κ Opioid Receptor/KOR
κ opioid receptor (KOR) is a conventional opioid receptor activated by endogenous dynorphin peptides and classified with µ (MOR) and δ (DOR) opioid receptors[1]. Mechanistically, KOR signaling can be evaluated through G protein interaction, β-arrestin 2 recruitment, calcium mobilization, dynamic mass redistribution, and dynorphin-stimulated[³⁵S]GTPγS binding[2][3]. Dynorphin peptides and nonpeptide agonists both activate MAPK, while dynorphin peptides selectively promote receptor internalization and downregulation in rKOR-expressing CHO cells[4]. In pain models, KOR deletion affects spinally mediated thermal nociception and chemical visceral pain, distinguishing KOR function from MOR and DOR patterns[5]. In disease-relevant research, KOR ligands have been studied for pain, itch, substance use disorders, depression, and schizophrenia-related symptomatology[3][6][7][8]. Compared with related isoforms, KOR is distinct because dynorphin peptides can stimulate G protein signaling promiscuously in striatum, whereas U69,593 is highly selective for KOR[3]. For experimental applications, dynorphin A, U-69,593, and related peptides act as agonists, while norbinaltorphimine and other antagonists help define KOR-dependent signaling, selectivity, and endogenous-system responses[2][3].
References:
- [1]. Borsodi A, et al. Opioid receptors in GtoPdb v.2025.1. IUPHAR/BPS Guide Pharmacol CITE. 2025;2025(1).
- [2]. Sturaro C, et al. Pharmacology of Kappa Opioid Receptors: Novel Assays and Ligands. Front Pharmacol. 2022 Apr 21;13:873082. [Content Brief]
- [3]. Zhou L, et al. Characterization of kappa opioid receptor mediated, dynorphin-stimulated [35S]GTPγS binding in mouse striatum for the evaluation of selective KOR ligands in an endogenous setting. Neuropharmacology. 2015 Dec;99:131-41. [Content Brief]
- [4]. Jordan BA, et al. Kappa opioid receptor endocytosis by dynorphin peptides. DNA Cell Biol. 2000;19(1):19-27.
- [5]. Martin M, et al. Acute antinociceptive responses in single and combinatorial opioid receptor knockout mice: distinct mu, delta and kappa tones. Eur J Neurosci. 2003 Feb;17(4):701-8. [Content Brief]
- [6]. Ko MC, et al. Pleiotropic Effects of Kappa Opioid Receptor-Related Ligands in Non-human Primates. Handb Exp Pharmacol. 2022;271:435-452. [Content Brief]
- [7]. Phan NQ, et al. Systemic kappa opioid receptor agonists in the treatment of chronic pruritus: a literature review. Acta Derm Venereol. 2012 Sep;92(5):555-60. [Content Brief]
- [8]. Clark SD, et al. The Role of Dynorphin and the Kappa Opioid Receptor in the Symptomatology of Schizophrenia: A Review of the Evidence. Biol Psychiatry. 2019 Oct 1;86(7):502-511. [Content Brief]
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κ Opioid Receptor/KOR Related Products (90)
Related Products (90)
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Matrine
0 ImagesMatrine (Matridin-15-one) is an alkaloid found in plants from the Sophora genus that can act as a kappa opioid receptor and u-receptor agonist. Matrine has a variety of pharmacological effects, including anti-cancer, anti-oxidative stress, anti-inflammation and anti-apoptosis effects. Matrine is potential in the research of disease like human non-small cell lung cancer, hepatoma, papillary thyroid cancer and acute kidney injury (AKI).
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Norbinaltorphimine dihydrochloride
0 ImagesSynonyms: nor-Binaltorphimine dihydrochloride; nor-BNI dihydrochlorideNorbinaltorphimine dihydrochloride (nor-Binaltorphimine dihydrochloride; nor-BNI dihydrochloride) is a selective, long-acting competitive antagonist of the κ-opioid receptor. Norbinaltorphimine dihydrochloride blocks κ-opioid receptor-mediated analgesic effects, and inhibits butorphanol-induced changes in κ-opioid receptor binding kinetics, desensitization and down-regulation. Norbinaltorphimine dihydrochloride suppresses specific opioid withdrawal symptoms, precipitates withdrawal behaviors in butorphanol-dependent rats, and serves as a molecular probe for studying κ-opioid receptor-agonist interactions. Norbinaltorphimine dihydrochloride is applicable to research related to neurological disorders such as pain.
