Antibodies for Opioid Receptor Research

Opioid peptides are endogenous neuromodulators that play a major role in nociception by interacting with several membrane receptors. Molecular cloning techniques have characterized the nucleotide sequence of several distinct opioid receptors, including the δ-, κ- and μ-opioid receptors.1 The cloned receptors are highly homologous (65%), differing only at the N- and C-termini and at the extracelluar loops that confer binding specificity.2 All three receptors interact with heterotrimeric G proteins.3

δ-Opioid receptors (DOR) are located postsynaptically on pallidostriatal feedback neurons.4 DORs also modulate nociception presynaptically in the periaqueductal gray where immunolabeling of DOR has been shown to be intracellular and often associated with large dense-core vesicles.5 Additionally, receptor autoradiographic investigations have localized DORs to the external plexiform layer of the olfactory bulb, the nucleus accumbens, several layers of the cerebral cortex and several nuclei of the amygdala.6

The κ-opioid receptor (KOR)7 is primarily responsible for mediating the effects of the products of preprodynorphin and possibly preproenkephalin.8 Localization of the KOR is primarily postsynaptic. Immunolocalization of KOR on sections of rat and guinea-pig brain demonstrated prominent staining in the ventral forebrain, hypothalamus, thalamus, posterior pituitary and midbrain.8

Of the three opioid receptors, the μ-opioid receptor (MOR) shows the highest affinity for morphine. Activation of MORs inhibits GABA-containing interneurons, resulting in a net excitatory effect in the hippocampus.9 Localization of MORs is both pre- and post-synaptic and almost exclusively on GABAergic interneurons. MORs are widely distributed in regions throughout the brain and spinal cord including laminae I and II of the medullary and spinal dorsal horns, the striatum, the optic tract and the locus coeruleus.10




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  3. Childers, S.R. Life Sci., 48, 1991-2003 (1991).
  4. Olive, M.F. et al. J. Neurosci.17, 7471-7479 (1997).
  5. Commons, K.G. et al. J. Comp. Neurol.430, 200-208 (2001).
  6. Quock, R.M. et al. Pharmacol. Rev.51, 503-532 (1999).
  7. Yakovlev, A.G. et al. J. Biol. Chem.270, 6421-6424 (1995).
  8. Arvidsson, U. et al. Proc. Natl. Acad. Sci. USA92, 5062-5066 (1995).
  9. Drake, C.T, Milner, T.A. Brain Res.849, 203-215 (1999).
  10. Ding, Y.Q. et al. J. Comp. Neurol.367, 375-402 (1996).


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