Involvement of mGlu5 receptor in 3-nitropropionic acid-induced oxidative stress in rat striatum

Ozone pollution, oxidative stress, synaptic plasticity, and neurodegeneration

INTRODUCTION

Overpopulation and industrial growth result in an increase in air pollution, mainly due to suspended particulate matter and the formation of ozone. Repeated exposure to low doses of ozone, such as on a day with high air pollution levels, results in a state of chronic oxidative stress, causing the loss of dendritic spines, alterations in cerebral plasticity and in learning and memory mechanisms, and neuronal death and a loss of brain repair capacity. This has a direct impact on human health, increasing the incidence of chronic and degenerative diseases.

DEVELOPMENT

We performed a search of the PubMed, Scopus, and Google Scholar databases for original articles and reviews published between 2000 and 2018 and addressing the main consequences of ozone exposure on synaptic plasticity, information processing in cognitive processes, and the alterations that may lead to the development of neurodegenerative diseases.

CONCLUSIONS

This review describes one of the pathophysiological mechanisms of the effect of repeated exposure to low doses of ozone, which causes loss of synaptic plasticity by producing a state of chronic oxidative stress. This brain function is key to both information processing and the generation of structural changes in neuronal populations. We also address the effect of chronic ozone exposure on brain tissue and the close relationship between ozone pollution and the appearance and progression of neurodegenerative diseases.

Ozone pollution, oxidative stress, synaptic plasticity, and neurodegeneration

INTRODUCTION

Overpopulation and industrial growth result in an increase in air pollution, mainly due to suspended particulate matter and the formation of ozone. Repeated exposure to low doses of ozone, such as on a day with high air pollution levels, results in a state of chronic oxidative stress, causing the loss of dendritic spines, alterations in cerebral plasticity and in learning and memory mechanisms, and neuronal death and a loss of brain repair capacity. This has a direct impact on human health, increasing the incidence of chronic and degenerative diseases.

DEVELOPMENT

We performed a search of the PubMed, Scopus, and Google Scholar databases for original articles and reviews published between 2000 and 2018 and addressing the main consequences of ozone exposure on synaptic plasticity, information processing in cognitive processes, and the alterations that may lead to the development of neurodegenerative diseases.

CONCLUSIONS

This review describes one of the pathophysiological mechanisms of the effect of repeated exposure to low doses of ozone, which causes loss of synaptic plasticity by producing a state of chronic oxidative stress. This brain function is key to both information processing and the generation of structural changes in neuronal populations. We also address the effect of chronic ozone exposure on brain tissue and the close relationship between ozone pollution and the appearance and progression of neurodegenerative diseases.

Oxytocin Prevents the Development of 3-NP-Induced Anxiety and Depression in Male and Female Rats: Possible Interaction of OXTR and mGluR2

Huntington disease (HD) is a progressive neurological disorder with dominant motor symptoms. It also has psychiatric manifestations, like anxiety and depression, that can emerge themselves before motor symptoms and impose a major burden on patients. Oxytocin (OXT) is a newly emerged treatment for disorders like autism and schizophrenia and recently is using to alleviate depression and anxiety. In the current study, we investigated the behavioral and molecular effects of OXT on the development of anxiety and depression in 3-nitropropionic acid (3-NP)-induced model of HD. Anxiety- and depression-like behaviors as well as the levels of oxytocin receptor (OXTR), metabotropic glutamate receptor (mGluR) 2, mGluR5, and glutathione (GSH) were measured in striatum, hippocampus, prefrontal cortex, and amygdala. Also, we questioned if sex had any modulatory effect. We found that 3-NP increased anxiety and depression compared to controls. It also reduced the levels of OXTR and mGluR2, increased mGluR5, and reduced GSH in studied brain regions. Pretreatment with OXT before the injection of 3-NP ameliorated anxiety and depression. Additionally, it protected the brain from developing low levels of OXTR, mGluR2, and GSH and high levels of mGluR5 in studied regions. The protective effects of OXT were similar between male and female animals. These data suggest that OXTR, mGluR2, mGluR5, and GSH may contribute to psychiatric manifestations of HD. In addition, pretreatment with OXT could prevent the mood changes in male and female rats.

Neurotoxic Agent-Induced Injury in Neurodegenerative Disease Model: Focus on Involvement of Glutamate Receptors

Glutamate receptors play a crucial role in the central nervous system and are implicated in different brain disorders. They play a significant role in the pathogenesis of neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Although many studies on NDDs have been conducted, their exact pathophysiological characteristics are still not fully understood. In in vivo and in vitro models of neurotoxic-induced NDDs, neurotoxic agents are used to induce several neuronal injuries for the purpose of correlating them with the pathological characteristics of NDDs. Moreover, therapeutic drugs might be discovered based on the studies employing these models. In NDD models, different neurotoxic agents, namely, kainic acid, domoic acid, glutamate, β-N-Methylamino-L-alanine, amyloid beta, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1-methyl-4-phenylpyridinium, rotenone, 3-Nitropropionic acid and methamphetamine can potently impair both ionotropic and metabotropic glutamate receptors, leading to the progression of toxicity. Many other neurotoxic agents mainly affect the functions of ionotropic glutamate receptors. We discuss particular neurotoxic agents that can act upon glutamate receptors so as to effectively mimic NDDs. The correlation of neurotoxic agent-induced disease characteristics with glutamate receptors would aid the discovery and development of therapeutic drugs for NDDs.

Ebselen protects against behavioral and biochemical toxicities induced by 3-nitropropionic acid in rats: correlations between motor coordination, reactive species levels, and succinate dehydrogenase activity

The protective effect of ebselen was investigated against 3-nitropropionic acid (3-NP)-induced behavioral and biochemical toxicities in rats. Ebselen (10 or 25 mg/kg, intragastrically) was administered to rats 30 min before 3-NP (20 mg/kg, intraperitoneally) once a day for a period of 4 days. Locomotor activity, motor coordination, and body weight gain were determined. The striatal content of reactive oxygen species (ROS), reduced glutathione (GSH), ascorbic acid (AA), and protein carbonyl as well as catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST) activities was determined 24 h after the last dose of 3-NP. Na(+)/ K(+)-ATPase, succinate dehydrogenase (SDH), and δ-aminolevulinic dehydratase (δ-ALA-D) activities were also determined. The results demonstrated that ebselen at a dose of 25 mg/kg, but not at 10 mg/kg, protected against (1) a decrease in locomotor activity, motor coordination impairment, and body weight loss; (2) striatal oxidative damage, which was characterized by an increase in ROS levels, protein carbonyl content, and GR activity, an inhibition of CAT and GPx activities, and a decrease in GSH levels; and (3) an inhibition of SDH and Na(+)/K(+)-ATPase activities, induced by 3-NP. GST activity and AA levels were not modified by ebselen or 3-NP. Ebselen was not effective against the inhibition of δ-ALA-D activity induced by 3-NP. The results revealed a significant correlation between SDH activity and ROS levels, and SDH activity and latency to fall (rotarod test). The present study highlighted the protective effect of ebselen against 3-NP-induced toxicity in rats.