
How They Did This
Pituitary and brain extracts were analyzed by immunohistochemistry, reverse phase HPLC with radioimmunoassay, and enzymatic digestion to detect extended forms.
Why This Research Matters
This suggests the enkephalin and dynorphin opioid systems may have evolved at different times. The enkephalin system appears more ancient, present even in primitive fish.
The Bigger Picture
The absence of dynorphin peptides in ancient fish suggests the prodynorphin system evolved later. Studying primitive species reveals how the opioid peptide families diversified over evolution.
What This Study Doesn't Tell Us
This was an animal study in a single fish species. The antisera used were designed for mammalian peptides and might not detect all fish opioid variants. Absence of detection does not prove absence.
Questions This Raises
- ?When did the dynorphin system evolve?
- ?Is the novel fish enkephalin form biologically active?
Trust & Context
- Key Stat:
- No prodynorphin in ancient fish Suggesting the dynorphin system evolved after the enkephalin system
- Evidence Grade:
- Preliminary — comparative biochemistry in a single ancient fish species.
- Study Age:
- Published in 1989 — contributed to understanding opioid system evolution.
- Original Title:
- Detection of Met-enkephalin and Leu-enkephalin in the posterior pituitary of the holostean fish, Amia calva.
- Published In:
- Peptides, 10(5), 951-6 (1989)
- Authors:
- Dores, R M(5), McDonald, L K(2), Crim, J W
- Database ID:
- RPEP-00109
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Why study opioid peptides in fish?
Comparing opioid systems across species reveals which peptides are ancient and which evolved later. This helps understand the fundamental vs specialized functions of each peptide family.
What is a holostean fish?
An ancient lineage of bony fish that branched off before modern teleost fish. They are living fossils that provide a window into the evolutionary past of vertebrate biology.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-00109APA
Dores, R M; McDonald, L K; Crim, J W. (1989). Detection of Met-enkephalin and Leu-enkephalin in the posterior pituitary of the holostean fish, Amia calva.. Peptides, 10(5), 951-6.
MLA
Dores, R M, et al. "Detection of Met-enkephalin and Leu-enkephalin in the posterior pituitary of the holostean fish, Amia calva.." Peptides, 1989.
RethinkPeptides
RethinkPeptides Research Database. "Detection of Met-enkephalin and Leu-enkephalin in the poster..." RPEP-00109. Retrieved from https://rethinkpeptides.com/research/dores-1989-detection-of-metenkephalin-and
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.