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Kreisman NR, Wooliscroft LB, Campbell CF, Dotiwala AK, Cox ML, Denson AC, Betancourt AM, Tomchuck SL. Preconditioning hippocampal slices with hypothermia promotes rapid tolerance to hypoxic depolarization and swelling: Mediation by erythropoietin. Brain Res 2019; 1726:146517. [PMID: 31634451 DOI: 10.1016/j.brainres.2019.146517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 08/06/2019] [Accepted: 10/17/2019] [Indexed: 12/26/2022]
Abstract
We suggested previously that hippocampal slices were protected from hypoxic depolarization and swelling by preincubating them at room temperature (Kreisman et al., 2000). We postulated that hypothermic preconditioning induced tolerance in our slices, which protected against hypoxic depolarization and swelling. Control hippocampal slices were incubated at 34-35 °C for two hours and the response to 10 min of severe hypoxia was compared to slices which were preconditioned for two hours at room temperature (22-23 °C) prior to warming to 34-35 °C. Recordings of the extracellular DC potential provided an index of tissue depolarization and changes in tissue light transmittance provided an index of swelling. Hypothermic preconditioning significantly reduced hypoxia-induced swelling, particularly in CA3 and the dentate inner blade. Since erythropoietin (EPO) had been shown to mediate hypoxic preconditioning, we tested whether EPO also mediated hypothermic preconditioning in our slices. Recombinant rat EPO (1-10 micromolar) mitigated hypoxia-induced swelling and depolarization in dentate inner blade of unconditioned slices in a dose-dependent manner. We also blocked the protective effects of hypothermic preconditioning on hypoxic depolarization and swelling in the inner blade of the dentate gyrus by administering soluble EPO receptor in the bath and treating slices with wortmannin to block phosphorylation of PI3 kinase, a critical step in the activation of the downstream neuroprotectant, Akt. These results suggest that EPO mediates tolerance to hypoxic depolarization and swelling induced by hypothermic preconditioning. They also emphasize that various preincubation protocols used in experiments with hippocampal slices may differentially affect basal electrophysiological and metabolic properties of those slices.
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Affiliation(s)
- Norman R Kreisman
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA 70112, United States; Tulane Brain Institute, New Orleans, LA 70118, United States.
| | | | - Carolyn F Campbell
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA 70112, United States; Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, United States
| | - Ary K Dotiwala
- Tulane Brain Institute, New Orleans, LA 70118, United States
| | - Michael L Cox
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA 70112, United States
| | - Aaron C Denson
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA 70112, United States
| | - Aline M Betancourt
- Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, United States
| | - Suzanne L Tomchuck
- Department of Microbiology & Immunology, Tulane University School of Medicine, New Orleans, LA 70112, United States
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Bischof GN, Ewers M, Franzmeier N, Grothe MJ, Hoenig M, Kocagoncu E, Neitzel J, Rowe JB, Strafella A, Drzezga A, van Eimeren T; MINC faculty. Connectomics and molecular imaging in neurodegeneration. Eur J Nucl Med Mol Imaging 2019; 46:2819-30. [PMID: 31292699 DOI: 10.1007/s00259-019-04394-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 06/04/2019] [Indexed: 10/26/2022]
Abstract
Our understanding on human neurodegenerative disease was previously limited to clinical data and inferences about the underlying pathology based on histopathological examination. Animal models and in vitro experiments have provided evidence for a cell-autonomous and a non-cell-autonomous mechanism for the accumulation of neuropathology. Combining modern neuroimaging tools to identify distinct neural networks (connectomics) with target-specific positron emission tomography (PET) tracers is an emerging and vibrant field of research with the potential to examine the contributions of cell-autonomous and non-cell-autonomous mechanisms to the spread of pathology. The evidence provided here suggests that both cell-autonomous and non-cell-autonomous processes relate to the observed in vivo characteristics of protein pathology and neurodegeneration across the disease spectrum. We propose a synergistic model of cell-autonomous and non-cell-autonomous accounts that integrates the most critical factors (i.e., protein strain, susceptible cell feature and connectome) contributing to the development of neuronal dysfunction and in turn produces the observed clinical phenotypes. We believe that a timely and longitudinal pursuit of such research programs will greatly advance our understanding of the complex mechanisms driving human neurodegenerative diseases.
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