title: Epsilon protein kinase C mediated ischemic tolerance requires activation of the extracellular regulated kinase pathway in the organotypic hippocampal slice.
abstract: Ischemic preconditioning (IPC) promotes brain tolerance against subsequent ischemic insults. Using the organotypic hippocampal slice culture, we conducted the present study to investigate (1) the role of adenosine A1 receptor (A1AR) activation in IPC induction, (2) whether epsilon protein kinase C (epsilonPKC) activation after IPC is mediated by the phosphoinositol pathway, and (3) whether epsilonPKC protection is mediated by the extracellular signal-regulated kinase (ERK) pathway. Our results demonstrate that activation of A1AR emulated IPC, whereas blockade of the A1AR during IPC diminished neuroprotection. The neuroprotection promoted by the A1AR was also reduced by the epsilonPKC antagonist. To determine whether epsilonPKC activation in IPC and A1AR preconditioning is mediated by activation of the phosphoinositol pathway, we incubated slices undergoing IPC or adenosine treatment with a phosphoinositol phospholipase C inhibitor. In both cases, preconditioning neuroprotection was significantly attenuated. To further characterize the subsequent signal transduction pathway that ensues after epsilonPKC activation, mitogen-activated protein kinase kinase was blocked during IPC and pharmacologic preconditioning (PPC) (with epsilonPKC, NMDA, or A1AR agonists). This treatment significantly attenuated IPC- and PPC-induced neuroprotection. In conclusion, we demonstrate that epsilonPKC activation after IPC/PPC is essential for neuroprotection against oxygen/glucose deprivation in organotypic slice cultures and that the ERK pathway is downstream to epsilonPKC.
authors.affiliation: Cerebral Vascular Disease Research Center, Department of Neurology and Neuroscience, University of Miami School of Medicine, Miami, Florida, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Lange-Asschenfeldt
authors.forename: Ami P
authors.initials: AP
authors.lastname: Raval
authors.forename: Kunjan R
authors.initials: KR
authors.lastname: Dave
authors.forename: Daria
authors.initials: D
authors.lastname: Mochly-Rosen
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Sick
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Pérez-Pinzón
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002545:Brain Ischemia / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D066298:In Vitro Techniques; D019194:Ischemic Preconditioning; D007527:Isoenzymes / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000378:metabolism*; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D007527:Isoenzymes; D043682:Receptor, Adenosine A1; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; C497257:Prkce protein, rat; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one