The dose-response relation and tolerance pattern of morphine in the formalin test, an animal model of tonic pain, were shown to be similar to those observed clinically in man. Tolerance was negligible and there was a ceiling to amount of analgesia once the acute depressant effects of morphine abate. In contrast, in the tail-flick test marked tolerance was seen in which the dose-response curve was shifted towards higher doses. These differences suggest that the underlying neural mechanisms involved in morphine analgesia in the formalin and tail-flick tests are different. In confirmation, brainstem lesions in the raphe magnus and the caudal periventricular gray attenuated analgesia in the tail-flick test but had no effect on analgesia in the formalin test. Lesions of the median raphe and the pontine reticular formation potentiated the effects of morphine in the formalin test but not in the tail-flick test. No brainstem lesion site was found that attenuated analgesia in the formalin test.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68527 |
| Date | January 1980 |
| Creators | Abbott, Frances V. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Psychology) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000112511, proquestno: AAINK51834, Theses scanned by UMI/ProQuest. |
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