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.

Hepatorenal protective effect of nano-curcumin against nano‑copper oxide-mediated toxicity in rats: Behavioral performance, antioxidant, anti-inflammatory, apoptosis, and histopathology

BACKGROUND

Metal oxide nanoparticles (NPs) induce oxidative stress that can cause cellular toxicity. A natural antioxidant that can be used to protect tissues from oxidative stress is curcumin.

PURPOSE

In the present study, we evaluated the protective effect of curcumin nanoparticles (curcumin-NPs) against copper oxide nanoparticles (CuO-NPs)-mediated hepatorenal effects on behavioral performance, biochemical markers, antioxidants, inflammation, apoptosis, and histopathology in rats.

STUDY DESIGN

Twenty Wistar adult male rats were randomly divided into four groups (n = 5); Group Ι served as a control, group ΙΙ was orally gavaged with curcumin-NPs (100 mg/Kg), group ΙΙI orally received CuO-NPs (100 mg/kg), and group ΙV received both CuO-NPs and curcumin-NPs orally for 14 days.

METHODS

Behavioral performance, biochemical markers, antioxidants, inflammatory mediators, and apoptotic gene expression were evaluated in addition to histopathological and immunohistochemical examination.

RESULTS

The results revealed that rats exposed to CuO-NPs suffered from behavioral alterations and hepatic and renal damages, which indicated by a marked elevation of serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, urea, uric acid, and creatinine and a decline of total protein. Moreover, there was a significant downregulation in the expression of antioxidants genes, whereas inflammatory mediators expression were upregulated. The histopathological and immunohistochemical examination also corroborated these findings. In contrast, rats co-treated with curcumin-NPs exhibited better behavioral performance, biochemical profile, gene expression, histological architecture, and immunohistochemical staining results.

CONCLUSION

These findings strongly indicated that curcumin-NPs exert significant protection against the behavioral and hepatorenal disorders induced by CuO-NPs toxicity by modulating oxidative stress regulators and gene expression.

Melatonin Ameliorates Cadmium-Induced Affective and Cognitive Impairments and Hippocampal Oxidative Stress in Rat

The present work aims to evaluate the effect of melatonin (Mel) on affective and cognitive disorders induced by chronic exposure to Cadmium (Cd). Male and female Wistar rats received either an intraperitoneal injection of saline solution NaCl (0.9%), Mel (4 mg/kg), Cd (1 mg/kg), or Cd (1 mg/kg) + Mel (4 mg/kg) for 8 weeks. Behavioral disorders were evaluated by different tests mainly the open field and elevated plus maze tests for anxiety-like behavior, forced swimming test (FST) for depression-like behavior, and the Y-maze and Morris water maze (MWM) tests for cognitive disorders. Thereafter, oxidative stress indices and histology of the hippocampus were evaluated. The results confirm that Cd administration has anxiogenic-like effects in both anxiety tests and depressive-like effects in the FST and leads to memory and learning disabilities in the Y-maze and MWM. We also report that Mel counteracts these neurobehavioral disorders. Biochemical assays showed that rats intoxicated with Cd significantly increased levels of nitric oxide (NO) and lipid peroxidation (LPO), while the activities of catalase (CAT) and superoxide dismutase (SOD) were significantly decreased in the hippocampus. In contrast, Mel administration attenuates the Cd-induced changes. The histopathological studies in the hippocampus of rats also supported that Mel markedly reduced the Cd-induced neuronal loss in CA3 sub-region. Overall, our results suggest that Mel could be used to protect against Cd-induced neurobehavioral changes via its antioxidant properties in the hippocampus. The effects of Cd and Mel are sex-dependent, knowing that Cd is more harmful in males, while Mel is more protective in females.

Neuroprotective effect of melatonin on nickel-induced affective and cognitive disorders and oxidative damage in rats

The present work is carried out to explore the neuroprotective potential of Melatonin(Mel), on Ni-induced neurobehavioral, biochemical and histological alterations in male and female rats. The rats were intraperitoneally administered by nickel chloride (NiCl2, 1 mg/kg) and Mel (4 mg/kg) for 60 days. A neurobehavioral assessment was performed. Biochemical determinations of oxidative stress (OS) levels, and histological analysis of hippocampal tissues were also performed. Results showed that Nickel (Ni) treatment increased anxiety-like and depression-like behavior in rats. Besides, cognitive behavior on the Morris water maze was compromised following Ni treatment. Alongside this, Ni elevated hippocampal OS markers like lipid peroxidation and nitric oxide formation with a decrease in superoxide dismutase and catalase activities. Histological observations confirmed these results. Significantly, Mel administration alleviated neurobehavioral changes in Ni-treated rats of both genders. Also, Mel attenuated Ni-induced OS and increased the activities of antioxidant enzymes. The histopathological studies in the hippocampus supported that Mel markedly reduced the Ni-induced neuronal loss. In conclusion, this study suggests that Mel has a neuroprotective effect against Ni-induced neurobehavioral alterations, which may be related to lowering OS in the hippocampus.

