Evidence of alterations in brain structure and antioxidant status following ‘low-dose’ monosodium glutamate ingestion

ObjectiveThe study investigated the effects of low dose monosodium glutamate (MSG) on the brain, with a view to providing information on its effects on neuronal morphology and antioxidant status in mice.MethodologySixty male mice (20–22 g) were divided into six groups of ten animals each. Vehicle (distilled water), a standard (l-glutamate at 10 mg/kg body weight) or MSG (10, 20, 40 and 80 mg/kg body weight) were administered orally for 28 days. Sections of the cerebrum, hippocampus and cerebellum were processed and stained using hematoxylin and eosin, examined under a microscope and captured images analysed. Plasma and brain levels of glutamate, glutamine, and antioxidants were assayed. Data obtained were analysed using descriptive and inferential statistics.ResultsMSG ingestion did not significantly alter body weight. Relative brain weight increased at 40 and 80 mg/kg compared to vehicle. Histological and histomorphometric changes consistent with neuronal damage were seen in the cerebrum, hippocampus and cerebellum at 40 and 80 mg/kg. Plasma glutamate and glutamine assay showed significant increase at 40 and 80 mg/kg while no significant difference in total brain glutamate or glutamine levels were seen. Levels of brain superoxide dismutase and catalase decreased with increasing doses of MSG, while nitric oxide (NO) increased at these doses.ConclusionThe study showed morphological alterations consistent with neuronal injury, biochemical changes of oxidative stress and a rise in plasma glutamate and glutamine. These data therefore still support the need for cautious consideration in the indiscriminate use of MSG as a dietary flavor enhancer.