Monosodium glutamate induces memory and hepatic dysfunctions in mice: ameliorative role of Jobelyn® through the augmentation of cellular antioxidant defense machineries

Investigation of the effects of monosodium glutamate and tannic acid on the glutathione and thioredoxin systems in the liver of rats

While there is no conclusive evidence that monosodium glutamate (MSG, a food additive) directly causes liver cancer in humans, certain studies suggest a potential link between MSG-induced liver injury and cancer development. This study aimed to evaluate the protective effect of tannic acid (TA, a natural polyphenol) against MSG-induced hepatotoxicity through the glutathione and thioredoxin systems. Twenty-four rats were randomly divided into control and experimental groups and treated with TA, MSG, and MSG+TA once daily by oral gavage for 21 days. In addition to major oxidative stress indicators (total glutathione; GSH + GSSG and malondialdehyde; MDA), mRNA expression changes and biological activity responses of components of the glutathione and thioredoxin systems were examined in the liver tissues of all animals. The results showed that MSG alone negatively affected both stress indicators and antioxidant system components (glutathione peroxidase; GPx, glutathione reductase; GR, glutathione-S-transferase; GST, and thioredoxin reductase; TrxR) in terms of mRNA expression and biological activity. However, the combination of MSG and TA demonstrated robust antioxidative effects, surpassing the outcomes of MSG treatment. Our results provide new insights into pivotal molecular targets and protective candidates that should be focused on in future in vivo and in vitro HCC research.

Rutin and Moringa oleifera leaf extract prevent monosodium glutamate-induced testicular toxicity in adult male albino rats

Introduction

Monosodium glutamate (MG) is a substance often used to enhance food flavor, but its effect on the reproductive system is known to have a negative impact. This study assessed the protective effects of rutin (RUT) and Moringa oleifera leaf extract (MOLE) on testicular toxicity induced by MG in rats.

Methods

There were six groups: Control, RUT, MOLE, MG, RUT + MG, and MOLE + MG. The critical parameters measured were testicular index, hormone levels, antioxidants, oxidative stress markers, inflammation, apoptosis and histopathological changes.

Results

Following MG exposure (60 mg/kg/day for 30 days), the testicular index and serum testosterone, LH, and FSH levels were significantly reduced. The markers of oxidative stress increased, whereas the antioxidants decreased. The levels of inflammatory and apoptotic markers increased. The increased expression of inflammatory and apoptotic markers and significant testicular tissue damage, including degenerative changes in the seminiferous tubules, infiltration of inflammatory cells, and deposition of collagen fibers were investigated in addition to an increase in inflammatory and apoptotic markers.

Discussion

The present study showed that pre-administration of RUT or MOLE ameliorated the deleterious effects of MG, possibly due to antioxidant and anti-inflammatory properties, indicating a protective effect of RUT and MOLE on MG-induced testicular toxicity.

Mini review of plant products as food supplement against MSG-induced liver injury: antioxidant, oxidative stress and histological prospects

Monosodium glutamate (MSG) is an odorless white solid crystalline derived from the amino acid glutamic acid. It is widely used as a flavor enhancer, but its excessive consumption has been associated with toxicity to various organs. In MSG-induced liver injury, few mechanisms have been identified, which started with the generation of reactive oxygen species that leads to oxidative stress which further causes liver injury. In response to this health concern, there is growing interest in various plant products such as plant extracts, flavonoids and phenolic compounds that were able to minimize oxidative stress, serum transaminases and scavenge free radicals in the liver after MSG administration. This review explores the potential of various plant products as dietary supplements to MSG-induced liver injury, focusing on their antioxidant activities, modulatory effects on liver function markers, and histological outcomes. By compiling this evidence, this review provides insights into their potential as preventive strategies against MSG-related liver toxicity, supporting their inclusion in dietary regimens for the maintenance of liver function.

