Intrahippocampal Effects of Nickel Injection on the Affective and Cognitive Response in Wistar Rat: Potential Role of Oxidative Stress

Evaluation of Heavy Metals and Essential Minerals in the Hair of Children with Autism Spectrum Disorder and Their Association with Symptom Severity

The exact cause of Autism spectrum disorder (ASD) remains unclear. The accumulation of heavy metals and the imbalance of trace elements are believed to play a key role in the pathogenesis of ASD. This study aimed to compare the levels of trace elements and heavy metals in the hair of 1-16-year-old children with varying ASD severity. We included a control group of 57 children, as well as 124 children with autism, consisting of 53 with mild to moderate autism and 71 with severe autism. Questionnaires and hair samples were collected, and 21 chemical elements were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Children with severe autism showed significantly higher levels of the trace elements copper (Cu) and heavy metals vanadium (V), cobalt (Co), nickel (Ni), arsenic (As), cadmium (Cd), and lead (Pb) in their bodies compared to the control group. Boys with severe autism showed significantly higher levels of Cu, As, Cd, and Pb compared to the control group, while girls with severe autism exhibited significantly lower levels of potassium (K) and increased levels of Pb. Severely autistic children under 7 years old had significantly increased levels of Mn, Cu, V, Co, Ni, As, Cd, and Pb. Children with severe autism aged 7-16 years typically showed significantly higher levels of Cu and As. These findings underscore the importance of heavy metals and essential minerals as environmental factors in the severity of ASD disease.

A prospective study of a whole blood metal mixture and depressive symptoms among Black women from Detroit, Michigan

Exposure to metals has been previously associated with depressive symptoms, but few studies have considered potential effects of metal mixtures. In addition, few previous studies have been conducted among Black women, who are disproportionately at risk for exposure to some metals and greater depression incidence and severity. We analyzed data from the Study of Environment, Lifestyle, and Fibroids (SELF), a prospective cohort study of reproductive-aged Black women from Detroit, to examine associations between a mixture of metals, metalloids, and trace elements ("metals") and depressive symptoms (n = 1450). SELF participants self-identified as Black or African American and were 23-34 years of age at enrollment. We collected covariate information on structured questionnaires and whole blood samples at baseline. We quantified 17 metals in whole blood using inductively coupled plasma mass spectrometer triple quadruple or Direct Mercury Analyzer-80. Participants reported depressive symptoms on the Center for Epidemiologic Studies Depression Scale (CES-D) at the 20-month follow-up visit, where higher CES-D scores reflected greater depressive symptoms. We used quantile-based g-computation to estimate the cumulative association of the metal mixture with CES-D scores, adjusting for age, household income, educational attainment, body mass index, smoking status, alcohol intake, and parity. We estimated beta coefficients (with 95 % confidence intervals [CI]) as the percent difference in CES-D scores per quartile increase in all metals. A one-quartile increase in the metal mixture was associated with 14.8 % lower (95 % CI=-26.7 %, -1.1 %) CES-D scores, reflecting lower depressive symptoms. The mixture association was driven by nickel, copper, cesium, molybdenum, and lead. Other neurotoxic metals (cadmium, arsenic, mercury, chromium) were associated with greater depressive symptoms. Findings from this study suggest that exposure to a mixture of metals may affect depressive symptoms in Black women, with individual metals acting in opposing directions.

Effects of Nickel Bioaccumulation on Hematological, Biochemical, Immune Responses, Neuroinflammatory, Oxidative Stress Parameters, and Neurotoxicity in Rats

Nickel (Ni) exposure is linked to numerous health issues, including dermatitis, immunotoxicity, and cancer. Emerging evidence suggests Ni may cross the blood-brain barrier, accumulating in the brain and causing neuroinflammation, oxidative stress, and neuronal apoptosis. Herein, we investigated the effect of Ni exposure through the intraperitoneal route, studying the Ni effect in subacute and chronic toxicity, on various health parameters in Wistar rats. Rats were randomly divided into four groups (n = 10 per group): two groups received a daily intraperitoneal injection of NiCl₂ at a dose of 0.25 mg/kg for subacute (21 days) or chronic (60 days) exposure periods, while the other two groups were treated with NaCl solution (0.9%) as a control for equivalent durations. The study assessed behavioral, biochemical, hematological, immunological, neurobiochemical, and histopathological effects over 21 and 60 days. Neurobehavioral tests, blood and tissue analyses, and organ examinations were conducted. This study demonstrates that Ni bioaccumulation in subacute and chronic exposure has significant health impacts in Wistar rats, including hematological, immunological, biochemical, AchE activity, neuroinflammatory, oxidative stress, and neurobehavioral changes. Chronic exposure results in higher Ni accumulation, particularly in the brain, causing neurotoxicity, inflammation, and behavioral disorders such as anxiety, depression, and memory impairment. The findings highlight the importance of limiting Ni exposure to prevent adverse health effects.

