| Objective:(1)To explore the impact of occupational aluminum exposure on cognitive functions,peripheral lymphocytes NMDAR and group I mGluRs,and to find the possibility that lymphocytes glutamate receptors act as surrogate biomarkers for change of cognitive functions;(2)To explore the coincidence change tendency of NMDAR and group I m GluRs between cortex and peripheral lymphocytes.Methods:1.In occupational epidemiology study:1)Using cluster sampling,121 electrolytic aluminum workers and 231 thermoelectric workers and support staff were selected.Using questionnaire to collect fundamental data,and analyzing cognitive functions by neuropsychological scale,the scale include: MMSE,CDT,FOM,VFT,DST(DSF and DSB).2)Using graphite furnace(GFAAS)to determine aluminum concentration in plasma,which was taken as internal exposure.Lymphocytes NMDAR and group I mGluRs were measured by ELISA.2.In vivo study:1)32 healthy and male SD rats were selected,and randomly divided into control,low,medium,high aluminum dose groups according to body weight,each group drunk normal saline,20 mg/L,120 mg/L,720 mg/L AlCl3 solution respectively for 360 days.At the end of experiment,learning and memory functions of rats were evaluated by Morris Water Maze.2)Aluminum in plasma and cortex were determined by GFAAS,and gene expression of NMDAR and group I mGluRs were analyzed by real-time polymerase chain reaction(RT-PCR)and agarose gel electrophoresis(AGE).The glutamate receptors proteins were determined by ELISA.Results:1.In occupational epidemiology study:1)All objects were divided into control,low,medium,high Al dose group based on plasma aluminum concentration and type of work.The plasma aluminum concentrations were 58.15(10.10,88.36),113.19(88.84,139.24),167.43(139.30,203.69),254.62(205.69,374.55)?g/L respectively.The difference of plasma aluminum concentration among groups were statistically significant(P<0.05).2)Analysis of fundamental data: All objects were male,then theirage,working years,the degree of education,the level of personal average income,smoking and drinking were compared,all of those had no statistical difference among groups(P>0.05),The comparison of results of neuropsychological tests and cognitive functions tests showed that the score of MMSE,CDT,FOM had no statistical difference among groups(P>0.05),however,the score of DST,DSF,DSB,VFT had significantly difference among groups(P<0.05).Then multi-dimension analysis of MMSE suggested that the score of memory was statistically significant(P<0.05).Then Stepwise regression analysis showed that plasma aluminum,education and age are main influence factors in cognitive function.3)The result of lymphocytes glutamate receptors proteins: With the increasing of plasma aluminum,NMDAR1 and NMDAR2 A expression were declining(P<0.05),the receptors in high plasma aluminum concentration group were significantly lower than those in control group(P<0.05).mGluR1 protein increased with increased plasma aluminum concentration.Then,NMDAR2 B and mGluR5 showed no statistically difference among groups(P>0.05).4)The results of correlation analysis among plasma aluminum concentration,glutamate receptors expression and cognitive functions: NMDAR1 and NMDAR2 A showed negative correlation with plasma aluminum concentration,the correlation coefficient were-0.475,-0.692 respectively(P<0.05).mGluR1 showed positive correlation,r=0.756(P<0.05).Then,NMDAR1 had positive correlation with DSF,DSB,DST,VFT,correlation coefficient were 0.213,0.249,0.271,0.228 respectively(P<0.05).NMDAR2 A had positive correlation with VFT,r=0.206(P<0.05),but correlation coefficient with DSF,DSB,DST were 0.070,0.071,0.084(P>0.05).The correlation coefficient between mGluR1 and DSF,DSF,DSB,VFT were-0.026?0.039?0.005?-0.114(P>0.05).5)Objects divided by plasma aluminum,education and age and compared NMDAR1 and NMDAR2 A among groups,both of them did not show statistical difference among education level and age.But with increasing of plasma aluminum,NMDAR1 and NMDAR2 A declined.2.In vivo study:1)Navigation test indicated that,escape latent period shortened with increase of learning time,however,escape latent period extended with increase of aluminum dose(P<0.05).The escape latent period of high dose group was longer than control and low dose groups(P<0.05).In spatial probe test,compared with control group,times across the platform significantly decreased in each group(P<0.05),and resident time of target quadrant significantly shortened(P<0.05),which was lower in high dose group than those in control and low dose groups(P<0.05).2)The results of aluminum concentration in plasma and cortex: The difference of aluminum both in plasma and cortex were statistically significant(P<0.05).3)The gene expression of cortex showed that,with the increasing of aluminum concentration,NMDAR1 was decrease and the difference among medium,high dose groups and control group were statistically significant(P<0.05),then,NMDAR2 A,NMDAR2B,mGluR1,mGluR5 also showed decline tendency.The gene expression of lymphocytes showed that,the gene expression of NMDAR1 in medium,high dose groups were lower than those in control and low dose groups(P<0.05).The NMDAR1 protein in cortex in high dose group was significantly lower than those in control and low dose groups(P<0.05).And NMDAR1 protein of lymphocytes in medium,high dose groups were lower than those in control and low dose groups(P<0.05).The correlation coefficient of NMDAR1 between rat cortex and lymphocytes was 0.646(P<0.05).The expression of NMDAR2 A,NMDAR2B,mGluR1,mGluR5 genes had not observed.Conclusions:1.Occupational aluminum exposure for long term may impair cognitive functions,especially short-term memory;2.NMDAR1,NMDAR2 A,mGluR1 protein in human lymphocytes had a remarkable correlation with plasma aluminum concentration,and NMDAR1,NMDAR2 A expression had a significant correlation with cognitive functions,both of NMDAR1,NMDAR2 A can be taken as surrogate biomarker for further research;3.Chronic aluminum exposure had impact on learning and memory functions of rats.With increasing of aluminum dose,NMDAR1 protein in cortex and lymphocytes were decreasing,and there were better correlation between them.Then we can take NMDAR1 as biomarker of learning and memory functions for further study;Howoever,the correlations between NMDAR2 A,NMDAR2B,mGluR1,mGluR5 in cortex and lymphocytes failed to be verified. |
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