NOC/oFQ PKC-dependent superoxide generation contributes to hypoxic-ischemic impairment of NMDA cerebrovasodilation.
This study determined whether nociceptin/orphanin FQ (NOC/oFQ) generates superoxide anion (O(2)(-)) in a protein kinase C (PKC)-dependent manner and whether such production contributes to hypoxic-ischemic (H-I) impairment of N-methyl-D-aspartate (NMDA)-induced pial artery dilation in newborn pigs equipped with closed cranial windows. Superoxide dismutase (SOD)-inhibitable nitroblue tetrazolium (NBT) reduction was an index of O(2)(-) generation. Under non-H-I conditions, topical NOC/oFQ (10(-10) M, concentration present in cerebrospinal fluid after I or H-I) increased SOD-inhibitable NBT reduction from 1 +/- 1 to 20 +/- 3 pmol/mm(2). PKC inhibitors staurosporine and chelerythrine (10(-7) M) blunted NBT reduction (1 +/- 1 to 7 +/- 2 pmol/mm(2) for chelerythrine), whereas the NOC/oFQ receptor antagonist [F/G]NOC/oFQ (1-13)-NH(2) (10(-6) M) blocked NBT reduction. [F/G]NOC/oFQ(1-13)-NH(2) and staurosporine also blunted the NBT reduction observed after I or H-I. NMDA (10(-8), 10(-6) M)-induced pial artery dilation was reversed to vasoconstriction after H-I. The NOC/oFQ antagonist staurosporine and free radical scavengers partially prevented this impaired dilation (sham: 9 +/- 1 and 16 +/- 1; H-I: -5 and -10 +/- 1; H-I staurosporine pretreated: 3 +/- 1 and 6 +/- 1%). These data show that NOC/oFQ increased O(2)(-) production in a PKC-dependent manner and contributed to this production after insult and that NOC/oFQ contributed to impaired NMDA-induced pial artery dilation after H-I, suggesting, therefore, that PKC-dependent O(2)(-) generation by NOC/oFQ links NOC/oFQ release to impaired NMDA dilation after H-I.
Armstead
W M
WM
Departments of Anesthesia and Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. armsteaw@mail.med.upenn.edu
D000470:Alkaloids; D000818:Animals; D000831:Animals, Newborn; D000838:Anions / Q000378:metabolism; D053119:Benzophenanthridines; D002536:Cerebral Arteries / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism*; D007202:Indicators and Reagents; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology*; D009580:Nitroblue Tetrazolium; D018847:Opioid Peptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D010617:Phenanthridines / Q000494:pharmacology; D010841:Pia Mater / Q000098:blood supply / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013552:Swine; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*; D000097629:Nociceptin
D000470:Alkaloids; D000838:Anions; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D005609:Free Radicals; D007202:Indicators and Reagents; D016202:N-Methylaspartate; D009580:Nitroblue Tetrazolium; D018847:Opioid Peptides; D010446:Peptide Fragments; D010617:Phenanthridines; D011493:Protein Kinase C; D019311:Staurosporine; D013482:Superoxide Dismutase; D013481:Superoxides; D014665:Vasodilator Agents; D000097629:Nociceptin; C114149:nociceptin (1-13)-NH2, Phe(1)-psi(CH2-NH)-Gly(2)-; C016299:chelerythrine