Effect of monosodium glutamate on striato-hippocampal acetylcholinesterase level in the brain of male Wistar albino rats and its implications on learning and memory during aging

Abstract

Glutamate is one of the most abundant excitatory neurotransmitters of brain, plays an important role in learning and memory. Monosodium glutamate (MSG) is a sodium salt of L-glutamate, a well-known fl avor enhancer. Because of its capacity to increase the palatability, nowadays it is most widely used in all households and fast foods. The present study investigates the effect of MSG on striato-hippocampal acetylcholinesterase (AChE) level in the brain of male wistar albino rats and its implications on learning and memory during aging. The experimental groups consisted of 3-4 weeks old Wistar albino rats and were divided into group I and group II. These groups were again subdivided into control group treated with laboratory diet, 100 mg MSG, 400 mg MSG, 2 g MSG and 4 g MSG group treated with various doses of MSG/ kg body weight for sixty days. Immediately after 60 days of MSG treatment, the group I was used for the analysis of body weight, T-maze test, novel object recognition test (NOR) and AChE level while group II was kept free of MSG for further sixty days and later used for the above experiments. The results showed that group I animals neither have a dose dependent increase in body weight, a decline in the T-maze response, reduced discrimination index in NOR test and an increase in AChE level. However, the changes were signifi cant at 4 g MSG treated group. The group II animals did not showed any signifi cant differences when compared to control group. Thus the study revealed that a long term administration of MSG has a capacity to cause cognitive impairment but is not perpetual, during the life time, due to normal diet and natural healing mechanisms in the body ameliorates the toxic effects of MSG and showed gradual increase in the cognitive parameters, however it take a long time.

Effect of Monosodium Glutamate on the Cerebellar Cortex of Male Albino Rat and Protective Role of Vitamin C

“…The present study demonstrated that there was a significant increase of the rats' weight from the beginning to the end of the study which may be caused by the fact that MSG increases appetite, and this is in agreement with El-Helbawy et al (14) who documented that the effects of MSG evaluated after a period of 14 days' treatment in young rats showed a statistically highly significant increase (P<0.001) in the mean body weight of rats compared with controls. Another study also was in agreement with current one, demonstrating that low and high doses of MSG treatment increases body weight (15) . The present study clarified that, the molecular cell layer appeared as a zone lying superficial to Purkinje cell layer.…”

Effects of Monosodium Glutamate (MSG) on Neuron Damages in Hippocampus in Sprague-Dawley rats

“…G lutamate is essential component for neurotransmitter, but excessive glutamate levels would result the accumulation in synaptic cleftsthatwould be excitotoxic to nerve tissues.This accumulation would lead to overstimulation of glutamate receptors, in particular the N-methyl-D-aspartate (NMDA) receptors andactivate multiplepathways thatcause neuron damages and therefore affect the function of nerve tissues. 3,5,12,13 Our data suggested that the percentage of damaged neurons wasincreased in all MSG treatment groupsand wasin dose-dependent effect. The damaged nerve cells werecharacterized by chromatin condensation and pyknotic nucleus.…”

“…4 The abundance of glutamate in cerebral cortex and hippocampal dentate gyrus and striatum indicating that it has an important role in cognitive functions, including learning and memory. 2,3,[5][6][7][8] Therefore, the effects of MSG on neurons become a concerning issue. A study in early life period of animals shown that high concentration of MSG may act as neurotoxic or excitotoxic agent.…”

“…9 MSG also possibly damagesthe central nervous system cells resulting abnormal histologicalexaminations of the cerebral cortex and hippocampus, depletion of cerebral cortex layer, damage to neurons of primary sensory area of cerebral cortex, and damage to the paraventricular nucleus of neonates whose parents fed with MSG. 2,5,10,11 Since glutamate is an essential amino acid, more thorough and vigorous studies are necessary to validate the root cause of the vivid health consequences in particular in neuropathology.The aim of this study was toassess the effects of MSG on neuron damages in the hippocampus areas in animal model.…”

Effects of in utero exposure to monosodium glutamate on locomotion, anxiety, depression, memory and KCC2 expression in offspring

“…Although Overa‐Cortes (Olvera‐Cortes et al, 2005) and López‐Vázquez (López‐Vázquez et al, 2019) have reported behaviour deficits in the Morris water maze performances of mice neonatally exposed to MSG, this was not observed in our study. It has been reported that, MSG‐induced decrease in cognitive functioning is reversed by normal diet and natural healing mechanisms that ameliorates the toxic effect as the animal ages (Sreejesh & Sreekumaran, 2018). This causes a gradual increase in cognitive parameters and perhaps explains the lack of any effect in the Morris water maze in our study.…”