Browse more peptide research, methods and limitations.
All four prodynorphin end products detected in turtle, lizard, and alligator brains by radioimmunoassay and chromatography.
Goldsmith, A M; Sei, C A; Lance, V; Dores, R M · Animal Study
Salmonella genes required for antimicrobial peptide resistance were also required for macrophage survival and mouse virulence. Mutants were sensitive to both insect and mammalian peptides.
Groisman, E A; Parra-Lopez, C; Salcedo, M; Lipps, C J; Heffron, F · Animal Study
Beta-endorphin and POMC processing products were found in rat spinal cord cells, suggesting local production beyond supraspinal sources.
Gutstein, Howard B; Bronstein, David M; Akil, Huda · Animal Study
Thymic hormones (thymosin alpha-1, thymulin, thymopoietin) decline with age alongside thymic involution, and their supplementation shows potential for partially restoring age-related immune deficits.
Hadden, J W; Malec, P H; Coto, J; Hadden, E M · Review
Dynorphin immunoreactivity detected in both inflammatory cells and cutaneous sensory nerve fibers in Freund's adjuvant-inflamed rat paw tissue.
Hassan, A H; Pzewłocki, R; Herz, A; Stein, C · Animal Study
Both seizure types caused initial opioid release. Long-term: enkephalin biosynthesis increased, dynorphin biosynthesis drastically decreased. These peptides are in distinct hippocampal pathways.
Hong, J S · Animal Study
ICV alpha-endorphin (2.5-10 nmol), beta-endorphin (0.38-1.5 nmol), and gamma-endorphin (2.5-10 nmol) did not affect conditioned suppression or forced swim immobility in mice.
Katoh, A; Nabeshima, T; Ukai, R; Kameyama, T · Animal Study
VIP (20 nM-1 microM) induced neurogenic gut contractions via acetylcholine and substance P. Dynorphin (100 nM) and somatostatin (60 nM) abolished these contractions.
Katsoulis, S; Schmidt, W E; Clemens, A; Schwörer, H; Creutzfeldt, W · Animal Study
Dynorphin(1-13) ICV produced dose-dependent antinociception. It prevented acute morphine tolerance development. Potency order: beta-endorphin > morphine > dynorphin >> met-enkephalin.
Kishioka, S; Morita, N; Kitabata, Y; Yamanishi, T; Miyamoto, Y; Ozaki, M; Yamamoto, H · Animal Study
SHR rats had distinct age-dependent opioid peptide profiles in brain regions linked to blood pressure control. Antihypertensive drugs partially normalized these changes.
Li, S J; Wong, S C; Hong, J S; Ingenito, A J · Animal Study
Delta opioid receptors primarily mediate adenylate cyclase stimulation in olfactory bulb. Deltorphin I EC50 = 6.7 nM. Mu receptors contribute. Kappa receptors inactive.
Olianas, M C; Onali, P · In Vitro
DMEPA (enkephalin analog) inhibited estradiol-induced uterine DNA synthesis by ~50% when given 1-2 hours before measurement. Naloxone partially reversed the effect.
Ordög, T; Vértes, Z; Vértes, M · Animal Study
Chimeric peptides coupling opioid peptides to BBB transport vectors allow brain delivery of enkephalin and dynorphin analogs in vivo. The strategy has advantages for addiction drug development.
Pardridge, W M · Review
Intrathecal mu and delta agonists produced enhanced antinociception in monoarthritic rats with greater cAMP inhibition. Kappa agonists showed no enhancement.
Przewłocka, B; Dziedzicka, M; Lasoń, W; Przewłocki, R · Animal Study
All three opioid precursor mRNAs detected in inflamed tissue. Opioid peptides localized to immune cells. Local opioid blockade increased pain, proving functional significance.
Przewłocki, R; Hassan, A H; Lason, W; Epplen, C; Herz, A; Stein, C · Animal Study
NEP inhibitor SQ 28,603 markedly potentiated BNP-32 responses in SHR and monkeys. BNP was more resistant to NEP degradation than ANP. Cyclic GMP responses also potentiated.
Seymour, A A; Asaad, M M; Abboa-Offei, B E; Rovnyak, P L; Fennell, S; Rogers, W L · Animal Study
Blood levels of procollagen peptides — particularly procollagen type III N-propeptide (PIIINP) — tracked with the severity of liver scarring in both schistosomiasis and alcoholic liver disease. PIIINP was significantly elevated in all schistosomiasis patient groups compared to healthy controls (p<0.01), and patients with worse scarring on biopsy had higher PIIINP levels (p<0.05). In alcoholic patients, PIIINP was even higher and rose with disease severity. Interestingly, procollagen type I C-propeptide was only elevated during early infection and decreased as disease progressed, suggesting it reflects early-stage collagen production while PIIINP better captures ongoing active fibrosis. Different collagen markers appeared to track different aspects of the scarring process — synthesis versus degradation.
