Sulbactam protects neurons against double neurotoxicity of amyloid beta and glutamate load by upregulating glial glutamate transporter 1

Abstract

Amyloid beta (Abeta) synergistically enhances excitotoxicity of glutamate load by impairing glutamate transporter 1 (GLT1) expression and function, which exacerbates the development of Alzheimer’s disease (AD). Our previous studies have suggested that sulbactam can upregulate the expression levels and capacity of GLT1. Therefore, this study aims to investigate whether sulbactam improves neuronal tolerance against neurotoxicity of Abeta and glutamate load by up-regulating GLT1 in primary neuron-astrocyte co-cultures. Early postnatal P0-P1 Wistar rat pups’ cortices were collected for primary neuron-astrocyte cultures. Hoechst-Propidium Iodide (HO-PI) stain and lactate dehydrogenase (LDH) assays were used to analyze neuronal death. Cell counting kit 8 (CCK8) was applied to determine cell viability. Immunofluorescent staining and western blotting were used to assess protein expressions including GLT1, BAX, BCL2, cleaved caspase 3. Under double effect of Abeta and glutamate load, neurons lost more than that induced by Abeta or glutamate alone, shown as decreased cell viability, increased LDH concentration in the cultural medium, HO-PI positive stains and high cleaved caspase 3 expression and BAX/BCL2 ratio resulting from increased BAX and decreased BCL2 expression. Notably, pre-incubation with sulbactam significantly attenuated the neuronal loss and activation of apoptosis induced by both Abeta and glutamate in a dose-dependent manner. Simultaneously, both astrocytic and neuronal GLT1 expression was upregulated after sulbactam incubation. Taken together, it could be concluded that sulbactam protected neurons against double neurotoxicity of Abeta and glutamate load by upregulating GLT1 expression. The conclusion provides evidence for potential intervention using sulbactam in AD research.