Subchronic Exposure to Mixture of Cadmium, Copper, and Nickel Induces Neurobehavioral Deficits and Hippocampal Oxidative Stress of Wistar Rats

The present study was aimed at evaluating the influence of the subchronic exposure of cadmium (Cd), copper (Cu), and nickel (Ni) mixtures on affective behaviors, memory impairment, and oxidative stress (OS) in the hippocampus. Thirty male Wistar rats were divided into 5 equal groups. Group 1 (control) received a saline solution (NaCl 0.9%). Groups 2, 3, and 4 received Cd (0.25 mg/kg), Cu (0.5 mg/kg), and Ni (0.25 mg/kg), respectively, while group 5 received a Cd, Cu, and Ni mixture through intraperitoneal injections for 2 months. After the exposure period, all rats were submitted to behavioral tests. Subsequently, OS markers and histological changes in the rats' hippocampi were assessed. Results showed that a 2-month exposure to the mixtures of metals (MM) has led to higher anxiety-like and depression-like behaviors and cognitive deficits in rats when compared to the control group and the individual metals. Furthermore, the MM induced heightened OS, evidenced by the rise in lipid peroxidation and nitric oxide levels. These effects were accompanied by a decrease in superoxide dismutase and catalase activities in the hippocampus. The histopathological analysis also supported that MM caused a neuronal loss in the CA3 sub-region. Overall, this study underscores that subchronic exposure to the Cd, Cu, and Ni mixture induces an OS status and histological changes in the hippocampus, with important affective and cognitive behavior variations in rats.

Melatonin attenuates affective disorders and cognitive deficits induced by perinatal exposure to a glyphosate-based herbicide via antioxidant pathway in adult male and female rats

The massive use of herbicides, particularly glyphosate-based herbicides (GBHs), raises several worries, notably their neurotoxic effects. Several studies have explored the consequences of developmental exposure. Our work aims to determine the impact of maternal exposure to GBH on behavioral disorders and memory deficits, as well as the involvement of oxidative stress in the hippocampus and prefrontal cortex. In addition, our study explores the neuroprotective properties of melatonin in male and female offspring. Pregnant Wistar rats were injected with GBH 75 mg/kg during gestation and lactation. After weaning, the offspring were treated with melatonin (4 mg/kg) from postnatal days 30-58. Our results show that GBH increases anxiety-like behavior levels in offspring, as well as depression-like behavior. GBH also impairs working memory in progeny. While markers of oxidative stress show a disturbance in lipid peroxidation and catalase activity, with a more pronounced effect in females, on the other hand, melatonin considerably attenuated the neurotoxic impact observed in the offspring, with higher efficacy in females. The oxidative stress results confirm the antioxidant power of melatonin to counteract the damaging effects of exposure to environmental contaminants such as glyphosate-based pesticides. It will then be interesting to further our work to fully understand the sex-dependent effect of melatonin.

Exploring the neuroprotective role of melatonin against nickel-induced neurotoxicity in the left hippocampus

Previous studies have demonstrated that the hippocampus, a crucial region for memory and cognitive functions, is particularly vulnerable to adverse effects of exposure to heavy metals. Nickel (Ni) is a neurotoxic agent that, primarily induces oxidative stress, a process known to contribute to cellular damage, which consequently affects neurological functions. The antioxidant properties of melatonin are a promising option for preventing the adverse effects of Ni, especially by protecting cells against oxidative stress and related damage. In our investigation of the potential neuroprotective effects of melatonin against Ni-induced neurotoxicity, we chose to administer melatonin through intraperitoneal injection in rats following an intrahippocampal injection of Ni into the left hippocampus. This approach allows us a targeted investigation into the influence of melatonin on the neurotoxic effects of Ni, particularly within the crucial context of the hippocampus. In the present study, we demonstrated that melatonin efficiency reduced lactate dehydrogenase level, and preserved antioxidant enzyme activities in Ni-exposed hippocampal tissue. It also mitigated the decline in superoxide dismutase and catalase activities. On the other hand, melatonin could act directly by reducing reactive oxygen species Ni-induced overproduction. Taking to gather these two potential mechanisms of action could be responsible for the adverse effect of Ni on the behavioral alteration observed in our study. This study provides significant insights into the potential of melatonin to mitigate the detrimental effects of Ni on the brain, particularly into the hippocampal region, suggesting its possible implications for the treatment of neurological disorders related to Ni exposure.

Melatonin is a Neuroprotective and Antioxidant Agent against Neurotoxicity Induced by an Intrahippocampal Injection of Nickel in Rats