Shahin, M; Schuppan, D; Waldherr, R; Risteli, J; Risteli, L; Savolainen, E R; Oesterling, C; Abdel Rahman, H M; el Sahly, A M; Abdel Razek, S M · Observational
Capsaicin reduced spinal SP and NKA without changing NK1 receptor mRNA. Haloperidol increased basal ganglia SP mRNA without changing NK1 receptor mRNA.
Sivam, S P; Krause, J E · Animal Study
Native opioid peptides did not affect PMN respiratory burst. Opioid peptides modified by activated oxygen species enhanced PMA-stimulated respiratory burst.
Slaoui-Hasnaoui, A; Guerin, M C; Le Doucen, C; Loubatiere, J; Torreilles, J · In Vitro
Met-enkephalin release from synaptosomes was calcium-dependent with distinct kinetics. Release correlated with intraterminal free calcium but showed a different relationship than classical transmitters.
Verhage, M; Ghijsen, W E; Wiegant, V M · In Vitro
Lactoferricin inhibited Listeria monocytogenes (4 serotypes) at 0.3-9 micrograms/ml. Bactericidal concentrations were slightly higher. Effectiveness comparable to clinical antibiotics.
Wakabayashi, Hiroyuki; Bellamy, Wayne; Takase, Mitsunori; Tomita, Mamoru · In Vitro
Exogenous opioids increased peristaltic threshold volume. Naloxone decreased it, indicating endogenous opioids tonically modulate peristaltic triggering.
Waterman, S A; Costa, M; Tonini, M · Animal Study
GHK-Cu induced dose-dependent increases in both secreted and cell-associated glycosaminoglycan synthesis by normal human fibroblasts.
Wegrowski, Y; Maquart, F X; Borel, J P · In Vitro
Thymosin beta 4 peaked early and declined with age. hCG challenge depressed thymosin beta 4. Testosterone modulated both thymosin beta 4 and alpha 1 levels. Castration altered the patterns.
Wise, T H · Animal Study
CRF fibers terminate within the hypothalamus and directly modulate the release of growth hormone, gonadotropins, and opioid peptides through local synaptic connections.
Almeida, O F; Hassan, A H; Holsboer, F · Review
Plasma and CSF levels of all three opioid peptides were elevated in asphyxiated newborns vs. controls, with highest levels in those with cerebral injury.
Cao, L; Qian, P D; Jing, L J; Liang, Q J; Zhao, Z Z · Cross Sectional
Tetrahymena has a functional opioid receptor that inhibits phagocytosis. Morphine most potent, beta-endorphin second. Naloxone-reversible. Receptor predates nervous systems.
Chiesa, R; Silva, W I; Renaud, F L · In Vitro
Naloxone significantly increased plasma oxytocin on days 15, 18, and 21 of pregnancy but not in non-pregnant, early pregnant, or post-partum rats.
Douglas, A J; Dye, S; Leng, G; Russell, J A; Bicknell, R J · Animal Study
Rat heart has a non-opioid dynorphin A(1-13) binding site: Kd 285 nM, Bmax 215 pmol/mg protein. Trypsin-sensitive. Inhibited by Zn2+ and Mg2+. Standard opioid ligands do not compete.
Dumont, M; Lemaire, S · In Vitro
ANF, beta-endorphin, met-enkephalin, dynorphin, and noradrenaline were all elevated in acute CHF. Higher levels correlated with greater severity.
Fontana, F; Bernardi, P; Pich, E M; Capelli, M; Bortoluzzi, L; Spampinato, S; Canossa, M · Cross Sectional
L-692,429 (0.001-1.0 mg/kg IV) produced dose-dependent GH release in healthy young men. At 1 mg/kg, response was comparable to GHRH-(1-29). Safe and well tolerated.
Gertz, B J; Barrett, J S; Eisenhandler, R; Krupa, D A; Wittreich, J M; Seibold, J R; Schneider, S H · RCT
CSF beta-endorphin was significantly decreased in functional abdominal pain patients. Met-enkephalin and dynorphin were unchanged. Pain sensitivity was increased.
Jørgensen, L S; Bach, F W; Christiansen, P; Raundahl, U; Ostgaard, S; Ekman, R · Cross Sectional
Lead exposure alters brain opioid peptide concentrations and receptor binding across multiple brain regions, potentially explaining neurological toxicity symptoms.
