Abstract
INTRODUCTION
Glycine is a nonessential amino acid with known neuroprotective effects. Subarachnoid hemorrhage (SAH) is a form of stroke associated with high mortality and morbidity. Despite extensive research, the treatment for SAH is limited. The present study was designed to investigate the role of glycine in neuroprotection following SAH. We have previously demonstrated that glycine is involved in neuroprotection in intracerebral hemorrhage via the PTEN/AKT signal pathway. However, whether it has a role in inducing neuroprotection following SAH is not known.
METHODS
We established the SAH model, evaluated the SAH grade, neurological scores, brain water content, glycine-mediated C (FJC) staining, cell viability and LDH release, and did cortical neuron and microglia culture. Treatment was conducted by intracerebroventricular injection. Cultured cortical neurons and cultured cortical microglia were treated with standard ECS for 60 min and then treated with glycine (100 μM) for 60 min. Cell replacement medium was used for subsequent experiments. vPCR was performed on the Opticon 2 real-time polymerase chain reaction (PCR) detection system using the corresponding primers and SYBR gene PCR master mix.
RESULTS
In this present study, we show evidence of glycine mediated amelioration of neuronal death and brain edema following SAH via a novel pathway. Following SAH there is evidence of downregulation of S473 phosphorylation of AKT (p-AKT), which is reversed with glycine treatment. We also found that glycine-regulated neuroprotection following SAH via AKT activation. Glycine was shown to down-regulate PTEN by up-regulating miRNA-26b, followed by activation of AKT, resulting in inhibition of neuronal death. Inhibition of AKT, PTEN depletion or suppression of miRNA-26b blocked the neuroprotective effect of glycine. Glycine treatment also suppresses SAH-induced M1 microglial polarization and promotes anti-inflammation, which indirectly inhibits neuronal death.
CONCLUSION
Glycine has neuroprotective effects in SAH injury and is mediated by the miRNA-26b/PTEN/AKT signal pathway, which may be a therapeutic target for treatment of SAH injury.