{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,4]],"date-time":"2026-10-04T09:46:32Z","timestamp":1791107192389,"version":"4.1.0"},"reference-count":38,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2009,1,29]],"date-time":"2009-01-29T00:00:00Z","timestamp":1233187200000},"content-version":"vor","delay-in-days":2981,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["bpspubs.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["British J Pharmacology"],"published-print":{"date-parts":[[2000,12]]},"abstract":"<jats:p>\n<jats:list list-type=\"explicit-label\">\n<jats:list-item><jats:p>The pharmacological properties of the active morphine metabolite, morphine\u20106\u03b2\u2010D\u2010glucuronide (M6G), and the parent compound were compared in rat locus coeruleus neurons by electrophysiological recording in brain slices.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>M6G and morphine activated potassium currents in voltage clamped neurons, which were blocked by the opioid receptor antagonist naloxone.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>Both M6G and morphine behaved as partial agonists that produced maximal responses smaller than the system maximum, which was measured using [Met<jats:sup>5<\/jats:sup>]\u2010enkephalin. M6G produced a larger maximal response (78%) than morphine (62%), which we estimated was due to a 2\u20134 fold difference in the relative efficacy of the agonists.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>3\u2010O\u2010methoxynaltrexone, which has been reported to behave as a selective antagonist of a M6G preferring receptor, was equally effective at blocking currents produced by M6G and the selective mu\u2010opioid receptor agonist DAMGO.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>M6G currents were occluded by a prior application of morphine, and were reduced when mu\u2010opioid receptors were desensitized by using [Met<jats:sup>5<\/jats:sup>]\u2010enkephalin.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>Morphine\u20103\u03b2\u2010D\u2010glucuronide did not affect action potential firing or membrane currents in locus coeruleus neurons and had no effect on currents produced by M6G.<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p>These results show that the relative efficacy of M6G is higher than morphine in locus coeruleus neurons, contrary to what has been shown using mu\u2010opioid receptors expressed in cell clones.<\/jats:p><\/jats:list-item>\n<\/jats:list>\n<\/jats:p><jats:p><jats:italic>British Journal of Pharmacology<\/jats:italic> (2000) <jats:bold>131<\/jats:bold>, 1422\u20131428; doi:<jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"doi\" xlink:href=\"10.1038\/sj.bjp.0703697\">10.1038\/sj.bjp.0703697<\/jats:ext-link><\/jats:p>","DOI":"10.1038\/sj.bjp.0703697","type":"journal-article","created":{"date-parts":[[2005,1,28]],"date-time":"2005-01-28T21:00:44Z","timestamp":1106946044000},"page":"1422-1428","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":27,"title":["Morphine\u20106<i>\u03b2<\/i>\u2010glucuronide has a higher efficacy than morphine as a mu\u2010opioid receptor agonist in the rat locus coeruleus"],"prefix":"10.1111","volume":"131","author":[{"given":"Peregrine B","family":"Osborne","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Billy","family":"Chieng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"MacDonald J","family":"Christie","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2009,1,29]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/0024-3205(91)90453-I"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/0024-3205(88)90479-1"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1098\/rspb.1983.0093"},{"key":"e_1_2_7_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0014-5793(97)00710-2"},{"key":"e_1_2_7_6_1","first-page":"1291","article-title":"3H\u2010morphine\u20106beta\u2010glucuronide binding in brain membranes and an MOR\u20101\u2010transfected cell line","volume":"282","author":"BROWN G.P.","year":"1997","journal-title":"J. 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