Opioid Receptors

Opioid receptors are currently classified into three groups, κ, δ and μ receptors. Subtypes within each group have been suggested including μ1, μ2, δ1, δ2, κ1, κ2, and κ3. An opioid-like receptor with a high degree of homology to μ, δ and κ-opioid receptors has been cloned and termed the orphan opioid receptor (NOP, ORL1). This receptor has a distinct pharmacological profile from the classical opioid receptors and an endogenous ligand, nociceptin (orphanin FQ) has been identified.

Targets
Literature
Receptor Data

Literature for Opioid Receptors

GPCR

GPCR Product Listing

A collection of over 450 products for G protein-coupled receptors, the listing includes research tools for the study of:

  • Rhodopsin-like Receptors
  • Secretin-like Receptors
  • Glutamate Receptors
  • Frizzled Receptors
  • GPCR Signaling
Pain

Pain Research Product Guide

A collection of over 250 products for pain research, the guide includes research tools for the study of:

  • Nociception
  • Ion Channels
  • G-Protein-Coupled Receptors
  • Intracellular Signaling
Peptides Involved in Appetite Modulation

Peptides Involved in Appetite Modulation Scientific Review

Written by Sonia Tucci, Lynsay Kobelis and Tim Kirkham, this review provides a synopsis of the increasing number of peptides that have been implicated in appetite regulation and energy homeostasis; putative roles of the major peptides are outlined and compounds available from Tocris are listed.

Addiction

Addiction Poster

The key feature of drug addiction is the inability to stop using a drug despite clear evidence of harm. This poster describes the brain circuits associated with addiction, and provides an overview of the main classes of addictive drugs and the neurotransmitter systems that they target.

Pain

Pain Poster

Peripheral sensitization is the reduction in the threshold of excitability of sensory neurons that results in an augmented response to a given external stimulus. This poster outlines the excitatory and inhibitory signaling pathways involved in modulation of peripheral sensitization. The role of ion channels, GPCRs, neurotrophins, and cytokines in sensory neurons are also described.

Opioid Receptor Data

Receptor Subtype μ (MOP, OP3) δ (DOP, OP1) κ (KOP, OP2) NOP (ORL1, OP4)
G protein Gi/o Gi/o Gi/o Gi/o
Transduction Mechanism Activation of inwardly rectifying K+ channels, inhibition of Ca2+ channels, inhibition of adenylyl cyclase
Localization in CNS Anterior cingulate cortex, neocortex, amygdala, hippocampus, ventral dentate gyrus, presubiculum, nucleus accumbens, caudate putamen, thalamus, habenula, interpeduncular nucleus, pars compacta of the substantia nigra, superior and inferior colliculi, raphe nuclei Medial habenula, hypothalamus, pons, medulla, dorsal root ganglion, caudate putamen, medial habenula, tegmentum, trigeminal nucleus Claustrum, endopiriform nucleus, caudate putamen, nucleus accumbens, midline nuclear group of the thalamus, superficial grey layer of the superior colliculus, central grey, caudate putamen, nucleus accumbens, amygdala, thalamus, interpeduncular nuclei Cortex, olfactory bulb, suprachiasmatic nucleus, amygdala, nucleus accumbens, thalamic nuclei, hypothalamus, hippocampus, septum, superior colliculus
Likely Physiological Roles Respiration, cardiovascular functions, feeding, learning and memory, intestinal transit, locomotor activity, thermoregulation, hormone secretion, immune functions Analgesia, motor integration, gastrointestinal motility, olfaction, respiration, cognitive function, mood driven behavior Regulation of nociception, diuresis, feeding, neuroendocrine secretions Motor and balance control, reinforcement and reward, nociception, the stress response, sexual behavior, aggression, autonomic control of physiological processes
Key Selective Agonists Endomorphin-1 (1055)
Endomorphin-2 (1056)
DAMGO (1171)
SNC 80 (0764)
SB 205607 (0921)
DPDPE (1431)
(±)-U-50488 (0495)
BRL 52537 (0699)
Dynorphin A (3195)
Nociceptin (0910)
MCOPPB (3763) SCH 221510 (3240)
Key Selective Antagonists β-Funaltrexamine (0926)
CTOP (1578)
Cyprodime (2601)
Naltrindole (0740)
Naltriben (0892)
BNTX maleate (0899)
nor-Binaltorphimine (0347)
DIPPA (0794)
GNTI (1282)
UFP-101 (1552)
(±)-J 113397 (2598)
JTC 801 (2481)

References

Dhawan et al (1996) International union of pharmacology. XII. Classification of Opioid Receptors. Pharmacol Rev. 48 567.
Cox et al (2009) Opioid receptors, introductory chapter. Last modified on 13/10/2009. Accessed on 27/02/2013. IUPHAR database (IUPHAR-DB).