Neuroprotective Effect of HIF Prolyl Hydroxylase Inhibition in an In Vitro Hypoxia Model.

Maria Savyuk,Dmitry Hushpulian,Mikhail Krivonosov,Mikhail Ivanchenko,Anna Khristichenko,Andrey Poloznikov,Guzal Abuzarova,Sergey Nikulin,Elena Mitroshina,Evgeny Tonevitsky,Irina Gazaryan,Maria Vedunova,Tatiana Mishchenko

doi:10.3390/antiox9080662

Abstract

A novel potent analog of the branched tail oxyquinoline group of hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitors, neuradapt, has been studied in two treatment regimes in an in vitro hypoxia model on murine primary hippocampal cultures. Neuradapt activates the expression of HIF1 and HIF2 target genes and shows no toxicity up to 20 μM, which is more than an order of magnitude higher than its biologically active concentration. Cell viability, functional activity, and network connectivity between the elements of neuronal networks have been studied using a pairwise correlation analysis of the intracellular calcium fluctuations in the individual cells. An immediate treatment with 1 μM and 15 μM neuradapt right at the onset of hypoxia not only protects from the death, but also maintains the spontaneous calcium activity in nervous cells at the level of the intact cultures. A similar neuroprotective effect in the post-treatment scenario is observed for 15 μM, but not for 1 μM neuradapt. Network connectivity is better preserved with immediate treatment using 1 μM neuradapt than with 15 μM, which is still beneficial. Post-treatment with neuradapt did not restore the network connectivity despite the observation that neuradapt significantly increased cell viability at 1 μM and functional activity at 15 μM. The preservation of cell viability and functional activity makes neuradapt promising for further studies in a post-treatment scenario, since it can be combined with other drugs and treatments restoring the network connectivity of functionally competent cells.

Highlights

Hypoxia is a widespread pathological process accompanying various diseases including ischemia, trauma, diabetes mellitus, Alzheimer’s disease, etc
The current study aims at testing a novel PHD inhibitor [13], an improved analog of adaptaquin [14], with respect to its neuroprotective properties in an in vitro hypoxia model, with emphasis on the functional neural network activity
Immediate treatment with a PHD inhibitor right after ischemia is neuroprotective despite the exact mechanism is controversial and possibly hypoxia-inducible factor (HIF)-independent [49]

Summary

Introduction

Hypoxia is a widespread pathological process accompanying various diseases including ischemia, trauma, diabetes mellitus, Alzheimer’s disease, etc. Even a short-term hypoxia can lead to functional and structural changes in tissues and organs. The most sensitive organ to oxygen deprivation is brain. Studies on protective mechanisms compensating for oxygen deficiency focus on the oxygen sensor system controlled by a family of hypoxia-inducible factors (HIFs) [2]. HIFs are heterodimers consisting of constitutively expressed β-subunit, insensitive to oxygen, and hypoxia-regulated α-subunit [3]. The stability of the latter is regulated by hydroxylation with oxygen via a reaction catalyzed by HIF prolyl hydroxylases (HIF PHD), a group of non-heme iron α−ketoglutarate (αKG)-dependent dioxygenases [4]

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Discussion

Conclusion