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Hyperglycaemia: A Morphine‐Like Effect Produced By Naloxone
Author(s) -
Abouazra Ha,
Sharif Si
Publication year - 2001
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2001.03442.x
Subject(s) - (+) naloxone , yohimbine , antagonist , morphine , narcotic antagonist , opioid antagonist , endocrinology , medicine , agonist , opioid , cannula , competitive antagonist , chemistry , pharmacology , anesthesia , receptor , surgery
SUMMARY 1. Naloxone, which is often regarded as a pure opioid antagonist, produces effects similar to those produced by morphine. 2. In conscious rabbits implanted with an intracerebroventricular (i.c.v.) cannula, naloxone, whether given intravenously (1 mg/kg) or i.c.v. (1–100 μg), produced a significant rise in blood glucose levels. 3. Hyperglycaemia in response to naloxone (1 mg/kg, i.v., or 100 μg, i.c.v.) was not influenced by the selective α 1 ‐adrenoceptor antagonist WB‐4101 given either i.v. (50 μg) or i.c.v. (5 μg). 4. Hyperglycaemia in response to naloxone (1 mg/kg, i.v., or 100 μg, i.c.v.) was completely blocked by pretreatment with the α 2 ‐adrenoceptor antagonist yohimbine (1 mg/kg, i.v., or 100 μg, i.c.v.). However, hyperglycaemia to i.c.v. naloxone (100 μg) was not influenced by i.v. yohimbine (1 mg/kg). 5. Because naloxone behaves like morphine and produces hyperglycaemia in conscious rabbits, the drug may have an appreciable agonist activity and the hyperglycaemic response to naloxone is principally mediated via α 2 ‐ but not α 1 ‐adrenoceptors.