ABSTRACT
Objective@#To investigate the influence of occupational aluminum exposure on cognitive function and glutamate receptor protein expression in peripheral blood lymphocytes in workers and the possibility of glutamate receptor being used as a biomarker for cognitive impairment in aluminum workers.@*Methods@#From October to December, 2014, cluster sampling was performed to select 121 workers in aluminum electrolysis workshop as exposure group and 231 workers in thermoelectric workshop and logistics department as control group. Mini-Mental State Examination, clock drawing test, digit span test (DST) , verbal fluency test (VFT) , and Fuld Object-Memory (FOM) Evaluation were used to analyze cognitive function. Graphite furnace atomic absorption spectrophotometry was used to measure plasma aluminum level as an exposure indicator. Enzyme-linked immunosorbent assay was used to measure the content of glutamate receptor proteins in peripheral blood lymphocytes, including the subunits of N-methyl-D-aspartate receptor NR1, NR2A, and NR2B and metabotropic glutamate receptor 1 (mGluR1) . The correlation between cognitive function indices and the content of glutamate receptor proteins was analyzed.@*Results@#There was no significant difference in plasma aluminum level between the control group and the exposure group (132.52±80.40 μg/L vs 182.88±72.32 μg/L, P>0.05) . According to the plasma aluminum level, the study subjects were divided into control group and low-, medium-, and high-level plasma aluminum groups, and there were significant differences in plasma aluminum level between these groups (all P<0.01) . The high-level plasma aluminum group had a significantly lower memory ability score than the control group and the low- and medium-level plasma aluminum groups (all P<0.05) . The high-level plasma aluminum group had lower DST and digital span forward (DSF) scores than the control group and the low-and medium-level plasma aluminum groups. The low-, medium-, and high-level plasma aluminum groups had lower digital span backward (DSB) scores than the control group. The medium-and high-level plasma aluminum groups had lower VFT scores than the control group and the low-level plasma aluminum group. The high-level plasma aluminum group had significantly lower expression of NR1 and NR2A proteins than the control group and the low-and medium-level plasma aluminum groups, and the medium- and high-level plasma aluminum groups had significantly higher expression of mGluR1 protein than the control group and the low-level plasma aluminum group (all P<0.05) . The expression of NR1 and NR2A proteins was negatively correlated with plasma aluminum level (r=-0.475 and -0.692, both P<0.05) , andthe expression of mGluR1 protein was positively correlated with plasma aluminum level (r=0.756, P<0.05) . The expression of NR1 protein was positively correlated with DSF, DSB, DST, and VFT scores (rs=0.213, 0.249, 0.271, and 0.228, all P<0.05) , and the expression of NR2A protein was positively correlated with VFT score (rs=0.206, P<0.05) .@*Conclusion@#Occupational aluminum exposure may affect workers’ memory function, and the expression of NR1 and NR2A in peripheral blood lymphocytes is correlated with cognitive function indices and can be used as biomarkers for cognitive impairment in aluminum workers.
ABSTRACT
<p><b>OBJECTIVE</b>In this research, we have observed changes of PHF8、H3K9me2、BDNF, and their regulatory roles in changing the amplitude value of LTP in hippocampus due to aluminum exposure so that we can discuss the impact on the learning and memory that caused by chronic aluminum exposure.</p><p><b>METHODS</b>Forty healthy SPF grade SD male rats were randomly divided into four groups by weight, including control group and low, medium, high dose aluminum exposed group, each group had 10 rats. The exposed rats drank water containing different doses of aluminum chloride (AlCl3) (2、12、72 mg/kg Al(3+)) for 90 d. We measured LTP in hippocampus by electrophysiological grapier and detected the expression of PHF8、H3K9me2、BDNF by western-blot.</p><p><b>RESULTS</b>Electrophysiological measurements shows that compared with that of control group, the average of fEPSPs was decreased at different time points in all exposed groups (P<0.01) . The results of western-bolt test demonstrated that the expression of PHF8 in the exposed groups were significantly lower than those of control group (P<0.01) . And the expression the of H3K9me2 of medium and high dose groups were significantly higher than control group (P<0.05) . While the expression of BDNF of medium and high dose groups were decreased compared with the control group (P<0.05) .</p><p><b>CONCLUSION</b>Chronic aluminum exposure can reduce the LTP via the route of PHF8-H3K9me2-BDNF in the hippocampus of rats, which then may impair the ability of learning and memory.</p>