Changes in brain oxygen and glucose induced by oxycodone: Relationships with brain temperature and peripheral vascular tone. (1st May 2018)

• Record Type: Journal Article
• Authors: Solis, Ernesto; Afzal, Anum; Kiyatkin, Eugene A.
• Is Part Of: Neuropharmacology. Volume 133(2018)
• Page Start: 481
• Page End: 490
• Publication Date: 2018-05-01
• Subjects: Opiates -- Brain and body hyperthermia -- Metabolic brain activation -- Vasoconstriction -- Vasodilation -- Nucleus accumbens -- Rats; Neuropsychopharmacology -- Periodicals; Autonomic Agents -- Periodicals; Neuropsychopharmacologie -- Périodiques; Neuropsychopharmacology; Periodicals; Electronic journals; 615.78
• DOI: 10.1016/j.neuropharm.2018.02.017
• Languages: English
• ISSNs: 0028-3908

Abstract

Abstract: Oxycodone is a semi-synthetic opioid drug that is used to alleviate acute and chronic pain. However, oxycodone is often abused and, when taken at high doses, can induce powerful CNS depression that manifests in respiratory abnormalities, hypotension, coma, and death. Here, we employed several techniques to examine the effects of intravenous oxycodone at a wide range of doses on various metabolism-related parameters in awake, freely-moving rats. High-speed amperometry was used to assess how oxycodone affects oxygen and glucose levels in the nucleus accumbens (NAc). These measurements were supplemented by recordings of locomotor activity and temperature in the NAc, temporal muscle, and skin. At low doses, which are known to maintain self-administration behavior (0.15–0.3 mg/kg), oxycodone transiently decreased locomotor activity, induced modest brain and body hyperthermia, and monotonically increased NAc oxygen and glucose levels. While locomotor inhibition became stronger with higher oxycodone doses (0.6–1.2 mg/kg), NAc oxygen and glucose transiently decreased and subsequently increased. High-dose oxycodone induced similar biphasic down-up changes in brain and body temperature, with the initial decreases followed by increases. While cerebral vasodilation induced by neural activation appears to be the underlying mechanism for the correlative increases in brain oxygen and glucose levels, respiratory depression and the subsequent drop in blood oxygen likely mediate the brain hypoxia induced by large-dose oxycodone injections. The initial inhibitory effects induced by large-dose oxycodone injections could be attributed to rapid and profound CNS depression—the most dangerous health complication linked to opioid overdose in humans. Graphical abstract: Highlights: At low doses, iv oxycodone increases NAc levels of oxygen and glucose. These effects likely result from cerebral vasodilation due to neural activation. At low doses, iv oxycodone induces modest brain and body hyperthermia. This effect results primarily from peripheral vasoconstriction. At higher doses, oxycodone decreases NAc oxygen levels due to respiratory depression.