Antagonism of antinociception in mice by glucose and fructose: comparison of subcutaneous and intrathecal morphine.
Determination of the ED50s of glucose and fructose, administered i.p., for antagonizing the antinociceptive action of morphine (4 mg/kg s.c. or 0.5 micrograms i.t.) and determination of the ED50s for i.t. morphine after i.p. pretreatment with saline, glucose (5 g/kg) or fructose (5 g/kg) in the mouse tail-flick test indicated that fructose was more potent than glucose in antagonizing antinociception after either route or morphine administration. It is concluded that the antagonism of morphine-induced antinociception by glucose and fructose is due to a direct effect of these sugars or their metabolic products within the central nervous system.
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Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0001.
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D000700:Analgesics / Q000037:antagonists & inhibitors*; D000818:Animals; D005632:Fructose / Q000008:administration & dosage / Q000494:pharmacology*; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D007278:Injections, Spinal; D007279:Injections, Subcutaneous; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000037:antagonists & inhibitors*; D010147:Pain Measurement
D000700:Analgesics; D005632:Fructose; D009020:Morphine; D005947:Glucose