The investigation into the hippocampal function and its response to heavy metal exposure is crucial for understanding the mechanisms underlying neurotoxicity, this can potentially inform strategies for mitigating the adverse effects associated with heavy metal exposure. Melatonin is an essential neuromodulator known for its efficacy as an antioxidant. In this study, we aimed to determine whether melatonin could protect against Nickel (Ni) neurotoxicity. To achieve this, we performed an intracerebral injection of Ni (300 µM NiCl2) into the right hippocampus of male Wistar rats, followed by melatonin treatment. Based on neurobehavioral and neurobiochemical assessments, our results demonstrate that melatonin efficiently enhances Ni-induced behavioral dysfunction and cognitive impairment. Specifically, melatonin treatment positively influences anxious behavior, significantly reduces immobility time in the forced swim test (FST), and improves learning and spatial memory abilities. Moreover, neurobiochemical assays revealed that melatonin treatment modulates the Ni-induced alterations in oxidative stress balance by increasing antioxidant enzyme activities, such as superoxide dismutase (SOD) and catalase (CAT). Additionally, we observed that melatonin significantly attenuated the increased levels of lipid peroxidation (LPO) and nitric oxide (NO). In conclusion, the data from this study suggests that melatonin attenuates oxidative stress, which is the primary mechanism responsible for Ni-induced neurotoxicity. Considering that the hippocampus is the main structure involved in the pathology associated with heavy metal intoxication, such as Ni, these findings underscore the potential therapeutic efficacy of melatonin in mitigating heavy metal-induced brain damage.

Potential Role of Oxidative Stress in the Effects of Chronic Administration of Iron on Affective and Cognitive Behavior on Male Wistar Rat

In this work, we studied the impact of chronic iron exposure, in the form of iron sulfate (FeSo4), on affective and cognitive disorders and oxidative stress in the male Wistar rat. The treatment was carried out for 8 weeks, the rats received an intraperitoneal injection of iron at different doses: 0.25, 0.5, and 1 mg/kg. Affective and cognitive disorders are assessed in open field test (OFT), elevated plus maze (EPM), forced swimming test (FST), Morris water maze (MWM), and Y-maze. The hippocampus and prefrontal cortex of each animal were taken for biochemical examination. Our results show that iron exerts anxiogenic and depressogenic effects, which were observed first at the dose of 0.5 mg/kg and continued in a dose-dependent manner up to the maximum tested dose of 1 mg/kg. According to results from the MWM and Y-maze tests, continuous exposure to iron induces cognitive disorders that are defined by the disturbance of working memory and influences spatial learning performance causing a deficit of spatial memory retention. We noted that chronic exposure to iron can be associated with the appearance of a state of oxidative stress in the hippocampus and the prefrontal cortex demonstrated by an increase in lipid peroxidation, an increase in nitric oxide, and also by disturbances in the antioxidant defense systems following a determination of the concentrations of catalase. In conclusion, we can deduce from this work that chronic iron exposure can be related to the induction of cognitive and affective disorders and oxidative stress.

Mechanistic considerations and biomarkers level in nickel-induced neurodegenerative diseases: An updated systematic review

The environment has been implicated to be a strong determinant of brain health with higher risk of neurodegeneration. The drastic rise in the prevalence of neurodegenerative diseases (NDDs) including Alzheimer's disease (AD), Parkinson's disease (PD), autism spectrum disorder (ASD), multiple sclerosis (MS) etc., supports the idea that environmental factors may play a major role in NDDs aetiology. Nickel is one of the listed environmental metals reported to pose a serious threat to human health. This paper reported available studies on nickel level in NDDs covering both animal and human studies. Different databases were searched for articles reporting the main neurotoxicity mechanisms and the concentration of nickel in fluids and tissues of NDDs patients compared to controls. Data were extracted and synthesized by ensuring the articles were related to nickel and NDDs. Various mechanisms were reported as oxidative stress, disturbances in mitochondrial membrane potential, trace elements homeostasis destabilization, etc. Nickel was found elevated in biological fluids as blood, serum/plasma and CSF and in the brain of NDDs, as a consequence of unintentional exposure thorough nickel-contaminated air, food, water, and skin contact. In addition, after exposure to nickel, the concentration of markers of lipid peroxidation were increased, while some antioxidant defence systems decreased. Thus, the reduction in the exposure to nickel contaminant may hold a promise in reducing the incidence of NDDs.

Metabolomics analysis of the effects of quercetin on renal toxicity induced by cadmium exposure in rats

This study aims to explore the protective effects of quercetin against cadmium-induced nephrotoxicity utilizing metabolomics methods. Male Sprague-Dawley rats were randomly assigned to six groups: control, different dosages of quercetin (10 and 50 mg/kg·bw, respectively), CdCl2 (4.89 mg/kg·bw) and different dosages quercetin plus CdCl2 groups. After 12 weeks, the kidneys were collected for metabolomics analysis and histopathology examination. In total, 11 metabolites were confirmed, the intensities of which significantly changed (up-regulated or down-regulated) compared with the control group (p < 0.00067). These metabolites include xanthosine, uric acid (UA), guanidinosuccinic acid (GSA), hypoxanthine (Hyp), 12-hydroxyeicosatetraenoic acid (tetranor 12-HETE), taurocholic acid (TCA), hydroxyphenylacetylglycine (HPAG), deoxyinosine (DI), ATP, formiminoglutamic acid (FIGLU) and arachidonic acid (AA). When high-dose quercetin and cadmium were given to rats concurrently, the intensities of above metabolites significantly restored (p < 0.0033 or p < 0.00067). The results showed quercetin attenuated Cd-induced nephrotoxicity by regulating the metabolism of lipids, amino acids, and purine, inhibiting oxidative stress, and protecting kidney functions.