The mechanisms of such opiate-induced hyperalgesia and antinociceptive tolerance are unclear but a role for superoxide-derived peroxynitrite (ONOO-) and subsequent nitroxidative stress at the level of the spinal cord has been recently reported: morphine tolerance is associated with the overt production free radicals in a rodent model of opiate tolerance . Indeed, the development of morphine-induced hyperalgesia and antinociceptive tolerance was associated with increased activation of NADPH oxidase and superoxide release . In this study, oxidative stress is determined in mice using chronic administration of morphine to induce tolerance. Pretreatment with flavonoid fraction (1-10 mg/kg, i.p.) of Bergamot essential oil abolished morphine tolerance in a dose dependent manner together with free radicals formation. The development of tolerance is associated with increased oxidation of hydroethidine (HE) and malonildialdeide (MDA) formation in the spinal cord as evaluated by chromatographic analysis. Then, we developed a new HPLC method to determine, in homogenate CD-1 mice medulla, the reaction product of superoxide radical species and hydroethidine (HE) as a sensitive substrate of oxidation that is converted in ethidium (E+). LC/MS/ESI has been used to study the oxidative reaction. Moreover, MDA, as a measure of liperoxidation, is determined after derivatisation with dinitrophenylhydrazine (DNPH). We demonstrate that the phenolic components derived from Bergamot exerts antioxidant activities in vivo. These studies have unraveled a novel pathway in the nociceptive signaling cascade associated with opioid tolerance and support the potential clinical application of natural antioxidant in reinstating opioid efficacy.  Muscoli C, Cuzzocrea S, Ndengele M, Mollace V, Porreca F, Fabrizi F, Esposito E, Masini E, Matuschak G, Salvemini D. Therapeutic manipulation of peroxynitrite attenuates the development of opiate-induced antinociceptive tolerance in mice. J Clin Invest. 2007 Nov;117(11):3530-9.  Doyle T, Bryant L, Muscoli C, Cuzzocrea S, Esposito E, Chen Z, Salvemini D Spinal NADPH oxidase is a source of superoxide in the development of morphine-induced hyperalgesia and antinociceptive tolerance.Neurosci Lett. 2010 Oct 11;483(2):85-9.
|Titolo:||HPLC DETERMINATION OF BERGAMOT OIL EXTRACT ACTIVITY ON FREE RADICALS OVERT PRODUCTION IN A RODENT MODEL OF OPIATE TOLERANCE|
|Data di pubblicazione:||2013|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|