Journal article
Behavioral Consequences of Delta-Opioid Receptor Activation in the Periaqueductal Gray of Morphine Tolerant Rats
Neural plasticity, Vol.2009, pp.1-7
2009
Handle:
https://hdl.handle.net/2376/108091
PMCID: PMC2650089
PMID: 19266049
Abstract
Chronic morphine administration shifts delta-opioid receptors (DORs) from the cytoplasm to the plasma membrane. Given that microinjection of morphine into the PAG produces antinociception, it is hypothesized that the movement of DORs to the membrane will allow antinociception to the DOR agonist deltorphin II as a way to compensate for morphine tolerance. Tolerance was induced by twice daily injections of morphine (5, 10, or 20 mg/kg, subcutaneous) for 3.5 days. Microinjection of deltorphin into the vPAG 6 hours after the last morphine injection produced a mild antinociception that did not vary in a consistent manner across morphine pretreatment doses or nociceptive tests. In contrast, deltorphin caused a decrease in activity in morphine tolerant rats that was associated with lying in the cage. The decrease in activity and change in behavior indicate that chronic morphine administration alters DORs in the vPAG. However, activation of these receptors does not appear to compensate for the decrease in antinociception caused by morphine tolerance.
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Details
- Title
- Behavioral Consequences of Delta-Opioid Receptor Activation in the Periaqueductal Gray of Morphine Tolerant Rats
- Creators
- Michael M Morgan - Department of Psychology, Washington State University Vancouver, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686, USAMichelle D Ashley - Department of Psychology, Washington State University Vancouver, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686, USASusan L Ingram - Department of Psychology, Washington State University Vancouver, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686, USAMacDonald J Christie - Brain and Mind Research Institute, The University of Sydney, NSW 2006, Australia
- Publication Details
- Neural plasticity, Vol.2009, pp.1-7
- Academic Unit
- Psychology, Department of
- Identifiers
- 99900547140601842
- Language
- English
- Resource Type
- Journal article