Orexin-A promotes Glu uptake by OX1R/PKCα/ERK1/2/GLT-1 pathway in astrocytes and protects co-cultured astrocytes and neurons against apoptosis in anoxia/hypoglycemic injury in vitro

Abstract

Orexin-A, which is an endogenous neuropeptide, is reported to have a protective role in ischemic stroke. High-concentration glutamic acid (Glu) induced by hypoxia injury in ischemic stroke can be inhibited by glial glutamate transporter GLT-1 which is only expressed in astroglia cells. A previous study reported that Orexin-A may regulate GLT-1 expression. However, the role of orexin-A in the regulation of GLT-1 in ischemic stroke still remains unclear. In this study, we aimed to investigate the effect and the underlying mechanism of orexin-A on Glu uptake in astrocytes in vitro and this effect on protecting the neurons from anoxia/hypoglycemic injury. The expression of GLT-1 significantly increased in the astrocytes with orexin-A treatment under anoxia/hypoglycemic conditions, promoting the uptake of Glu and inhibiting the apoptosis of co-cultured cells of astrocytes and neurons. However, these effects were significantly weakened by treatment with orexin-A receptor 1 (OX1R) antagonist. Orexin-A significantly up-regulated the expressions of PKCα and ERK1/2 under anoxia/hypoglycemic conditions in astrocytes, whereas the OX1R antagonist markedly reversed the effect. Furthermore, PKCα or ERK1/2 inhibitor significantly constrained the GLT-1 expression in astrocytes and facilitated the apoptosis of co-cultured cells, and GLT-1 overexpression could reverse those effects of PKCα or ERK1/2 inhibitor. Taken together, orexin-A promoted the GLT-1 expression via OX1R/PKCα/ERK1/2 pathway in astrocytes and protected co-cultured cells against anoxia/hypoglycemic injury.

Orexin-A protects SH-SY5Y cells against H2O2-induced oxidative damage via the PI3K/MEK1/2/ERK1/2 signaling pathway

“…These results are consistent with those of other studies. 27 – 29 Our data indicate that the neuroprotective effects of Orexin-A involve suppression of MEK 1/2 /ERK 1/2 activity.…”

RNA-seq expression profiling of rat MCAO model following reperfusion Orexin-A

“…Orexin-A increases glucose transporter 4 expression and lipid accumulation in 3T3-L1 adipocytes via ERK1/2, JNK and p38 MAPK signalling [ 25 , 26 ]. Orexin-A treatment promoted the uptake of Glu via the OX1R/PKCα/ERK1/2 pathway and protected co-cultured cells against anoxia/hypoglycaemic injury in astrocytes [ 27 ]. Orexin-A stimulates ERK 1/2 phosphorylation and facilitates cell migration via the PLC-PKCα signalling pathway in cultured rat astrocytes [ 28 ].…”

LncRNA BIRF Promotes Brain Ischemic Tolerance Induced By Cerebral Ischemic Preconditioning Through Upregulating GLT-1 via Sponging miR-330-5p

“…For example, Emodin promoted Bcl-2 and GLT-1 expression to inhibit neuronal apoptosis and ROS generation via ERK-1/2 signaling pathway [ 46 ]. Orexin-A promotes glutamate uptake via the OX1R/PKCα/ERK1/2/GLT-1 pathway in astrocytes and protects co-cultured neurons and astrocytes against apoptosis in anoxia/hypoglycemic injury in vitro [ 47 ]. In the present study, BIRF or miR-330-5p regulates GLT-1 expression and neuron apoptosis.…”