A systematic review of the neuropathology and memory decline induced by monosodium glutamate in the Alzheimer's disease-like animal model

The Effect of Naringin on Cognitive-Behavioral Functions, CREB/BDNF Signaling, Cholinergic Activity, and Neuronal Density in the Hippocampus of an MSG-Induced Obesity Rat Model

The global rise in obesity and overweight over the past few decades has led to numerous associated disorders, including cognitive deficits. This study evaluate investigates the effects of Naringin (Nar) on memory and learning, anxiety-like behaviors, brain-derived neurotrophic factor (BDNF), cAMP responsive element binding protein (CREB), acetylcholinesterase (AChE) activity, and neuronal density in the CA₁/CA₃ subfields of the hippocampus in an MSG-induced obese obesity rat model. Forty-eight male Wistar rat pups were randomly divided into four groups: Control, MSG, MSG + Nar50, and MSG + Nar100. MSG (4 g/kg BW) was administered subcutaneously in the cervical region from PND 2 to PND10, while Nar (50 mg/kg BW and 100 mg/kg BW) was administered orally from PND30 to PND42. After the treatment period, cognitive (working memory and passive avoidance) and anxiety-related tests (elevated plus maze and novelty-suppressed feeding test) were performed. Subsequently, hippocampal protein level of BDNF and CREB/BDNF gene expression, AChE activity and neuronal density in the CA₁ and CA₃ regions of the hippocampus were measured. Relative to the MSG group, the Nar-treated rats demonstrated improvements in spatial working memory, reduced anxiety-related behaviors, elevated hippocampal CREB and BDNF genes and BDNF protein levels, and reduced AChE activity. Additionally, Nar treatment increased neuronal density in the CA₁/CA₃ subfields of the hippocampus. These findings suggest that Nar enhances cognitive function and mitigates anxiety in MSG-induced obese rats by modulating CREB/BDNF signaling pathway, inhibiting AChE, and exerting neuroprotective effects in the hippocampus.

The protective efficacy of omega-3 polyunsaturated fatty acids on oxidative stress, inflammation, neurotransmitter perturbations, and apoptosis induced by monosodium glutamate in the brain of male rats

Exaggerated neuronal excitation by glutamate is a well-known cause of excitotoxicity, a key factor in numerous neurodegenerative disorders. This study examined the neurotoxic effect of monosodium glutamate (MSG) in the brain cortex of rats and focused on assessing the potential neuroprotective effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs). Four groups of adult male rats (n = 10) were assigned as follows; normal control, ω-3 PUFAs (400 mg/kg) alone, MSG (4 mg/g) alone, and MSG plus ω-3 PUFAs (4 mg/g MSG plus 400 mg/kg ω-3 PUFAs). Biochemical analysis, immunohistochemical, and histological examinations were conducted upon completion of the treatment protocol. Results revealed that MSG significantly increased malondialdehyde, nitric oxide, tumor necrosis factor-α, interleukin 1β, acetylcholinesterase, monoamine oxidase, and caspase-3. However, the MSG-treated group showed a decline in reduced glutathione, catalase, superoxide dismutase, dopamine, and serotonin. In addition, MSG caused histopathological changes in the cortical region which support the biochemical and immunohistochemical analysis. Supplementation of ω-3 PUFAs greatly improved the biochemical, immunohistochemical, and histopathological alterations induced by MSG administration in the brain cortex. Together, these findings revealed a neuroprotective effect of ω-3 PUFAs against MSG-induced toxicity in the brain cortex by attenuating oxidative damage, inflammation, neurochemical perturbations, and apoptosis.

Thyroid Hormone Neuroprotection Against Perfluorooctane Sulfonic Acid Cholinergic and Glutamatergic Disruption and Neurodegeneration Induction

Background: Perfluorooctane sulfonic acid (PFOS), a widely used industrial chemical, was reported to induce memory and learning process dysfunction. Some studies tried to reveal the mechanisms that mediate these effects, but how they are produced is still unknown. Basal forebrain cholinergic neurons (BFCN) maintain cognitive function and their selective neurodegeneration induces cognitive decline, as observed in Alzheimer's disease. PFOS was reported to disrupt cholinergic and glutamatergic transmissions and thyroid hormone action, which regulate cognitive processes and maintain BFCN viability. Objective/Methods: To evaluate PFOS neurodegenerative effects on BFCN and the mechanisms that mediate them, SN56 cells (a neuroblastoma cholinergic cell line from the basal forebrain) were treated with PFOS (0.1 µM to 40 µM) with or without thyroxine (T3; 15 nM), MK-801 (20 µM) or acetylcholine (ACh; 10 µM). Results: In the present study, we found that PFOS treatment (1 or 14 days) decreased thyroid receptor α (TRα) activity by decreasing its protein levels and increased T3 metabolism through increased deiodinase 3 (D3) levels. Further, we observed that PFOS treatment disrupted cholinergic transmission by decreasing ACh content through decreased choline acetyltransferase (ChAT) activity and protein levels and through decreasing muscarinic receptor 1 (M1R) binding and protein levels. PFOS also disrupted glutamatergic transmission by decreasing glutamate content through increased glutaminase activity and protein levels and through decreasing N-methyl-D-aspartate receptor subunit 1 (NMDAR1); effects mediated through M1R disruption. All these effects were mediated through decreased T3 activity and T3 supplementation partially restored to the normal state. Conclusions: These findings may assist in understanding how PFOS induces neurodegeneration, and the mechanisms involved, especially in BFCN, to explain the process that could lead to cognitive dysfunction and provide new therapeutic tools to treat and prevent its neurotoxic effects.

