Modulation of brainstem opiate analgesia in the rat by σ1 receptors: A microinjection study Journal Article
| Authors: | Mei, J.; Pasternak, G. W. |
| Article Title: | Modulation of brainstem opiate analgesia in the rat by σ1 receptors: A microinjection study |
| Abstract: | σ1 Receptors have been implicated in the modulation of opioid analgesia. In the current study, we examined the role of σ1 systems in the periaqueductal gray (PAG), the rostroventral medulla (RVM), and the locus coeruleus (LC) of the rat, regions previously shown to be sensitive to morphine. Morphine was a potent analgesic in all three regions. Coadministration of the σ1 agonist (+)-pentazocine diminished the analgesic actions of morphine in all three regions, although the PAG was far less sensitive than the other two regions. Blockade of the σ1 receptors with haloperidol in the RVM markedly enhanced the analgesic actions of coadministered morphine, implying a tonic activity of the σ1 system in this region. This effect was mimicked by down-regulation of RVM σ1 receptors using an antisense approach. However, no tonic σ1 activity was observed in either the LC or the PAG. The RVM also was important in modulating analgesia elicited from morphine microinjected into the PAG. The analgesic actions of morphine given into the PAG could be attenuated by (+)-pentazocine placed into the RVM, whereas haloperidol in the RVM enhanced PAG morphine analgesia. These studies illustrate the pharmacological importance of σ1 receptors in the brainstem modulation of opioid analgesia. Copyright © 2007 by The American Society for Pharmacology and Experimental Therapeutics. |
| Keywords: | controlled study; nonhuman; animals; haloperidol; animal experiment; neuromodulation; locus ceruleus; rat; down regulation; rats; receptor blocking; rats, sprague-dawley; morphine; analgesics, opioid; analgesia; brain stem; microinjections; analgesic activity; microinjection; pentazocine; sigma 1 opiate receptor; receptors, sigma; periaqueductal gray matter; locus coeruleus; periaqueductal gray |
| Journal Title: | Journal of Pharmacology and Experimental Therapeutics |
| Volume: | 322 |
| Issue: | 3 |
| ISSN: | 0022-3565 |
| Publisher: | American Society for Pharmacology and Experimental Therapeutics |
| Date Published: | 2007-09-01 |
| Start Page: | 1278 |
| End Page: | 1285 |
| Language: | English |
| DOI: | 10.1124/jpet.107.121137 |
| PUBMED: | 17545312 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 12" - "Export Date: 17 November 2011" - "CODEN: JPETA" - "Source: Scopus" |
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