Differential actions of central alloxan upon opioid and nonopioid antinociception in rats: a further examination.
Previous work demonstrated that central pretreatment with alloxan significantly reduced antinociception induced by morphine and 2-deoxy-D-glucose (2DG), an opioid-mediated stressor, but not induced by continuous cold-water swims (CCWS), a nonopioid-mediated stressor. The alloxan-induced deficits in 2DG antinociception were ameliorated by coadministration of D-glucose (3 M, 3M-DG). The present study evaluated this relationship further by: a) examining whether central alloxan reduced morphine antinociception following either simultaneous 3M-DG and alloxan coadministration, alloxan followed 10 days later by 3M-DG and 3M-DG alone, and b) determining whether central alloxan pretreatment altered nonopioid antinociception induced by the muscarinic cholinergic agonist, pilocarpine. Morphine (2.5-5 mg/kg, SC) antinociception on the tail-flick and jump tests was significantly reduced by central alloxan. In contrast, simultaneous coadministration of 3M-DG and alloxan failed to alter morphine antinociception. This ameliorative effect of 3M-DG was not due to its ability to affect morphine antinociception, and was time-dependent in that delays in 3M-DG administration failed to affect the alloxan-induced deficit. Central alloxan pretreatment failed to alter pilocarpine antinociception on the tail-flick test, and increased pilocarpine antinociception on the jump test. That central alloxan reduced opioid (e.g., morphine and 2DG), but not nonopioid (e.g., CCWS, pilocarpine) forms of antinociception suggests a specific mode of action, possibly through disruptions of glucoprivic control mechanisms which is in keeping with the suggestion that opioid systems are sensitive to changes in central glucose function.
Department of Psychology and Neuropsychology, Queens College City University of New York, Flushing 11367.
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Lubin
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Kest
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Bodnar
D000496:Alloxan / Q000494:pharmacology*; D000818:Animals; D003847:Deoxyglucose / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology*; D010862:Pilocarpine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D010862:Pilocarpine; D009270:Naloxone; D000496:Alloxan; D009020:Morphine; D003847:Deoxyglucose