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Hough LB, Nalwalk JW, Ding X, Scheer N. Opioid Analgesia in P450 Gene Cluster Knockout Mice: A Search for Analgesia-Relevant Isoforms. Drug Metab Dispos 2015; 43:1326-30. [PMID: 26109562 DOI: 10.1124/dmd.115.065490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 06/24/2015] [Indexed: 01/10/2023] Open
Abstract
Cytochrome P450 monooxygenases (P450s), which are well-known drug-metabolizing enzymes, are thought to play a signal transduction role in µ opioid analgesia and may serve as high-affinity (3)H-cimetidine ((3)HCIM) binding sites in the brain. (3)HCIM binding sites may also be related to opioid or nonopioid analgesia. However, of the more than 100 murine P450 enzymes, the specific isoform(s) responsible for either function have not been identified. Presently, three lines of constitutive P450 gene cluster knockout (KO) mice with full-length deletions of 14 Cyp2c, 9 Cyp2d, and 7 Cyp3a genes were studied for deficiencies in (3)HCIM binding and for opioid analgesia. Liver and brain homogenates from all three genotypes showed normal (3)HCIM binding values, indicating that gene products of Cyp2d, Cyp3a, and Cyp2c are not (3)HCIM-binding proteins. Cyp2d KO and Cyp3a KO mice showed normal antinociceptive responses to a moderate systemic dose of morphine (20 mg/kg, s.c.), thereby excluding 16 P450 isoforms as mediators of opioid analgesia. In contrast, Cyp2c KO mice showed a 41% reduction in analgesic responses following systemically (s.c.) administered morphine. However, the significance of brain Cyp2c gene products in opioid analgesia is uncertain because little or no analgesic deficits were noted in Cyp2c KO mice following intracerebroventricular or intrathecalmorphine administration, respectively. These results show that the gene products of Cyp2d and Cyp3a do not contribute to µ opioid analgesia in the central nervous system. A possible role for Cyp2c gene products in opioid analgesia requires further consideration.
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Affiliation(s)
- Lindsay B Hough
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York (L.B.H., J.W.N.); College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.); and Taconic Biosciences GmbH, Cologne, Germany (N.S.)
| | - Julia W Nalwalk
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York (L.B.H., J.W.N.); College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.); and Taconic Biosciences GmbH, Cologne, Germany (N.S.)
| | - Xinxin Ding
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York (L.B.H., J.W.N.); College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.); and Taconic Biosciences GmbH, Cologne, Germany (N.S.)
| | - Nico Scheer
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York (L.B.H., J.W.N.); College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York (X.D.); and Taconic Biosciences GmbH, Cologne, Germany (N.S.)
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Lafifi I, Khatmi D. Theoretical Investigation of the Intramolecular H-Bonding on Tautomerism. ADVANCES IN QUANTUM CHEMISTRY 2014. [DOI: 10.1016/b978-0-12-800536-1.00013-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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