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Dynorphin A
0 ImagesDynorphin A is an endogenous opioid peptide involved in inhibitory neurotransmission in the central nervous system (CNS). Dynorphin A is a highy potent kappa opioid receptor (KOR) agonist, and is also an agonist for other opioid receptors, such as mu (MOR) and delta (DOR). Dynorphin A can induce neuronal death, and can be used in the research of neurological disease.
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Naltrexone
0 ImagesNaltrexone is an orally active, long-acting opioid receptor (opioid receptor) antagonist. Naltrexone blocks the euphoric effects of exogenous opioids and reduces alcohol craving by blocking opioid receptors (μ, κ, and δ) as well as opioid growth factor receptors. Low doses of Naltrexone are used to relieve chronic pain, treat inflammatory diseases and inhibit tumor growth, while high doses or continuous administration exert pro-inflammatory or pro-proliferative effects. Naltrexone relieves intractable pruritus caused by psoriasis, atopic dermatitis and other conditions, and its combination with Bupropion (HY-B0403) inhibits food craving, thereby reducing body weight.
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Salvinorin B
0 ImagesSalvinorin B is a selective and brain-penetrant kappa opioid receptor (KOPr) agonist with an EC50 of 248 nM and Ki of 2.95 μM. Salvinorin B activates downstream signaling pathways by binding to KOPr, inhibits pain transmission and reduces inflammatory response. Salvinorin B can be used for the researches of inflammation, immunology and neurological disease, such as neuropathic pain, multiple sclerosis and anxiety.
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Mianserin hydrochloride
0 ImagesSynonyms: Org GB 94Mianserin hydrochloride (Org GB 94) is an orally active H1 receptor antagonist. Mianserin hydrochloride can activate κ-opioid receptor and octopamine receptor. Mianserin hydrochloride increases ERK1/2 and CREB phosphorylation, and antagonizes full κ-opioid agonist and Dynorphin A (HY-P1333)-induced MAPK phosphorylation. Mianserin hydrochloride modulates social and exploratory behaviour, raises electroconvulsive thresholds. Mianserin hydrochloride can be used for the research of neurological disease, such as depression and epilepsy.
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Mianserin
0 ImagesSynonyms: MianserineMianserin (Mianserine) is an orally active H1 receptor antagonist. Mianserin can activate κ-opioid receptor and octopamine receptor. Mianserin increases ERK1/2 and CREB phosphorylation, and antagonizes full κ-opioid agonist and Dynorphin A (HY-P1333)-induced MAPK phosphorylation. Mianserin modulates social and exploratory behaviour, raises electroconvulsive thresholds. Mianserin can be used for the research of neurological disease, such as depression and epilepsy.
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Sialorphin TFA
0 ImagesCat. No.: HY-P11642ASialorphin TFA is a neutral endopeptidase (NEP) and aminopeptidase N (APN) inhibitor that responds to androgen signals. Sialorphin TFA blocks the degradation of endogenous opioid peptides and interacts with μ-, δ-, κ-opioid receptors. Sialorphin TFA regulates the ERK/mTOR signaling pathway by inducing cell cycle arrest, enhancing ERK1/2 activity, and reducing the phosphorylation levels of mTOR, 4E-BP1, p70S6K; accordingly, Sialorphin TFA exhibits antiproliferative activity against colorectal cancer, glioma and prostate cancer cells without cytotoxicity. In addition, Sialorphin TFA also produces antinociceptive responses, regulates sexual behavior, relaxes corpus cavernosum smooth muscle, and alleviates experimental colitis. Sialorphin TFA is also a copper (II) ion-binding ligand. Sialorphin TFA has been used in mechanistic studies related to cancer, pain management and inflammatory bowel disease.
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Aticaprant
0 ImagesSynonyms: CERC-501; LY-2456302Aticaprant (CERC-501) is a potent and centrally-penetrant kappa opioid receptor antagonist with a Ki of 0.807 nM.
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Difelikefalin
0 ImagesSynonyms: CR-845; FE-202845Difelikefalin (CR-845; FE-202845) is an orally active peripherally acting kappa opioid receptor agonist. Difelikefalin reduces acute kidney injury, decreases oliguria, maintains urine flow, inhibits cytokine expression, and improves survival in endotoxemia after ischemia/reperfusion. Difelikefalin suppresses pruritus signals and exhibits neuromodulatory antipruritic activity. Difelikefalin can be used in research related to acute kidney injury, chronic kidney disease-associated pruritus, and atopic dermatitis.
