Growth Differentiation Factor-11 Causes Neurotoxicity During Ischemia in vitro.

Brad A Sutherland,Zoi Alexopoulou,Gina Hadley,Ain A Neuhaus,Karl J Morten,Nareg Kalajian,Alastair M Buchan,Yvonne Couch,Tiffany A Lodge

doi:10.3389/fneur.2020.01023

Brad A Sutherland, Zoi Alexopoulou + Show 7 more

Open Access

https://doi.org/10.3389/fneur.2020.01023

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Abstract

Age-related neuronal dysfunction can be overcome by circulating factors present in young blood. Growth differentiation factor-11 (GDF-11), a systemic factor that declines with age, can reverse age-related dysfunction in brain, heart and skeletal muscle. Given that age increases susceptibility to stroke, we hypothesized that GDF-11 may be directly protective to neurons following ischemia. Primary cortical neurons were isolated from E18 Wistar rat embryos and cultured for 7–10 days. Neurons were deprived of oxygen and glucose (OGD) to simulate ischemia. Neuronal death was assessed by lactate dehydrogenase, propidium iodide or CellTox™ green cytotoxicity assays. 40 ng/mL GDF-11 administration during 2 h OGD significantly increased neuronal death following 24 h recovery. However, GDF-11 pre-treatment did not affect neuronal death during 2 h OGD. GDF-11 treatment during the 24 h recovery period after 2 h OGD also did not alter death. Real-time monitoring for 24 h revealed that by 2 h OGD, GDF-11 treatment had increased neuronal death which remained raised at 24 h. Co-treatment of 1 μM SB431542 (ALK4/5/7 receptor inhibitor) with GDF-11 prevented GDF-11 neurotoxicity after 2 h OGD and 24 h OGD. Transforming growth factor beta (TGFβ) did not increase neuronal death to the same extent as GDF-11 following OGD. GDF-11 neurotoxicity was also exhibited following neuronal exposure to hydrogen peroxide. These results reveal for the first time that GDF-11 is neurotoxic to primary neurons in the acute phase of simulated stroke through primarily ALK4 receptor signaling.

Highlights

The increased life expectancy of twenty-first century living has led to a substantial rise in the number of age-related disorders including stroke
At 24 h recovery following 2 h oxygen and glucose (OGD) (Figure 1C), the OGD group continued to have significantly increased cell death compared to normoxia [F(1, 48) = 111.1, p < 0.0001], with growth differentiation factor-11 (GDF-11) increasing cell death compared to OGD alone
Recent studies have pointed toward factors that are present in young blood such as GDF-11, that could have potential neuroprotective effects [4, 10, 11]

Summary

Introduction

The increased life expectancy of twenty-first century living has led to a substantial rise in the number of age-related disorders including stroke. Two recent studies have trialed GDF-11 as a neuroprotectant in middle cerebral artery occlusion models, and both showed that recombinant GDF-11 administration reduced neurobehavioural deficits through the augmentation of angiogenesis, endothelial cell proliferation and increased neural precursor proliferation out to 14 days post-stroke [10, 11]. Further evidence supporting this was the fact that SB431542, a ALK4/5/7 receptor inhibitor, blocked the protective effects of GDF-11 [10, 11]

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