Thiopental Inhibits Global Protein Synthesis by Repression of Eukaryotic Elongation Factor 2 and Protects from Hypoxic Neuronal Cell Death

Abstract

Ischemic and traumatic brain injury is associated with increased risk for death and disability. The inhibition of penumbral tissue damage has been recognized as a target for therapeutic intervention, because cellular injury evolves progressively upon ATP-depletion and loss of ion homeostasis. In patients, thiopental is used to treat refractory intracranial hypertension by reducing intracranial pressure and cerebral metabolic demands; however, therapeutic benefits of thiopental-treatment are controversially discussed. In the present study we identified fundamental neuroprotective molecular mechanisms mediated by thiopental. Here we show that thiopental inhibits global protein synthesis, which preserves the intracellular energy metabolite content in oxygen-deprived human neuronal SK-N-SH cells or primary mouse cortical neurons and thus ameliorates hypoxic cell damage. Sensitivity to hypoxic damage was restored by pharmacologic repression of eukaryotic elongation factor 2 kinase. Translational inhibition was mediated by calcium influx, activation of the AMP-activated protein kinase, and inhibitory phosphorylation of eukaryotic elongation factor 2. Our results explain the reduction of cerebral metabolic demands during thiopental treatment. Cycloheximide also protected neurons from hypoxic cell death, indicating that translational inhibitors may generally reduce secondary brain injury. In conclusion our study demonstrates that therapeutic inhibition of global protein synthesis protects neurons from hypoxic damage by preserving energy balance in oxygen-deprived cells. Molecular evidence for thiopental-mediated neuroprotection favours a positive clinical evaluation of barbiturate treatment. The chemical structure of thiopental could represent a pharmacologically relevant scaffold for the development of new organ-protective compounds to ameliorate tissue damage when oxygen availability is limited.

Gravireceptors in eukaryotes—a comparison of case studies on the cellular level

“…The activated calmodulin was found to stimulate an adenylyl cyclase as indicated by inhibitor studies with indomethacine as well as several calmodulin blockers 37 all of which block gravitaxis in Euglena . In contrast, forskulin activates the adenylyl cyclase 38 and augments gravitaxis. All these results indicate that the activated calmodulin induces the adenylyl cyclase to produce cyclic adenosine monophosphate (cAMP).…”

Thiopental protects human neuroblastoma cells from apoptotic cell death — Potential role of heat shock protein 70

“…This practice is based on numerous reports about the neuroprotective properties of thiopental in the context of neuronal hypoxia/ischemia [20][21][22][23].…”

Gravitaxis in Euglena

“…Trifluoperazine and fluphenazin as well as W7 are specific calmodulin inhibitors (Naccache 1985;Russo et al 2014;Son et al 2014) and were found to inhibit gravitaxis in E. gracilis . Likewise, indomethacine impairs the adenylyl cyclase (Wang et al 2012) and decreases the precision of gravitactic orientation in E. gracilis Häder et al 2006), while forskolin activates the adenylyl cyclase (Schwer et al 2013) and augments gravitaxis in Euglena . Phosphodiesterase quenches the cAMP signal (Cai et al 2015).…”