Possible role of selenium in ameliorating lead-induced neurotoxicity in the cerebrum of adult male rats: an experimental study

Associations among blood heavy metals, neurofilament light chains and cognition function in US adults: NHANES 2013-2014

BACKGROUND

Heavy metals could induce neurotoxicity, leading to cognitive function and motor deficiencies. Serum neurofilament light chain (sNfL) is a promising biomarker for neurological injury, and it may indicate nerve damage from heavy metals exposure. However, there's limited research exploring the associations among heavy metals, sNfL, and cognitive function in adults, and the existing findings are inconsistent.

OBJECTIVE

959 participants were enrolled from the National Health and Nutrition Examination Surveys (NHANES) 2013-2014. This study was aimed to investigate the possible associations among heavy metals, sNfL, and cognitive function in adults.

METHODS

We utilized data from the National Health and Nutrition Examination Survey (NHANES) 2013-2014, comprising 959 participants. Heavy metals were detected in blood samples including lead (Pb), cadmium (Cd), mercury (Hg), manganese (Mn), and selenium (Se), with measurements taken using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technology. The level of sNfL was quantified via an innovative high-throughput immunoassay technology developed by Siemens Healthineers. Cognitive function were assessed using the Animal Fluency Test (AFT), the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), and the Digit Number Symbol Substitution Test (DSST). Additionally, generalized linear models (GLMs), weighted quantile sum regression (WQS), Bayesian kernel machine regression (BKMR), quantile-based g computation (qgcomp), and restricted cubic splines (RCS) analyses were employed to examine the associations between heavy metals exposure and sNfL level. Finally, a mediation analysis to explore the interaction among heavy metals, sNfL, and cognitive function in adults aged 60 and above.

RESULTS

The generalized linear models exhibited a positive correlation between blood Pb or Cd levels and sNfL (β = 0.14, 95 % CI: 0.08-0.20; β = 0.14, 95 % CI: 0.07-0.20), in total population. Both WQS and BKMR analysis consistently showed a strong correlation between higher levels of the blood heavy metals mixture and increased sNfL (OR=0.051, 95 %CI: 0.025-0.090). The qgcomp model indicated that Cd had a significant positive correlation with sNfL, while Mn and Se showed a significant negative correlation with sNfL. Moreover, we have identified a significant relationship between sNfL or Cd and cognitive function scores (AFT, DSST) in adults aged 60 and above. The mediation analysis further revealed that sNfL partially mediated the relationship between Cd and AFT or DSST scores, with interpretive efficiencies of 23.35 % and 32.7 %, respectively.

CONCLUSION

This study is the first to utilize sNfL data to establish a link between heavy metals exposure and cognitive function. The finding highlight the the positive correlation between Pb or Cd and sNfL, the negative correlation between Se and sNfL. The impact of Cd exposure on cognitive function in individuals older than 60 was partially explained by sNfL. Further investigations are required to validate these findings, considering the constraints of the NHANES study.

L-arginine mitigates choroid plexus changes in Alzheimer's disease rat model via oxidative/inflammatory burden and behavioral modulation

Aging is a risk factor for Alzheimer's disease (AD), leading to choroid plexus (CP) alterations. This study aimed to explore the possible therapeutic mechanisms of ARG on AD-induced CP changes. Sprague-Dawley rats were divided into 6 groups (n = 7 per group): adult, adult+ARG, aged, aged+ARG, aged+AD, and aged+AD+ARG groups. Evaluations were for Y-maze test, serum levels of oxidative/inflammatory markers, and serum and cerebrospinal fluid (CSF) markers of AD, histopathology, immunohistochemistry, and histomorphometry. The aged+AD group demonstrated a significant decline in maze test parameters, total antioxidant capacity (TAC), brain-derived neurotrophic factor (BDNF) levels, and vascular endothelial growth factor (VEGF) immunoexpression, while tumour necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β), beta-amyloid (Aβ) levels and amyloid protein precursor (APP), and heat shock protein90 (HSP90) immunoexpressions were significantly increased. Sections of this group showed flat epitheliocytes, congested capillaries, connective tissue expansion, and degenerated endothelium. These parameters were modulated by ARG administration, via increased levels of TAC (1.37 vs 2.17 mmol/L), (p = 0.018) BDNF (serum: 48.50 vs 78.41; CSF: 4.07 vs 7.11 pg/ml) (p< 0.001), and VEGF (0.07 vs 0.26 OD) (p< 0.001), in addition to decreased levels of TNF-α (86.63 vs 41.39 pg/ml) (p< 0.001), IL-1β (96.04 vs 39.57 pg/ml) (p< 0.001), Aβ (serum: 67.40 vs 47.30; CSF: 189.26 vs 169.84 pg/ml) (p< 0.001), and HSP90 (0.54 vs 0.13 OD) (p< 0.001). In conclusion, ARG ameliorates the AD-associated CP changes, including histopathological, oxidative/inflammatory, and AD markers, and VEGF and HSP90 immunohistochemical alterations. Dietary ARG consumption is recommended to avoid AD progression in the elderly.

Biosorption and Bioprotective Potential of Levilactobacillus brevis in Mice Challenged by Lead-Induced Oxidative Stress

Lead (Pb) poisoning is a widespread issue in both developed and developing countries that poses a significant public health challenge. Our study aimed to explore the impact of Levilactobacillus brevis strains on inflammatory and antioxidant gene expression in the liver and brain of mice exposed to oxidative stress caused by Pb. We began by evaluating Pb absorption by Levilactobacillus brevis strains (ARKA-CH-1 (A1) and ARKA-CH-6 (A6)) using the inductively coupled plasma mass spectrometry (ICP-MS) in vitro to identify the most effective strain. We then divided four groups of BALB/c mice into control and experimental groups and treated them for 30 days. The control group received a normal diet, while the experimental groups consumed lead-containing water (0.6 g/L) with or without Levilactobacillus brevis strains. Following the experiments, we collected blood samples to test liver markers, antioxidant enzymes, and immunoglobulins. We also used real-time PCR to examine the expression of superoxide dismutase (SOD) and inducible nitric oxide synthase (iNOS) genes. The results showed that the A1 strain was the most effective in absorbing Pb. The Pb exposure led to an increase in liver enzyme values and a decrease in antioxidant enzyme activity and immunoglobulin factors. However, the combination of A1 and A6 strains had a greater effect in reducing inflammatory enzymes and increasing antioxidant enzymes. Furthermore, we observed a significant increase in iNOS gene expression and a notable decrease in SOD gene expression with Pb consumption. However, the combination of A1 and A6 strains had a synergistic effect in reducing iNOS and increasing SOD gene expression. In conclusion, Levilactobacillus brevis A1 strain alone or in combination with the A6 strain could be a promising strategy to mitigate the oxidative stress symptoms in mice challenged by lead-induced toxicity.