Browse more peptide research, methods and limitations.
Glucocorticoids regulate hypothalamic VIP expression and prolactin secretion but do not affect beta-endorphin, dynorphin A, or met-enkephalin immunostaining in the hypothalamus.
Watanobe, H · Animal Study
Apocarboxypeptidase B-Sepharose selectively adsorbs opioid peptides with C-terminal basic residues, providing a novel separation tool for peptide processing research.
Yasuhara, T; Ohashi, A · In Vitro
Acute central opioid pretreatment produces rapid sensitization to naltrexone, predominantly through mu receptors. This represents an early stage of physical dependence occurring within hours.
Adams, J U; Holtzman, S G · Animal Study
Active morphine raised blood levels of all four opioid peptides in dogs. The inactive mirror form did not. Neither form changed opioid peptide levels in brain fluid.
Adams, M L; Morris, D L; Brase, D A; Dewey, W L · Animal Study
Hemorrhagic hypotension raised brain fluid opioid levels and caused pial artery dilation in newborn pigs. Blood pressure dropped from 63 to 33 mmHg.
Armstead, W M; Mirro, R; Busija, D W; Desiderio, D M; Leffler, C W · Animal Study
Cerebrospinal fluid MERGL levels were significantly low in Parkinson's patients after overnight medication withdrawal. Steady-state levodopa infusion did not restore them.
Baronti, F; Conant, K E; Giuffra, M; Davis, T L; Brughitta, G; Iadarola, M J; Berrettini, W H; Chase, T N; Mouradian, M M · Cross Sectional
Met-enkephalin, leu-enkephalin, and dynorphin decreased inhibitory junction potentials in canine duodenal circular muscle via delta and mu receptors.
Bauer, A J; Szurszewski, J H · Animal Study
Mu-selective agonist DAGO injected into the substantia nigra produced antinociception comparable to the periaqueductal gray. Delta and kappa agonists had no effect.
Baumeister, A A · Animal Study
Peptides synthesized by azide coupling contained mutagenic contaminants undetectable by HPLC. Switching synthesis methods or using counter-current purification eliminated the problem.
Castellino, S; de Castiglione, R; Forino, R; Galantino, M; Pulci, R · In Vitro
Glucocorticoid receptors were found in opioid peptide neurons and other peptidergic neurons, with strong regional variation across the brain.
Cintra, A; Fuxe, K; Solfrini, V; Agnati, L F; Tinner, B; Wikström, A C; Staines, W; Okret, S; Gustafsson, J A · Animal Study
Pro-enkephalin fragments were released at 29-43% of tissue content loss. BAM-8 released at higher rates. The precursor BAM-18 was not released.
Corbett, A D; Gillan, M G; Kosterlitz, H W · Animal Study
Kainic acid seizures increased hippocampal prodynorphin and proenkephalin mRNA while decreasing dynorphin A and met-enkephalin peptide levels, both proportional to seizure severity.
Douglass, J; Grimes, L; Shook, J; Lee, P H; Hong, J S · Animal Study
Chronic constriction injury and inflammation both upregulated spinal preprodynorphin mRNA rapidly and sustainably. Complete nerve transection and crush did not.
Draisci, G; Kajander, K C; Dubner, R; Bennett, G J; Iadarola, M J · Animal Study
Naloxone injection into the caudal ventrolateral medulla caused dose-dependent blood pressure drops. Delta and kappa receptor antagonists reproduced this effect; mu antagonist did not.
Drolet, G; Morilak, D A; Chalmers, J · Animal Study
VIP is diminished in intestinal smooth muscle of Crohn's patients. Substance P receptors are markedly increased at small vessels and lymph nodules in inflamed IBD intestine.
Eysselein, V E; Nast, C C · Review
Mu receptor agonists raised blood glucose and corticosterone. Delta agonist raised fatty acids only. Kappa agonist raised glucose only. Mu antagonist blocked the glucose/corticosterone effects.
Gunion, M W; Rosenthal, M J; Morley, J E; Miller, S; Zib, B; Butler, B; Moore, R D · Animal Study
Morphine inhibited 44% of AV3V neurons in polydipsic STR/N mice vs. 59% in controls. All three opioid receptor types were functional in both strains.
Hattori, Y; Katafuchi, T; Koizumi, K · Animal Study
Pancreatic polypeptides and dynorphin A stimulated feeding in satiated dogs. NPY, galanin, norepinephrine, and GRH did not, despite working in rats.