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nor-Binaltorphimine
0 ImagesSynonyms: Norbinaltorphimine; NorBNInor-Binaltorphimine (Norbinaltorphimine; NorBNI) is a selective, long-acting competitive antagonist of the κ-opioid receptor. nor-Binaltorphimine blocks κ-opioid receptor-mediated analgesic effects, and inhibits butorphanol-induced changes in κ-opioid receptor binding kinetics, desensitization and down-regulation. nor-Binaltorphimine suppresses specific opioid withdrawal symptoms, precipitates withdrawal behaviors in butorphanol-dependent rats, and serves as a molecular probe for studying κ-opioid receptor-agonist interactions. nor-Binaltorphimine is applicable to research related to neurological disorders such as pain.
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U-69593
0 ImagesU-69593 is a potent and selective κ1-opioid receptor agonist. U-69593 attenuates addictive agent-induced behavioral sensitization in the rat. U-69593 reduces anxiety and enhances spontaneous alternation memory in mice. U-69593 reduces calcium-dependent dialysate levels of dopamine and glutamate in the ventral striatum.
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Navacaprant
0 ImagesSynonyms: BTRX-335140; CYM-53093Navacaprant (BTRX-335140) is a selective and orally active κ opioid receptor (KOR) antagonist, has antagonist activity for κOR, μOR and δOR with IC50 values of 0.8 nM, 110 nM, and 6500 nM, respectively. Navacaprant endows with favorable in vitro ADMET and in vivo pharmacokinetic profiles and medication-like duration of action in rats. Navacaprant distributes well into the CNS and can be used for the research of neuropathy.
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Porcine dynorphin A(1-13)
0 ImagesSynonyms: Dynorphin A Porcine Fragment 1-13Porcine dynorphin A (1-13) is a potent, endogenous κ opioid receptor agonist and is antinociceptive at physiological concentrations.
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Dynorphin A (1-8)
0 ImagesDynorphin A (1-8) is a ligand with preference for the κ-opioid receptor, and its IC50 value against human placental κ-opioid receptor is 330 nM. Dynorphin A (1-8) mediates neuroprotective effects by inhibiting oxidative stress, suppressing apoptosis, and competitively displacing the binding of κ partial agonists. Dynorphin A (1-8) is the dominant opioid peptide in human placental villi and tissue extracts; it undergoes rapid hydrolysis and can enter the central nervous system via intranasal administration. Dynorphin A (1-8) can be used in studies related to ischemic stroke.
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J-113397
0 ImagesJ-113397 is the first potent and selective nonpeptidyl ORL1 receptor antagonist (Ki: cloned human ORL1=1.8 nM) without any agonistic effects on other opioid receptors.
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Asimadoline hydrochloride
0 ImagesSynonyms: EMD-61753 hydrochlorideAsimadoline (EMD-61753) hydrochloride is an orally active, selective and peripherally active κ-opioid agonist with IC50s of 5.6 nM (guinea pig) and 1.2 nM (human recombinant). Asimadoline hydrochloride has low permeability across the blood brain barrier and has peripheral anti-inflammatory actions. Asimadoline hydrochloride ameliorates allodynia in diabetic rats and has the potential for irritable bowel syndrome (IBS).
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Loperamide
0 ImagesSynonyms: ADL 2-1294Loperamide (ADL 2-1294) is selective and orally active μ opioid receptor agonist with Ki valuess of 3, 48 and 1156 nM against μ, δ and κ opioid receptor, respectively. Loperamide produces antinociception and antihyperalgesia. Loperamide exhibits peripheral selectivity, enhancing fluid, electrolyte, and glucose absorption, reversing PGE2 (HY-101952)- and Cholera toxin (HY-P1446)-induced intestinal secretion, and reducing intestinal motility. Loperamide can be used for the researches of inflammatory pain and protracted diarrhoea.
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ICI-199441 hydrochloride
0 ImagesICI-199441 hydrochloride is a potent and selective κ-opioid receptor agonist with analgesic effects. ICI 199441 hydrochloride can improve heart resistance to ischemia/reperfusion.
