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Postsynaptic signaling via the [mu]-opioid receptor: responses of dorsal horn neurons to exogenous opioids and noxious stimulation.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Abbadie, Catherine Marek, Kenneth |
| Copyright Year | 2000 |
| Abstract | Although both pre- and postsynaptic mechanisms have been implicated in the analgesia produced by mu-opioids at the spinal cord, it is not known under what conditions these different controls come into play. Because the mu-opioid receptor (MOR) can be visualized in individual lamina II excitatory interneurons and internalizes into endosomes on ligand binding, we tested whether MOR internalization could be monitored and used to measure postsynaptic MOR signaling. To test whether endogenous opioids modulate these lamina II interneurons during noxious stimulation, we next assessed the magnitude of postsynaptic MOR internalization under a variety of nociceptive conditions. As observed in other systems, we show that MOR internalization in dorsal horn interneurons is demonstrated readily in response to opioid ligands. The MOR internalization is dose-dependent, with a similar dose-response to that observed for opioid-induced increases in potassium conductance. We demonstrate that MOR internalization in lamina II neurons correlates precisely with the extent of analgesia produced by intrathecal DAMGO. These results suggest that MOR internalization provides a good marker of MOR signaling in the spinal cord and that postsynaptic MORs on lamina II interneurons likely participate in the analgesia that is produced by exogenous opioids. We found, however, that noxious stimuli, under normal or inflammatory conditions, did not induce MOR internalization. Thus, endogenous enkephalins and endomorphins, thought to be released during noxious peripheral stimuli, do not modulate nociceptive messages via postsynaptic MORs on lamina II interneurons. We suggest that any endogenous opioids that are released by noxious stimuli target presynaptic MORs or delta-opioid receptors. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.jneurosci.org/content/20/23/8578.full.pdf |
| Alternate Webpage(s) | http://www.jneurosci.org/content/jneuro/20/23/8578.full.pdf |
| PubMed reference number | 11102461v1 |
| Volume Number | 20 |
| Issue Number | 23 |
| Journal | The Journal of neuroscience : the official journal of the Society for Neuroscience |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Endogenous Opiates Endosomes Enkephalins External granular layer of cerebral cortex IGF2R protein, human Interneurons Ligands Opioid Receptor Opioids Posterior Horn Cells Potassium Receptors, Opioid, delta Receptors, Opioid, mu Structure of posterior gray horn of spinal cord Substantia Gelatinosa message |
| Content Type | Text |
| Resource Type | Article |