Treatment of manganese and lead poisoning with sodium para-aminosalicylic acid: A contemporary update

Sodium para-aminosalicylic acid (PAS-Na) treatment for manganese (Mn) intoxication has shown efficacy in experimental and clinical studies, giving rise to additional studies on its efficacy for lead (Pb) neurotoxicity and its associated mechanisms of neuroprotection. The difference between PAS-Na and other metal complexing agents, such as edetate calcium sodium (CaNa2-EDTA), is firstly that PAS-Na can readily pass through the blood-brain barrier (BBB), and complex and facilitate the excretion of manganese and lead. Secondly, PAS-Na has anti-inflammatory effects. Recent studies have broadened the understanding on the mechanisms associated with efficacy of PAS-Na. The latter has been shown to modulate multifarious manganese- and lead- induced neurotoxicity, via its anti-apoptotic and anti-inflammatory effects, as well as its ability to inhibit pyroptosis, and regulate abnormal autophagic processes. These observations provide novel scientific bases and new concepts for the treatment of lead, mercury, copper, thallium, as well as other toxic encephalopathies, and implicate PAS-Na as a compound with greater prospects for clinical medical application.

Investigating the effect of exposure to monosodium glutamate during pregnancy on development of autism in male rat offspring

In present study, we investigated the relationship between the pregnancy exposure to monosodium glutamate (MSG) and autism development in male offspring of rats. Pregnant Wistar rats were allocated into five groups. The first group was control group that pregnant animals received normal saline orally from day 1-18 of pregnancy. Group 2, 3 and 4 pregnant rats received different doses (1.5, 5 and 10 g/kg) of MSG by the same way respectively. Group 5 received 500 mg/kg of Valproic acid (VPA) on the 12.5th day of pregnancy. Different behavioral tests including marble burying, self-grooming, and Barnes maze test were performed on offspring. The levels of glutamate and GSH markers were also measured. The results showed that MSG similar to VPA led to induction of autistic anxiety and repetitive behaviors. It could also deteriorate the spatial memory. Besides we found that behavioral symptoms potentiated with increasing the MSG dosage. Similarly, we had an increase in glutamate and a reduction in GSH levels in offspring. Findings indicated that MSG was able to induce autism in offspring of rats in a dose-dependent way. This effect could be through increasing of glutamate and reduction of GSH. Consequently, MSG should be avoided during pregnancy.

Elossaily G, Vellapandian C, Prajapati B. Investigating the Potential Impact of Air Pollution on Alzheimer's Disease and the Utility of Multidimensional Imaging for Early Detection

Pollution is ubiquitous, and much of it is anthropogenic in nature, which is a severe risk factor not only for respiratory infections or asthma sufferers but also for Alzheimer's disease, which has received a lot of attention recently. This Review aims to investigate the primary environmental risk factors and their profound impact on Alzheimer's disease. It underscores the pivotal role of multidimensional imaging in early disease identification and prevention. Conducting a comprehensive review, we delved into a plethora of literature sources available through esteemed databases, including Science Direct, Google Scholar, Scopus, Cochrane, and PubMed. Our search strategy incorporated keywords such as "Alzheimer Disease", "Alzheimer's", "Dementia", "Oxidative Stress", and "Phytotherapy" in conjunction with "Criteria Pollutants", "Imaging", "Pathology", and "Particulate Matter". Alzheimer's disease is not only a result of complex biological factors but is exacerbated by the infiltration of airborne particles and gases that surreptitiously breach the nasal defenses to traverse the brain, akin to a Trojan horse. Various imaging modalities and noninvasive techniques have been harnessed to identify disease progression in its incipient stages. However, each imaging approach possesses inherent limitations, prompting exploration of a unified technique under a single umbrella. Multidimensional imaging stands as the linchpin for detecting and forestalling the relentless march of Alzheimer's disease. Given the intricate etiology of the condition, identifying a prospective candidate for Alzheimer's disease may take decades, rendering the development of a multimodal imaging technique an imperative. This research underscores the pressing need to recognize the chronic ramifications of invisible particulate matter and to advance our understanding of the insidious environmental factors that contribute to Alzheimer's disease.

Alzheimer's disease: the role of extrinsic factors in its development, an investigation of the environmental enigma

In the realm of Alzheimer's disease, the most prevalent form of dementia, the impact of environmental factors has ignited intense curiosity due to its substantial burden on global health. Recent investigations have unveiled these environmental factors as key contributors, shedding new light on their profound influence. Notably, emerging evidence highlights the detrimental role of various environmental contaminants in the incidence and progression of Alzheimer's disease. These contaminants encompass a broad spectrum, including air pollutants laden with ozone, neurotoxic metals like lead, aluminum, manganese, and cadmium, pesticides with their insidious effects, and the ubiquitous presence of plastics and microplastics. By meticulously delving into the intricate web connecting environmental pollutants and this devastating neurological disorder, this comprehensive chapter takes a deep dive into their involvement as significant risk factors for Alzheimer's disease. Furthermore, it explores the underlying molecular mechanisms through which these contaminants exert their influence, aiming to unravel the complex interactions that drive the pathogenesis of the disease. Additionally, this chapter proposes potential strategies to mitigate the detrimental effects of these environmental contaminants on brain health, with the ultimate goal of restoring and preserving typical cognitive function. Through this comprehensive exploration, we aim to enhance our understanding of the multifaceted relationship between neurotoxins and Alzheimer's disease, providing a solid foundation for developing innovative in-vivo models and advancing our knowledge of the intricate pathological processes underlying this debilitating condition.