Lanigan, SineadSineadLaniganO'Connor, J. J.J. J.O'Connor2019-03-202019-03-202017 Elsev2018-01-15Neurosciencehttp://hdl.handle.net/10197/9635During hypoxia a number of physiological changes occur within neurons including the stabilization of hypoxia-inducible factors (HIFs). The activity of these proteins is regulated by O2, Fe2+, 2-OG and ascorbate-dependant hydroxylases which contain prolyl-4-hydroxylase domains (PHDs). PHD inhibitors have been widely used and have been shown to have a preconditioning and protective effect against a later and more severe hypoxic insult. In this study we have investigated the neuroprotective effects of the PHD inhibitor, protocatechuic acid ethyl ester (ethyl 3,4, dihydroxybenzoate: EDHB) as well as its effects on synaptic transmission and plasticity in the rat hippocampus using electrophysiological techniques. We report for the first time, an acute concentration-dependent and reversible inhibitory effect of EDHB (10–100 μM) on synaptic transmission in the dentate gyrus but not Cornu Ammonis 1 (CA1) region which does not affect cell viability. This effect was attenuated through the application of the NMDA or GABAA receptor antagonists, AP-5 and picrotoxin in the dentate gyrus. There were no changes in the ratio of paired responses after EDHB application suggesting a post-synaptic mechanism of action. EDHB (100 μM), was found to inhibit synaptic plasticity in both the dentate gyrus and CA1 regions. Application of exogenous Fe2+ (100 μM) or digoxin (100 nM) did not reverse EDHB’s inhibitory effect on synaptic transmission or plasticity in both regions, suggesting that its effects may be HIF-independent. These results highlight a novel modulatory role for the PHD inhibitor EDHB in hippocampal synaptic transmission and plasticity. A novel post-synaptic mechanism of action may be involved possibly involving NMDA and GABAA receptor activation.enThis is the author’s version of a work that was accepted for publication in Neuroscience. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Neuroscience (369, (2018)) doi:10.1016/j.neuroscience.2017.11.011Protocatechuic acid ethyl ester/ethyl 3,4, dihydroxybenzoateProlyl hydroxylaseEPSPHypoxiaLTPHippocampusJournal Article36916818210.1016/j.neuroscience.2017.11.0112017-11-17https://creativecommons.org/licenses/by-nc-nd/3.0/ie/