NMDA receptors mediate synaptic plasticity impairment of hippocampal neurons due to arsenic exposure

Memantine Alleviates PTSD-like Symptoms and Improves Dendritic Arborization through Modulation of the HPA Axis and Neuroinflammation in Rats

Post-traumatic stress disorder (PTSD) poses significant neurological and psychiatric challenges. Investigations into the glutamatergic system, particularly the N-methyl-D-aspartate (NMDA) receptor, are crucial for understanding PTSD mechanisms. This study aimed to evaluate the therapeutic potential of the non-competitive NMDA receptor antagonist memantine in mitigating PTSD symptoms and to explore its underlying cellular and molecular impacts. Male Sprague Dawley rats were subjected to inescapable foot shock stress (FS-stress) to model PTSD. Following stress exposure, memantine was administered at doses of 5 mg/kg and 10 mg/kg six hours post-stress. Behavioural assessments, including fear conditioning and sucrose preference tests, were conducted. Golgi-Cox staining was used to assess neuroanatomical changes related to synaptic plasticity. Western blotting was used to analyse molecular markers associated with synaptic plasticity, while immunoassays measured proinflammatory cytokines and cortisol levels. Memantine treatment improved behavioral outcomes, restoring sucrose preference and reducing freezing behavior. Morphological analysis demonstrated that memantine enhanced dendritic spine structure, particularly increasing the proportion of mature mushroom spines, which are critical for synaptic stability. Additionally, memantine normalized cortisol levels, suggesting a regulatory effect on the hypothalamic-pituitary-adrenal (HPA) axis. Additionally, memantine treatment improved the inflammatory cytokine profile, reducing IL-6 and TNF-α levels. These results suggest that memantine has potential as a therapeutic intervention for PTSD by targeting critical pathways involved in stress responses.The findings indicate that memantine, an NMDA receptor antagonist, can counteract behavioral and functional disturbances induced by FS-stress.

Endocrine disrupting effects on morphological synaptic plasticity

Neural regulation of the homeostasis depends on healthy synaptic function. Adaptation of synaptic functions to physiological needs manifests in various forms of synaptic plasticity (SP), regulated by the normal hormonal regulatory circuits. During the past several decades, the hormonal regulation of animal and human organisms have become targets of thousands of chemicals that have the potential to act as agonists or antagonists of the endogenous hormones. As the action mechanism of these endocrine disrupting chemicals (EDCs) came into the focus of research, a growing number of studies suggest that one of the regulatory avenues of hormones, the morphological form of SP, may well be a neural mechanism affected by EDCs. The present review discusses known and potential effects of some of the best known EDCs on morphological synaptic plasticity (MSP). We highlight molecular mechanisms altered by EDCs and indicate the growing need for more research in this area of neuroendocrinology.

Detection of Arsenic(V) by Fluorescence Sensing Based on Chlorin e6-Copper Ion

The high toxicity of arsenic (As) can cause irreversible harm to the environment and human health. In this study, the chlorin e6 (Ce6), which emits fluorescence in the infrared region, was introduced as the luminescence center, and the addition of copper ion (Cu2+) and As(V) provoked a regular change in fluorescence at 652 nm, whereas that of As(III) was 665 nm, which was used to optionally detect Cu2+, arsenic (As(III), and As(V)). The limit of detection (LOD) values were 0.212 μM, 0.089 ppm, and 1.375 ppb for Cu2+, As(III), and As(V), respectively. The developed method can be used to determine Cu2+ and arsenic in water and soil with good sensitivity and selectivity. The 1:1 stoichiometry of Ce6 with Cu2+ was obtained from the Job plot that was developed from UV-visible spectra. The binding constants for Cu2+ and As(V) were established to be 1.248 × 105 M-1 and 2.35 × 1012 M-2, respectively, using B-H (Benesi-Hildebrand) plots. Fluorescence lifetimes, B-H plots, FT-IR, and 1H-NMR were used to postulate the mechanism of Cu2+ fluorescence quenching and As(V) fluorescence restoration and the interactions of the two ions with the Ce6 molecule.

Phosphodiesterase Inhibitors: A Therapeutic Approach for Arsenic- Induced Neurotoxicity

INTRODUCTION

One of the world's most serious health issues is arsenic toxicity. Prolonged consumption of Arsenic contaminated water causes cognitive damage in the developing and adult brain. The present research investigated how sodium arsenite-induced neurotoxicity in SD rats was affected by rolipram, a PDE4 inhibitor, and vinpocetine, a PDE1 inhibitor.

