title: 'Mild mitochondrial uncoupling' induced protection against neuronal excitotoxicity requires AMPK activity.
abstract: The preconditioning response conferred by a mild uncoupling of the mitochondrial membrane potential (Δψ(m)) has been attributed to altered reactive oxygen species (ROS) production and mitochondrial Ca(2+) uptake within the cells. Here we have explored if altered cellular energetics in response to a mild mitochondrial uncoupling stimulus may also contribute to the protection. The addition of 100 nM FCCP for 30 min to cerebellar granule neurons (CGNs) induced a transient depolarization of the Δψ(m), that was sufficient to significantly reduce CGN vulnerability to the excitotoxic stimulus, glutamate. On investigation, the mild mitochondrial 'uncoupling' stimulus resulted in a significant increase in the plasma membrane levels of the glucose transporter isoform 3, with a hyperpolarisation of Δψ(m) and increased cellular ATP levels also evident following the washout of FCCP. Furthermore, the phosphorylation state of AMP-activated protein kinase (AMPK) (Thr 172) was increased within 5 min of the uncoupling stimulus and elevated up to 1h after washout. Significantly, the physiological changes and protection evident after the mild uncoupling stimulus were lost in CGNs when AMPK activity was inhibited. This study identifies an additional mechanism through which protection is mediated upon mild mitochondrial uncoupling: it implicates increased AMPK signalling and an adaptive shift in energy metabolism as mediators of the preconditioning response associated with FCCP-induced mild mitochondrial uncoupling.
authors.affiliation: Department of Physiology and Medical Physics, Centre for the Study of Neurological Disorders, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.
authors.forename: Petronela
authors.initials: P
authors.lastname: Weisová
authors.forename: Ujval
authors.initials: U
authors.lastname: Anilkumar
authors.forename: Caitriona
authors.initials: C
authors.lastname: Ryan
authors.forename: Caoimhín G
authors.initials: CG
authors.lastname: Concannon
authors.forename: Jochen H M
authors.initials: JH
authors.lastname: Prehn
authors.forename: Manus W
authors.initials: MW
authors.lastname: Ward
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology; D019610:Cytoprotection / Q000187:drug effects*; D004734:Energy Metabolism; D004789:Enzyme Activation / Q000187:drug effects; D018698:Glutamic Acid / Q000633:toxicity; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D009498:Neurotoxins / Q000633:toxicity*; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D009498:Neurotoxins; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D055372:AMP-Activated Protein Kinases; D002118:Calcium