Histopathological and biochemical evaluation of the effects of monosodium glutamate on cognitive memory and brain functions in rats

Abstract Monosodium glutamate (MSG) is a widely used flavoring agent worldwide. Although MSG is found in many packaged and ready-to-eat foods, it also has many side effects. The aim of this study was to investigate the effects of MSG on body weight, brain and cognitive functions histopathologically and biochemically. Starting from the first day of the experiment, 4 mg/kg saline was given to the control group and 4 mg/kg MSG to the experimental group for 28 days. The rats were also subjected to Barnes maze test every day. At the end of the experiment, the animals were decapitated, and brain tissues were removed. Biochemical and histopathological analyses were performed on the removed brain tissues. At the end of the experiment, there was a statistically significant ( p < 0.000) increase in the average weight of the experimental group. There was a statistically significant difference between the experimental group and the control group in terms of Barnes Maze test times ( p < 0.000) and number of trials ( p < 0.001). Total antioxidant status (TAS) was 1.75 ± 0.14 mmol Trolox equiv/L in the control group and 1.40 ± 0.21 mmol Trolox Equiv/L in the experimental group. Total oxidant status (TOS) was 4.22 ± 1.71 µmol H2O2 Equiv/L in the control group and 7.15 ± 1.35 µmol H2O2 Equiv/L in the experimental group. Oxidative stress index (OSI) was 2.46 ± 1.05 in the control group and 5.23 ± 1.40 in the experimental group. These differences in TAS, TOS and OSI were statistically significant ( p < 0.000). Histological analysis showed shrinkage, degeneration, pyknosis, karyolysis, necrosis and mild satellitosis in the experimental group. The results of this study revealed that MSG had negative effects on body weight, brain function and cognitive capacity of rats, caused negative changes in the cellular structure of brain tissue and increased oxidative stress in the tissue.