Radioimmunoassay of dermorphin-like peptides in mammalian and non-mammalian tissues

doi:10.1016/0196-9781(81)90009-7

Peptides

Volume 2, Supplement 2, 1981, Pages 45-49

https://doi.org/10.1016/0196-9781(81)90009-7 Get rights and content

Abstract

A selective RIA for D-Ala²-Dermorphin (Der), a natural peptide extracted from amphibian skin, has been developed using an antibody raised in rabbits against Der which has been coupled to BSA through its phenolic hydroxyl groups of tyrosine residues with 2,4-Dichloro-6-methoxy-1,3,5-triazine. The cross-reactivity of this antibody with dermorphin analogs, C- and N-terminal fragments of dermorphin molecule, some opioid and gastrointestinal peptides was tested. Der-like immunoreactivity has been identified in tissue extracts of rats, frog and cephalopoda. Der-like peptides were purified by passing methanol extracts of the tissues through a Sephadex G₂₅ column ( $16×100 cm$ ) eluted with 0.1 M acetic acid at 4°C. Der-like immunoreactivity from neural tissue of Dosidicus gigas, Eledone moscata, and rat brain showed a good agreement with an authentic sample of synthetic dermorphin.

References (4)

Agarwal et al.
Immunochemical differentiation between gastrin and related peptide hormones through a novel conjugation of peptides to protein
Experientia
(1971)
Broccardo et al.
Pharmacological data on dermorphins, a new class of potent opioid peptides from amphibian skin
Br. J. Pharmac.
(1981)

There are more references available in the full text version of this article.

Cited by (41)

The dermorphin peptide family
1996, General Pharmacology
- 1.
  1. In 1980, the skin of certain frogs belonging to the genus Phyllomedusinae was found to contain two new peptides that proved to be selective μ-opioid agonists. Given the name dermorphins, these were the first members of a peptide family that in the past 15 years has grown to reach a total of seven naturally occurring peptides and nearly 30 synthetic analogs.
- 2.
  2. Dermorphin peptides are potent analgesics in rodents and primates, including man. Some dermorphins can enter the blood-brain barrier and produce central antinociception after peripheral administration.
- 3.
  3. The dermorphin family also includes μ₁-opioid receptor selective agonists that produce intense opioid analgesia, but stimulate pulmonary ventilation.
- 4.
  4. Experiments in rats and mice chronically exposed to dermorphins have shown that not only do they have higher antinociceptive efficacy and potency than morphine, but they are also less likely than morphine to produce tolerance, dependence and opiate side effects.
Production and characterization of site-directed antibodies against dermorphin and dermorphin-related peptides
1996, Peptides
To detect and purify endogenous dermorphin-like molecules in mammalian tissues, an immunological approach was developed. Sitedirected antibodies against synthetic dermorphin and related dermorphin peptides were produced. The immunogenic forms of dermorphin were selected to obtain antibodies recognizing different epitopes overlapping the whole dermorphin molecule. One of them specifically recognized the crucial “opioid message” (the N-terminal part of the molecule), which is required for a ligand to exert its full opioid activity. The validity of our immunological approach was analyzed by studying the dermorphin-related peptide distribution in Phyllomedusa sauvagei skin. The finding that tetrapeptide Y-A-G-F-OH was present in Phyllomedusa sauvagei extracts suggested that either the Tyr⁵-Pro⁶ peptidic bond may be relatively unstable or endogenous proteolytic enzymes present in Phyllomedusa skin may inactivate this peptidic bond.
Enter a new post-translational modification: d-amino acids in gene-encoded peptides
1992, Trends in Biochemical Sciences
The post-translational processing of peptides plays a key role in conferring biological activity on those peptides. Recently, ribosomally made peptides that contain d-amino acids at specific positions have been discovered in microorganisms as well as in vertabrates and invertebrates. This points to yet another strategy of circumventing sterochemcal limitations imposed by the genetic code and conveying biological activity to otherwise inert molecules.
The opioid peptides of the amphibian skin
1992, International Journal of Developmental Neuroscience
Cardiovascular and respiratory effects of dermorphin in rats
1990, Pharmacological Research
Electrophysiological effects of dermorphin on locus coeruleus neurons of rat
1990, Neuropharmacology
Intracellular recording was used to study the effects of dermorphin on neurons of the locus coeruleus in the rat, in a totally submerged brain slice preparation. Dermorphin caused the inhibition of spontaneous firing of all neurons of the locus coeruleus tested, with an IC₅₀ of 7 nM. Based on the inhibition of spontaneous firing rate, dermorphin was 16.5 times more potent than morphine. Larger concentrations of dermorphin (30–100 nM) further hyperpolarized the neurons of the locus coeruleus and simultaneously caused a reduction in input resistance. These effects were antagonized by naloxone, with a dissociation equilibrium constant of 0.8 nM. The hyperpolarization of neurons of the locus coeruleus, caused by dermorphin, was reversed at a membrane potential of −112mV in this preparation. Furthermore, this hyperpolarization was blocked by cesium chloride and barium chloride. Thus, these data suggest that dermorphin binds to μ-opioid receptors on the cell membrane of neurons of the locus coeruleus. This leads to opening of the inward-going rectification potassium channels, resulting in the observed hyperpolarization of the membrane.

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Radioimmunoassay of dermorphin-like peptides in mammalian and non-mammalian tissues

Abstract

Immunochemical differentiation between gastrin and related peptide hormones through a novel conjugation of peptides to protein

Experientia

Pharmacological data on dermorphins, a new class of potent opioid peptides from amphibian skin

Br. J. Pharmac.