| Metamizol, a non-opioid analgesic, acts via endocannabinoids in the PAG-RVM axis during inflammation in rats. | |
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MedLine Citation:
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PMID: 22337336 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The most commonly used drugs against pain act by inhibiting the cyclooxygenases (COXs). Metamizol (dipyrone) inhibits the COXs and is widely used in Europe and Latin America as a non-opioid analgesic. One target of metamizol and other non-opioid analgesics is the periaqueductal grey matter (PAG), where they trigger descending inhibition of spinal nociceptive transmission. Also, cannabinoids exert an analgesic action at several structures in the peripheral and central nervous system, including the PAG. The present study investigates whether the antinociceptive action of metamizol in the lateral-ventrolateral (LVL) PAG during inflammation is related to endocannabinoids. In anaesthetized rats, unitary action potentials were recorded from spinal nociceptive neurons with receptive fields in the ipsilateral hind paw. Inflammation of the paw induced neuronal hyperexcitability, which was attenuated by intra-LVL-PAG microinjection of metamizol either at the beginning of inflammation or when hyperexcitability was fully established. In both cases, the antinociceptive effect of metamizol was reduced by a microinjection of AM251, an antagonist at the CB1 cannabinoid receptor, either into the LVL-PAG or into the rostral ventromedial medulla (RVM). The RVM is a downstream structure that funnels PAG-derived descending inhibition into the spinal cord. These results show that endocannabinoids and their CB1 receptor (1) contribute at the LVL-PAG to the antinociceptive effects of metamizol, and possibly other non-opioid analgesics; and (2) participate in the PAG-derived activation of RVM descending antinociceptive influences. |
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Authors:
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W Escobar; K Ramirez; C Avila; R Limongi; H Vanegas; E Vazquez |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-12-19 |
Journal Detail:
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Title: European journal of pain (London, England) Volume: - ISSN: 1532-2149 ISO Abbreviation: - Publication Date: 2011 Dec |
Date Detail:
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Created Date: 2012-2-16 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9801774 Medline TA: Eur J Pain Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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© 2011 European Federation of International Association for the Study of Pain Chapters. |
Affiliation:
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Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 20632, Caracas, 1020-A, Venezuela. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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