Objective: To study the impact of the chronic aluminum exposure on Nmethyl-D-aspartate receptor 1( NMDAR1) in the cortex and peripheral blood, and to explore the possibility that whether NMDAR1 of peripheral blood lymphocytes could be taken as a biomarker of aluminum exposure.
Methods: Thirty-two cleaning degree, healthy and male SD rats were randomly divided into four groups by weight, i. e. controlgroup, low-dose group, mid-dose group, and high-dose group separately. Different doses of Al Cl3( 20, 120 and 720 mg /kg) were added into the rats' drinking water, and control group was given tap water, each rat approximately drink 10 m L /100 g, the experiment lasted 360 days. Then, plasma aluminum and cortex aluminum were measured by atom absorption spectrometry with graphite furnace( GFAAS), relative expression of NMDAR1 gene was assayed by real-time fluorescence quantitative polymerase chain reaction( RTPCR) and NMDAR1 protein both in the cortex and peripheral blood lymphocytes were assayed by enzyme-linked immunosorbent( ELISA).
Results: Plasma aluminum increased with the increase of Al exposure dose( P < 0. 05), the result of plasma aluminum were69. 88, 83. 10, 87. 06 and 134. 60 μg / L, respectively, plasma aluminum in low-dose, mid-dose and high-dose group were significant increased, compared to the control group. Cortex aluminum increased with the increasing of aluminum dose( P < 0. 05), the result of cortex aluminum were 0. 065, 0. 102, 0. 139 and 0. 228 μg / mg, respectively. The differences among groups were significant( P < 0. 05). The expression of NMDAR1 gene both in the cortex and peripheral blood lymphocytes were reduced with the increasing of aluminum dose( P < 0. 05). The differences of gene expression in the cortex among the three groups were significant statistically( P < 0. 05). The differences of gene expression in peripheral blood lymphocytes among the three groups were significant statistically( P <0. 05), but there was no significantly statistical difference between mid- and high-dose group( P = 0. 167). The protein level of NMDAR1 in the cortex was obviously reduced in high-dose group, compared to that in the control and low-dose group( P < 0. 05). The protein level of NMDAR1 in the peripheral blood lymphocytes were significantly reduced, compared to that in the control and low-dose group( P < 0. 05), the protein level of NMDAR1 in the peripheral blood lymphocytes in the mid- and high-dose group was not different from one another( P = 0. 159).
Conclusion: Chronic aluminum exposure could severely impaire the gene expression and protein expression of NMDAR1 both in the cortex and peripheral blood lymphocytes. With the increasing of the aluminum dose, gene expression and protein expression of NMDAR1 are decreased. The NMDAR1 could be taken as a peripheral biomarker of aluminum exposure for further research.
Keywords: N-methyl-D-aspartate receptor 1; aluminum exposure; cortex; lymphocytes.