Kitchen, I · Review
Asp95Asn mutation in delta opioid receptor eliminated selective high-affinity agonist binding while preserving antagonist binding. Single residue determines agonist selectivity.
Kong, H; Raynor, K; Yasuda, K; Moe, S T; Portoghese, P S; Bell, G I; Reisine, T · In Vitro
GHK-Cu significantly stimulated connective tissue accumulation and collagen synthesis in rat wounds in vivo, confirming its wound-healing potential first observed in cell culture.
Maquart, F X; Bellon, G; Chaqour, B; Wegrowski, J; Patt, L M; Trachy, R E; Monboisse, J C; Chastang, F; Birembaut, P; Gillery, P · Animal Study
Morphine produced distinct changes in multiple CSF opioid peptide species, with patterns differing from plasma changes. HPLC confirmed specific peptide identification.
Natsuki, R; Dewey, W L · Animal Study
Opioid peptides acting through all three receptor types (mu, delta, kappa) enhance non-adrenergic non-cholinergic inhibitory responses in the duodenum, while serotonin reduces them.
Postorino, A; Serio, R; Mulè, F; Adamo, E B; Di Giovanni, G; Marini, R · Animal Study
Thymosin alpha 1 fully restored cocaine-suppressed antibody responses. Thymopentin partially restored them. Effect confirmed at the individual splenocyte level.
Ravagnan, G; Falchetti, R; Lanzilli, G; Di Francesco, P; Gaziano, R; Favalli, C; Garaci, E · Animal Study
Chronic ICV NPFF (5 micrograms/h for 10 days) downregulated mu opioid binding sites. Dynorphin and enkephalin mRNA were unchanged.
Rothman, R B; Brady, L S; Xu, H; Long, J B · Animal Study
Weight-loss-promoting phenylpiperidine antagonists like LY255582 had high affinity for the kappa-2B binding site. Non-weight-loss compounds did not.
Rothman, R B; Xu, H; Char, G U; Kim, A; De Costa, B R; Rice, K C; Zimmerman, D M · Animal Study
Proenkephalin and prodynorphin mRNA found in NTS and other medullary nuclei. Unilateral vagotomy increased opioid mRNA in ipsilateral NTS.
Rutherfurd, S D; Gundlach, A L · Animal Study
Cancer pain patients had altered CSF neuropeptide profiles. Spinal opioid therapy changed pain scores and further modified CSF peptide levels.
Samuelsson, H; Ekman, R; Hedner, T · Cross Sectional
Post-synaptic mu/delta receptors inhibiting DA-stimulated adenylate cyclase showed different endogenous peptide affinity profiles than presynaptic mu, delta, and kappa receptors.
Schoffelmeer, A N; De Vries, T J; Hogenboom, F; Mulder, A H · In Vitro
BPC 157 prevented liver necrosis and fatty changes in bile duct ligation, restraint stress, and CCl4 models. Effective orally and intraperitoneally. Outperformed bromocriptine, amantadine, and somatostatin.
Sikiric, P; Seiwerth, S; Grabarevic, Z; Rucman, R; Petek, M; Rotkvic, I; Turkovic, B; Jagic, V; Mildner, B; Duvnjak, M · Animal Study
BPC 157 from gastric juice shows broad organoprotection across multiple stress models. The stomach may initiate a body-wide protective response during stress via peptide mediators.
Sikirić, P; Petek, M; Rucman, R; Seiwerth, S; Grabarević, Z; Rotkvić, I; Turković, B; Jagić, V; Mildner, B; Duvnjak, M · Review
All three opioid peptides found in synovial immune cells. Intra-articular naloxone increased post-surgical knee pain, proving endogenous opioids provide functional local analgesia.
Stein, C; Hassan, A H; Lehrberger, K; Giefing, J; Yassouridis, A · Cross Sectional
Spinal dynorphin A and met-enkephalin mediate bremazocine's pain relief but not morphine's, showing distinct opioid signaling pathways.
Tseng, L F; Collins, K A · Animal Study
Receptor-selective opioid peptides (DAMGO, dynorphin A, DPLPE) had no effect on low-dose apomorphine-induced behavioral suppression.
Ukai, M; Toyoshi, T; Kameyama, T · Animal Study
Leu-enkephalin at 0.2 micromolar increased spontaneous beating rate in SHR atria but not in normal rat atria, across ages 4 to 16 weeks.
Wong, S C; Ingenito, A J · Animal Study
Big dynorphin (prodynorphin 209-240) caused a 5.1-fold increase in serum prolactin in turkeys, mediated through kappa opioid receptors.
Youngren, O M; Silsby, J L; Phillips, R E; el Halawani, M E · Animal Study