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Microdialysis delivery of morphine sulfate to rat pontine reticular formation (PRF) decreases PRF adenosine levels
Author(s) -
Nelson Ariana Marie,
Ignasiak Diane,
Baghdoyan Helen A.,
Lydic Ralph
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.945.11
Subject(s) - morphine , microdialysis , adenosine , medicine , isoflurane , anesthesia , opioid , pharmacology , nociception , (+) naloxone , central nervous system , receptor
Opioids disrupt sleep even in the absence of pain and sleep disruption intensifies the perception of pain. The essential role of opioids in pain management encourages development of adjunctive therapies that preserve analgesia while avoiding the unwanted side effect of sleep disruption. Delivery of adenosine agonists to the PRF promotes sleep and analgesia ( Anesthesiology 103: 1268, 2005) but no studies have determined whether opioids alter endogenous adenosine levels in the PRF. This study is testing the hypothesis that microdialysis delivery of morphine to rat PRF causes a concentration dependent decrease in PRF adenosine levels. During isoflurane anesthesia, the PRF of adult male Sprague‐Dawley rats (n=5) was dialyzed with Ringer.s solution containing 100 μM morphine. Compared to Ringer.s alone, morphine caused a significant (p<0.05) decrease in adenosine levels. Studies of additional rats (n=5) determined that co‐administration of naloxone (10 μM) prevented the decrease in adenosine caused by morphine. These results and ongoing concentration response studies support the interpretation that morphine decreases adenosine levels in a receptor‐dependent manner in the PRF, a brain region known to regulate sleep and nociception. Supported by the National Institute of Health grants HL57120, HL40881, MH45361, and the U. of Michigan Department of Anesthesiology and Medical School Office of Student Programs.