METHODS

The arsenic concentration was determined, which indicates the accumulation of arsenic in blood. The low weight of the brain indicates the adverse effects on the brain, which was significantly improved by rolipram and vinpocetine. Biochemical markers (MDA, GSH, CAT, and SOD) and protein expression of CREB and P-CREB were studied in the hippocampal region of the brain.

RESULTS

The reduced antioxidant activity and elevated levels of inflammation were significantly improved by rolipram and vinpocetine administration. Additionally, rolipram and vinpocetine significantly increased the CREB and P-CREB expression in the hippocampi of rat brains.

CONCLUSION

PDE4 and PDE1 inhibition in arsenic-induced neurotoxicity could be a novel approach and a new drug therapy for arsenic-induced neurotoxicity.

Subchronic Arsenic Exposure Induces Behavioral Impairments and Hippocampal Damage in Rats

This study investigated the effects of subchronic arsenic exposure on behavior, neurological function, and hippocampal damage in rats. Thirty-two male Wistar rats were divided into four groups and exposed to different concentrations of arsenic in their drinking water for 12 weeks, while weekly water intake and body weight were recorded. Various neurobehavioral tests were conducted, evaluating overall activity levels, exploratory behavior, short-term memory, spatial learning and memory, anxiety-like behavior, and depressive-like states. Arsenic levels in urine, serum, and brain tissue were measured, and histopathological analysis assessed hippocampal damage using hematoxylin and eosin staining. The results demonstrated that arsenic exposure did not significantly affect overall activity or exploratory behavior. However, it impaired short-term memory and spatial learning and memory functions. Arsenic-exposed rats exhibited increased anxiety-like behavior and a depressive-like state. Arsenic levels increased dose-dependently in urine, serum, and brain tissue. The histopathological examinations revealed significant hippocampal damage, including neuronal shrinkage, cell proliferation, irregular structure, disordered arrangement, and vacuolation. These findings emphasize the importance of understanding the impact of arsenic exposure on behavior and brain health, highlighting its potential neurological consequences.

Association of maternal metals exposure, metabolites and birth outcomes in newborns: A prospective cohort study

BACKGROUND

Maternal exposure to metals may pose a risk to the health of newborns, however, the underlying mechanisms remain ambiguous. Herein, we aimed to investigate the influence of metals exposure on birth outcomes and reveal the importance of metabolites in the exposure-outcomes association by using metabolomics methods.

METHODS

In our study, 292 mother-pairs were included who were recruited from the affiliated hospitals of Nanjing Medical University between 2006 and 2011. We measured fifteen metals (mercury, lead, vanadium, arsenic, zinc, cadmium, rubidium, copper, cobalt, iron, molybdenum, strontium, thallium, magnesium and calcium) and metabolites in maternal second trimester serums by using inductively coupled plasma mass spectrometry and ultra-high performance liquid chromatography high resolution accurate mass spectrometry, respectively. A multi-step statistical analysis strategy including exposome-wide association study (ExWAS) model, variable selection models and multiple-exposure models were performed to systematically appraise the associations of individual and mixed metals exposure with birth outcomes. Furthermore, differential metabolites that associated with metals exposure and birth outcomes were identified using linear regression models.

RESULTS

Metal's levels in maternal serums ranged from 0.05 μg/L to 1864.76 μg/L. In the ExWAS model, maternal exposure to arsenic was negatively associated with birth weight (β = 188.83; 95% CI: -368.27, -9.39), while maternal mercury exposure showed a positive association (β = 533.65; 95%CI: 179.40, 887.90) with birth weight. Moreover, each unit increase in mercury (1 ng/mL-log transformed) was associated with a 1.82 week-increase (95%CI: 0.85, 2.79) in gestational age. These findings were subsequently validated by variable selection models and multiple exposure models. Metabolomic analysis further revealed the significant role of 3-methyladenine in the relationship between arsenic exposure and birth weight.

CONCLUSION

This study provides new epidemiological evidence indicating the associations of metals exposure and neonatal birth outcomes, and emphasizes the potential role of metabolite biomarkers and their importance in monitoring adverse birth outcomes.