Assessment of the neurotoxicity of monosodium glutamate on neural stem cells and hippocampal neurogenesis in a rodent model.

Monosodium glutamate (MSG) is a widely used flavor enhancer in processed foods and valued for its ability to enhance the savory taste known as umami. MSG is classified as non-toxic and recognized as a safe food additive with no specific usage restrictions in many countries. However, neurotoxic studies on MSG have primarily focused on neurons, and the effects of MSG on neural stem cells (NSCs) have not been reported. This study aimed to evaluate the neurotoxic effect of MSG on NSCs and hippocampal neurogenesis in a rodent model. In vitro studies showed that MSG induces cytotoxicity in primary neuron cultures but has no toxic effect on NSCs. Furthermore, in vivo studies on 4-week-old male C57BL/6 mice orally administered MSG and sodium chloride (NaCl) for two weeks revealed that neither MSG nor NaCl induced changes in the expressions of neuronal markers or glutamate receptors in the hippocampus. In addition, no differences in NSC proliferation or survival were detected, and MSG did not adversely affect the neuronal differentiation of NSCs. Moreover, neurobehavioral tests showed that MSG treatment did not impair spatial learning and memory. These findings provide a first assessment of the neurotoxic effects of MSG on NSCs and hippocampal neurogenesis.