Protective effect of Danshensu against neurotoxicity induced by monosodium glutamate in adult mice and their offspring

Excessive neuronal excitation by glutamate is a well-established cause of neurotoxicity, leading to severe impairment of brain function. Excitotoxicity is a key factor in numerous neurodegenerative conditions. In this study, we investigated the neuroprotective effects of Danshensu (DSS) against monosodium glutamate (MSG)-induced neurotoxicity in adult mice and their offspring. We randomly divided one hundred 8-week-old Kunming mice (equal number of males and females) into a control group and an experimental group. The experimental group was further subdivided into various treatment groups, including MSG gavage treatment, bwbw DSS treatment group 1 (bwbw DSS treatment group 2, a drug control group, and a normal control group (receiving an equal volume of physiological saline for ten consecutive days). Additionally, another one hundred healthy 8-week-old Kunming mice were similarly divided into groups and treated. These mice were paired randomly (one male and one female) and pregnant females were housed separately to obtain offspring. Subsequently, we conducted histological and behavioral analyses on adult mice and their offspring. MSG treatment induced significant cellular edema and hippocampal damage in both the treated mice and their offspring. However, varying doses of DSS effectively counteracted the neurotoxic effects of MSG, with no adverse impact on brain tissue structure or neural function in either adult mice or their offspring. Behavioral experiments further confirmed that DSS exerted a substantial protective effect against MSG-induced impairment of learning and memory in the treated adult mice and their offspring, in addition to mitigating central nervous system overexcitation and inhibiting exploratory behavior. In conclusion, DSS exerts significant protective effects against MSG-induced neurotoxicity in both adult mice and their offspring.

Neuroprotective Potential of Tannic Acid Against Neurotoxic Outputs of Monosodium Glutamate in Rat Cerebral Cortex

Glutamate in monosodium glutamate (MSG), which is widely used in the food industry, has an important role in major brain functions such as memory, learning, synapse formation, and stabilization. However, extensive use of MSG has been linked with neurotoxicity. Therefore, in addition to clarifying the underlying mechanisms of MSG-induced neurotoxicity, it is also important to determine safe agents that can diminish the damage caused by MSG. Tannic acid (TA) is a naturally occurring plant polyphenol that exhibits versatile physiological effects such as anti-inflammatory, anti-carcinogenic, antioxidant, and radical scavenging. This study was conducted to assess the neurotoxic and neuroprotective effects of these two dietary components in the rat cerebral cortex. Twenty-four Sprague Dawley rats were divided into 4 equal groups and were treated with MSG (2 g/kg) and TA (50 mg/kg) alone and in combination for 3 weeks. Alterations in oxidative stress indicators (MDA and GSH) were measured in the cortex tissues. In addition, changes in enzymatic activities and gene expression patterns of antioxidant system components (GST, GPx, CAT, and SOD) were investigated. Furthermore, mRNA expressions of FoxO transcription factors (Foxo1 and Foxo3) and apoptotic markers (Casp3 and Casp9) were assessed. Results revealed that dietary TA intake significantly rehabilitated MSG-induced dysregulation in cortical tissue by regulating redox balance, cellular homeostasis, and apoptosis. The present study proposes that MSG-induced detrimental effects on cortical tissue are potentially mitigated by TA via modulation of oxidative stress, cell metabolism, and programmed cell death.

Potential Defence Mechanisms Triggered by Monosodium Glutamate Sub-Chronic Consumption in Two-Year-Old Wistar Rats

