Hyperglycaemia: A Morphine-Like Effect Produced By Naloxone

Authors: Abouazra H.; Sharif S.

Source: Clinical and Experimental Pharmacology and Physiology, Volume 28, Number 4, April 2001 , pp. 300-305(6)

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Abstract:

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 g), produced a significant rise in blood glucose levels.

3. Hyperglycaemia in response to naloxone (1 mg/kg, i.v., or 100 g, i.c.v.) was not influenced by the selective alpha ₁-adrenoceptor antagonist WB-4101 given either i.v. (50 g) or i.c.v. (5 g).

4. Hyperglycaemia in response to naloxone (1 mg/kg, i.v., or 100 g, i.c.v.) was completely blocked by pretreatment with the alpha ₂-adrenoceptor antagonist yohimbine (1 mg/kg, i.v., or 100 g, i.c.v.). However, hyperglycaemia to i.c.v. naloxone (100 g) 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 alpha ₂- but not alpha ₁-adrenoceptors.

Keywords: alpha -adrenoceptor; blood glucose level; hyperglycaemia; naloxone; rabbits; WB-4101; yohimbine

Language: English

Document Type: Research article

Publication date: 2001-04-01