Melatonin modulates copper-induced anxiety-like, depression-like and memory impairments by acting on hippocampal oxidative stress in rat

Copper (Cu) is a heavy metal with the ability to induce, at high levels, neurobehavioral alterations, and oxidative stress (OS). On the other hand, melatonin (Mel) is a neurohormone that protects neurons from OS and has a modulatory effect on several behavioral processes. The present experiment was aimed to examine the effect of Mel treatment on Cu-induced anxiety-like, depression-like behaviors, memory impairment, and OS in hippocampus. Herein, adult Wistar rats of both genders received daily Mel (4 mg/kg) thirty minutes before CuCl₂ (1 mg/kg), by intraperitoneal injections for 8 weeks. After the administration period, all rats were submitted to the behavioral tests. Thereafter, OS parameters and histology of the hippocampus were evaluated. The results demonstrate that Mel treatment attenuated Cu-induced anxiety-like and depression-like behaviors, and it improved memory deficits Cu-treated rats. Furthermore, Mel attenuated Cu-provoked OS by reducing lipid peroxidation (LPO) and nitric oxide (NO) levels and enhancing superoxide dismutase (SOD) and catalase (CAT) activities in the hippocampus. The histopathological analysis also supported these results. In conclusion, these findings show that Mel treatment exerted neuroprotective effects against Cu-induced neurobehavioral changes which may be related to reduction of hippocampal OS. Besides, the effects of Cu and Mel were gender dependent, being more marked in females compared to male rats.

Chronic copper exposure leads to hippocampus oxidative stress and impaired learning and memory in male and female rats

Environmental and occupational exposures to copper (Cu) play a pivotal role in the etiology of some neurological diseases and reduced cognitive functions. However, the precise mechanisms of its effects on cognitive function have not been yet thoroughly established. In our study, we aimed to investigate the behavior and neurochemical alterations in hippocampus of male and female rats, chronically exposed to copper chloride (CuCl2) and the possible involvement of oxidative stress. Twenty-four rats, for each gender, were divided into control and three test groups (n = 6), and were injected intraperitoneally with saline (0.9% NaCl) or CuCl2 (0.25 mg/kg, 0.5 mg/kg and 1 mg/kg) for 8 weeks. After the treatment period, Y-maze test was used for the evaluation of spatial working memory and the Morris Water Maze (MWM) to test the spatial learning and memory. Biochemical determination of oxidative stress levels in hippocampus was performed. The main results of the present work are working memory impairment in spatial Y-maze which induced by higher Cu intake (1 mg/kg) in male and female rats. Also, In the MWM test, the spatial learning and memory were significantly impaired in rats treated with Cu at dose of 1 mg/kg. Additionally, markers of oxidative stress such as catalase, superoxide dismutase, lipid peroxidation products and nitric oxide levels were significantly altered following Cu treatments. These data propose that compromised behavior following Cu exposure is associated with increase in oxidative stress.

Protective effect of methylene blue against copper oxide nanoparticle-induced neurobehavioral toxicity

Increasing attention has been paid in the past decade to assessing the toxicological effects of nanoparticles and finding a protectant; thus, the current study aimed to investigate the protective effect of the mitochondria-targeting drug methylene blue (MB) against copper oxide nanoparticle (CuO-NP)-induced neurobehavioral toxicity in rats. For this purpose, twenty rats were allocated to four equal groups (n = 5). The negative control group received distilled water intraperitoneally (IP) and Tween 80 (10 %) orally. The CuO-NP group was given a dose of 100 mg/kg of CuO-NPs, administered orally, and the positive control group was treated with 1 mg/kg MB intraperitoneally (IP). The final group was concurrently exposed to CuO-NPs and MB for 14 consecutive days. At the end of the study, each group was neurobehaviorally blind tested relative to other experimental animals, then brain tissue markers were determined and a histopathological examination was conducted. The results showed that supplementation with CuO-NPs induced neurobehavioral alterations; increased Cu content in the brain; and enhanced lipid peroxidation (malondialdehyde [MDA]), protein peroxidation (protein carbonyl [PC]), and DNA oxidative damage (8-hydroxy-2-deoxyguanosine [8-OH-dG]) compared to other treatments. In addition, a decrease was noted in the mitochondrial dehydrogenases' (aldehyde dehydrogenase 2 [ALDH2], and glutamate dehydrogenase [GDH]) activity in Cu-exposed rats. The histopathological findings revealed shrunken, pyknotic, and hypereosinophic cortical neurons and increased immune positive brown staining of caspase-3 protein, indicating apoptosis. Co-treatment with methylene blue ameliorated the neurotoxic effects of CuO-NPs; therefore, MB evidently had a powerful modulatory effect against the neurotoxicity of nano-Cu oxide via its antioxidant and mitochondrial protection properties.