Monosodium glutamate (MSG) is the sodium salt of glutamic acid (GLA), used as a flavour enhancer. MSG is considered a controversial substance. It is incriminated in disturbing the antioxidant system, but also has beneficial effects, as GLA metabolism plays a crucial role in homeostasis. This study highlights which positive or negative aspects of MSG sub-chronic consumption are better reflected in subjects potentially affected by advanced age. Daily doses of MSG were administered to four groups of two-year-old Wistar rats for 90 days: (I) 185 mg/kg bw, (II) 1500 mg/kg bw, (III) 3000 mg/kg bw and (IV) 6000 mg/kg bw, compared to a MSG non-consumer group. Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, direct and total bilirubin, total cholesterol, triglycerides, creatinine and urea levels were analysed; stomach, liver and kidney samples were subjected to histopathological analysis. Although, in most cases, there were no statistical differences, interesting aspects of the dose-effect relationship were observed. After MSG sub-chronic consumption, the positive aspects of GLA seem to be reflected better than the negative ones. The hormesis effect, with low-level reactive oxygen species' protective effects and GLA metabolism, may represent the hypothesis of a potential defence mechanism triggered by MSG sub-chronic consumption in ageing rats.

Antioxidant and Anticholinesterase Properties of the Aqueous Extract of Balanites aegyptiaca L. Delile Fruit Pulp on Monosodium Glutamate-Induced Excitotoxicity in Swiss Mice

Balanites aegyptiaca L. Delile (B. aegyptiaca) is used in traditional medicine for the treatment of memory impairment. This work aims to evaluate the antioxidant and anticholinesterase potential of BA fruit pulp extract on excitotoxicity induced by monosodium glutamate (MSG). MSG was administered 30 minutes after treatment with B. aegyptiaca aqueous fruit pulp extract (50, 125, 250, and 500 mg/kg) and vitamin C (100 mg/kg) for 30 days. The negative control group received only MSG, while the control group was given distilled water daily. Behavioral tests parameters (using the novel object recognition, Y-maze, and Barnes maze tests), oxidative stress biomarkers (malondialdehyde, superoxide dismutase, and catalase), nitric oxide, and acetylcholinesterase activity and hippocampal architecture were evaluated. Results obtained revealed that different doses of B. aegyptiaca significantly reversed the deleterious effect of MSG on memory. This was displayed by a significant ( $p<0.05$ ) increment in the percentage of spontaneous alternation in the Y-maze test and a significant ( $p<0.001$ ) increase in discrimination index in novel object recognition observed with 500 mg/kg extract dose. Moreover, the extract (250 and 500 mg/kg doses) significantly ( $p<0.001$ ) increased direct search strategy and significantly decreased ( $p<0.01$ ) the time taken to find the target hole in the Barnes maze. A modulation of hyperactivity was observed after administration of all extract doses compared to the negative control group in the open arena. Furthermore, the highest dose of the extract caused a significant ( $p<0.001$ ) improvement in antioxidant enzymes activity, associated with a significant ( $p<0.001$ ) decrement in nitric oxide and malondialdehyde concentrations and a significant ( $p<0.01$ ) decrease in acetylcholinesterase activity. Treatment with the extract also restored normal hippocampal cell architecture. B. aegyptiaca fruit pulp extract could thus confer neuroprotection through its antioxidant and anticholinesterase potential.

Glutamate - A multifaceted molecule: Endogenous neurotransmitter, controversial food additive, design compound for anti-cancer drugs. A critical appraisal

One of the most widely used flavour enhancers in the food industry is monosodium glutamate (MSG). MSG consumption has been on an upward trend, worrying in terms of potential toxic effects. This review is focused on the long-term toxicity of MSG and the experimental evidence that supports it. The article's primary purpose was to survey recently published data regarding the consumption of MSG within safe limits. The administered doses in animal models are very varied and have given rise to controversy. Also, the paper comprises pathways to lower MSG toxicity and highlight other underexploited biological effects, as anti-cancer potential. The administration of MSG, combined with various compounds, has been shown benefit against toxic effects. Several recent studies have identified a possible mechanism that recommends MSG and some derivatives as potential anti-cancer agents. New anti-cancer compounds based on the glutamic acid structure must be studied and further exploited. International regulations require harmonization of safe doses of MSG based on current scientific studies. Replacing MSG with other umami flavour enhancers may be a safer alternative for human health in the future. The biological consequences of MSG consumption or therapeutical administration have not been fully deciphered yet.