Inui, A; Okita, M; Nakajima, M; Inoue, T; Sakatani, N; Oya, M; Morioka, H; Okimura, Y; Chihara, K; Baba, S · Animal Study
Central administration of an endopeptidase 24.15 inhibitor enhanced opioid-mediated swim stress antinociception. The effect was reversed by naloxone.
Kest, B; Orlowski, M; Bodnar, R J · Animal Study
Beta-endorphin inhibited POMC mRNA by 65% via delta receptors. Enkephalins also worked through delta receptors. Dynorphin worked through kappa. Mu receptors were not involved.
l'Héreault, S; Barden, N · Animal Study
This landmark 1991 Nature paper introduced the "one-bead, one-peptide" (OBOP) approach to peptide library screening. Each tiny resin bead carries millions of copies of a single unique peptide sequence, and the library contains millions of beads — each with a different peptide. This allows researchers to screen millions of peptide sequences simultaneously for binding to a target receptor, enzyme, or antibody. The method overcame severe limitations of prior approaches: predetermined small libraries were too limited, and phage display libraries were restricted by biology. The OBOP method enabled rapid identification and sequencing of high-affinity peptide ligands from random libraries of millions of candidates.
Lam, K S; Salmon, S E; Hersh, E M; Hruby, V J; Kazmierski, W M; Knapp, R J · Methods Landmark
Leu-enkephalin immunoreactivity was found in many cells of the axolotl anterior pituitary, unlike mammals. Beta-endorphin distribution was similar to other vertebrates.
Leon-Olea, M; Sanchez-Alvarez, M; Piña, A L; Bayon, A · Animal Study
Authentic met-enkephalin and leu-enkephalin were detected in holostean fish and lungfish brains. Dynorphin-related peptides were not detected in either species.
McDonald, L K; Joss, J M; Dores, R M · Animal Study
32 brain peptides are categorized and reviewed across location, synthesis, receptor binding, and function, organized into opioid, pituitary hormone, and miscellaneous peptide groups.
Moore, M R; Black, P M · Review
Human serum biotinidase hydrolyzes enkephalins and dynorphin A (<10-mer) with kcat/Km values similar to its biotin substrate biocytin.
Oizumi, J; Hayakawa, K · In Vitro
All three opioid peptides stimulated adenylate cyclase in olfactory bulb by ~40% above baseline. Beta-endorphin was most potent (EC50 22 nM). Naloxone blocked all effects.
Onali, P; Olianas, M C · In Vitro
Dynorphin A(1-8) approximately doubled acetylcholine release from Torpedo electromotor neurons. The effect was naloxone-reversible and showed strong seasonal variation.
Oron, L; Sarne, Y; Michaelson, D M · Animal Study
Met-enkephalin was significantly elevated in cortex, hippocampus, and brainstem of tg/tg epileptic mice. Beta-endorphin and dynorphin were unchanged.
Patel, V K; Abbott, L C; Rattan, A K; Tejwani, G A · Animal Study
All three opioid peptide classes (enkephalin, dynorphin, endorphin) were detected in embryonic mouse brain before their putative receptors during E11.5 to P1.
Rius, R A; Barg, J; Bem, W T; Coscia, C J; Loh, Y P · Animal Study
Dexfenfluramine's anorectic effect dominated over opioid agonist feeding stimulation. The interaction was not mediated by brain serotonin turnover changes.
Robert, J J; Orosco, M; Rouch, C; Cohen, Y; Jacquot, C · Animal Study
Kappa opioid agonists enhanced auditory nerve compound action potential amplitudes. Mu and delta agonists had no effect. Naloxone altered baseline responses.
Sahley, T L; Kalish, R B; Musiek, F E; Hoffman, D W · Animal Study
Pregnancy and DES treatment altered pituitary met-enkephalin and dynorphin content in patterns paralleling oxytocin and vasopressin changes.
Schriefer, J A · Animal Study
Chronic inflammation increased basal enkephalin release but abolished CRF-stimulated release of all three opioid peptides from the hypothalamus. KCl-stimulated release remained intact.
Shippenberg, T S; Herz, A; Nikolarakis, K · Animal Study
Opiate tolerance involves multiple mechanisms: environmental learning, NMDA receptor involvement, second messenger system adaptations, and altered intracellular signaling. Receptor numbers change minimally.
Trujillo, K A; Akil, H · Review
Chronic low-dose PCB exposure increased serum complement and NK cell activity while altering other immune parameters in rhesus monkeys.
