Selective overexpression of excitatory amino acid transporter 2 (EAAT2) in astrocytes enhances neuroprotection from moderate but not severe hypoxia–ischemia

Abstract

Attempts have been made to elevate excitatory amino acid transporter 2 (EAAT2) expression in an effort to compensate for loss of function and expression associated with disease or pathology. Increased EAAT2 expression has been noted following treatment with β-lactam antibiotics, and during ischemic preconditioning (IPC). However, both of these conditions induce multiple changes in addition to alterations in EAAT2 expression that could potentially contribute to neuroprotection. Therefore, the aim of this study was to selectively overexpress EAAT2 in astrocytes and characterize the cell type specific contribution of this transporter to neuroprotection. To accomplish this we used a recombinant adeno-associated virus vector, AAV1–glial fibrillary acidic protein (GFAP)–EAAT2, designed to selectively drive the overexpression of EAAT2 within astrocytes. Both viral-mediated gene delivery and β-lactam antibiotic (penicillin-G) treatment of rat hippocampal slice cultures resulted in a significant increase in both the expression of EAAT2, and dihydrokainate (DHK) sensitive glutamate uptake. Penicillin-G provided significant neuroprotection in rat hippocampal slice cultures under conditions of both moderate and severe oxygen glucose deprivation (OGD). In contrast, viral-mediated overexpression of EAAT2 in astrocytes provided enhanced neuroprotection only following a moderate OGD insult. These results indicate that functional EAAT2 can be selectively overexpressed in astrocytes, leading to enhanced neuroprotection. However, this cell type specific increase in EAAT2 expression offers only limited protection compared to treatment with penicillin-G.