Association of blood lead levels with neurobehavior and BDNF expression in school going children

BACKGROUND

Childhood Lead (Pb) toxicity has been an ongoing concern for decades; however, its underlying pathogenesis remains unclear. Although its prevalence has come down in developed countries (USA, Europe); it is relatively high in low to middle-income countries of South-East Asia. The current study aimed to evaluate the association of blood lead levels (BLLs) with neurobehavioral alterations and changes in Brain-Derived Neurotropic Factor (BDNF) expression in Indian school children.

METHODOLOGY

School going children in age group of 9-15 years (N = 72) were included in the study. Neurobehavioral changes were assessed using Childhood Psychopathological Measurement Schedule (CPMS) and BLL were measured by Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS). BDNF mRNA expression and serum BDNF levels were assessed by Real-Time PCR and ELISA, respectively.

RESULTS

Median BLL was 4.95 μg/dL (IQR = 4.47), very close to the recommended toxic cut off levels (<5 μg/dL). BLLs had a direct correlation with both CPMS scores and BDNF expression. Depression was found to be significantly higher in boys than in girls with high BLLs. BDNF mRNA expression and serum BDNF levels were higher among children with high BLL, although not to significant levels.

CONCLUSION

We report a significant association of neurobehavioral changes with the prevalence of high Pb levels in Indian children. Additionally significant correlation of BDNF with BLL in these children suggests a causal role of BDNF in Pb induced neurological damage.

Association Between Circulating Plasmacytoid Dendritic Cell Percentage and Blood Lead Levels in Children

Lead (Pb) exposure is known to cause T helper 1 (Th1) to T helper 2 (Th2) shift in the immune response. The mechanism responsible for these effects is unclear. Plasmacytoid dendritic cells (pDCs) are known as the principal secretor of type 1 interferons (IFNs), which have a stimulatory effect on Th1 differentiation. However, no previous study has explored the effect of Pb on pDCs. Thus, the present study was conducted to explore the correlation between circulating pDC count, serum IFNα (pan) levels, and blood lead levels (BLLs) in children environmentally exposed to Pb. A total of 82 school-going children were recruited from government and private schools in Jodhpur. BLL, pDC percentages, and serum IFNα (pan) levels were estimated by atomic absorption spectrometry, flow cytometry, and ELISA, respectively, in 82 samples. The participants were divided as per BLL quartiles into 4 groups: (A) BLL < 3 μg/dL (n = 21), (B) BLL = 3-4.08 μg/dL (n = 20), (C) BLL = 4.08-6.17 μg/dL (n = 20), and (D) BLL > 6.17 μg/dL (n = 21). Only in category D, pDC percentages showed a significant positive correlation with BLL (Spearman's R = 0.5). Therefore, this preliminary data suggests that BLL might modulate pDC levels in a dose-dependent manner.

Association of blood lead level with neurobehavior and neurotransmitter expressions in Indian children

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BLL had a significant direct correlation with abnormal neurobehavior.

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Serum serotonin levels were significantly lower in children with high blood lead levels (BLL).

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Serum serotonin and dopamine receptor expression were upregulated in children with high BLL.

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Serum serotonin levels had significant negative association with adverse neurobehavior.

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Dopamine receptor expression had significant positive association with adverse neurobehavior.

Present study aimed to assess the alterations in neurotransmitter expression and its association with Blood Lead Level (BLL) and neurobehavioral pattern in children. 72 school going children were recruited. Blood lead levels were determined by Atomic Absorption Spectrophotometer. Neurobehavioral state was assessed by means of population specific scale i.e. CPMS (Childhood Psychopathological measurement Schedule). Serum serotonin and dopamine were estimated by ELISA, receptor and transporter gene expressions were assessed by quantitative real time PCR. Significant positive correlation was observed between Total CPMS score (i.e. adverse neurobehaviour) and BLL. Further, serum serotonin levels and dopamine receptor expression showed a negative and positive association with BLL, respectively. In similarity, serum serotonin levels showed a negative correlation and dopamine receptor expression had a significant positive correlation with total CPMS score. Environmental exposure to Lead (Pb) may result in significant alterations in the neurotransmitter levels which may be associated with neurobehavioral changes in the children exposed to Pb.