Tryphonas, H; Luster, M I; White, K L; Naylor, P H; Erdos, M R; Burleson, G R; Germolec, D; Hodgen, M; Hayward, S; Arnold, D L · Animal Study
CSF dynorphin A (14.3 fmol/ml) and met-enkephalin-Arg-Phe (35.1 fmol/ml) were normal in fibromyalgia. No evidence of endorphin deficiency.
Vaerøy, Henning; Nyberg, Fred; Terenius, Lars · Cross Sectional
Central and peripheral naloxone increased bleeding volumes before pressure dropped. Brain antibodies against beta-endorphin, alpha-endorphin, and dynorphin A also improved hemorrhage tolerance.
van den Berg, M H; van Giersbergen, P L; Cox-van Put, J; de Jong, W · Animal Study
Full beta-endorphin caused naltrexone-reversible hypotension and bradycardia. N-terminally modified fragments were inactive. Beta-endorphin(1-27) induced both hypertensive and hypotensive responses.
van Giersbergen, P L; de Lang, H; de Jong, W · Animal Study
Column purification validation requires qualification of raw materials, equipment, and process, ideally designed in from the start. Combined with quality control, this ensures batch-to-batch consistency.
· Review
Human placenta contains exclusively kappa opioid receptors (MW ~63,000). They regulate acetylcholine and hCG/placental lactogen release. Receptor numbers correlate with birth weight at term.
Ahmed, M S; Cemerikic, B; Agbas, A · Review
Adrenalectomy and castration independently and interactively regulated hypothalamic CRH mRNA, CRH peptide, opioid peptide content, and CRF-stimulated opioid release.
Almeida, O F; Hassan, A H; Harbuz, M S; Linton, E A; Lightman, S L · Animal Study
Topical dynorphin(1-13) dilated pial arteries during normotension but constricted them during hypotension. It increased CSF vasopressin concentration in both states.
Armstead, W M; Crofton, J T; Share, L; Mirro, R; Zuckerman, S L; Leffler, C W · Animal Study
Transient plasma beta-endorphin elevation in painful AMI (Group II, n=16) that normalized when pain ceased. No changes in painless AMI (Group I, n=12). Met-enkephalin and dynorphin unchanged in both.
Bernardi, P; Fontana, F; Pich, E M; Spampinato, S; Canossa, M · Cross Sectional
In this double-blind trial, delta sleep-inducing peptide (DSIP) showed some objective sleep improvements in chronic insomniacs — higher sleep efficiency and shorter time to fall asleep compared to placebo. One subjective tiredness measure also improved. However, the researchers concluded these effects were weak and potentially confounded by changes in the placebo group. Other measures including subjective sleep quality showed no improvement. The authors' overall conclusion was negative: short-term DSIP treatment is unlikely to provide major therapeutic benefit for chronic insomnia.
Bes, F; Hofman, W; Schuur, J; Van Boxtel, C · Rct
Central TNF-alpha and IL-1-alpha both increased nociceptive thresholds. TNF-alpha decreased locomotion. Naloxone partially reversed TNF-alpha's analgesic effect.
Bianchi, M; Sacerdote, P; Ricciardi-Castagnoli, P; Mantegazza, P; Panerai, A E · Animal Study
Order of potency for hCG release: kappa >>> mu > delta. All three produced bell-shaped dose-response curves. Kappa dominance confirmed.
Cemerikic, B; Schabbing, R; Ahmed, M S · In Vitro
Delta and kappa opioid receptors were co-localized on astroglia from cortex, striatum, and brainstem. Both inhibited adenylate cyclase and modulated beta-receptor-stimulated cAMP.
Eriksson, P S; Hansson, E; Rönnbäck, L · In Vitro
Beta-endorphin (10^-6 M) reduced uterine contractions, prostaglandin synthesis, and calcium uptake. Naloxone did not block it. Other opioids were inactive.
Faletti, A; Bassi, D; Gimeno, A L; Gimeno, M A · Animal Study
Electron microscopy demonstrated direct contact between opioid peptide-containing terminals and tyrosine hydroxylase-positive (dopaminergic) cell bodies in the rat hypothalamus.
Fitzsimmons, M D; Olschowka, J A; Wiegand, S J; Hoffman, G E · Animal Study
Kappa agonists U-62,066E and ethylketocyclazocine inhibited potassium-evoked glutamate and dynorphin B release from mossy fiber synaptosomes. Mu (DAGO) and delta (DPDPE) agonists were inactive.
Gannon, R L; Terrian, D M · In Vitro