[Effect of lead exposure on the accumulation of copper and iron in central nervous system of rats].

Objective: To investigate the dynamic changes of copper and iron contents in brain tissue, body fluids and barriers of rats exposed to lead at different periods in order to provide a theoretical basis for the study of the mechanism of lead nerve injury. Methods: Sixty-four healthy adult SPF male SD rats were randomly divided into control group and lead exposure group, after one week of adaptive feeding, rats in the lead exposure group were treated with 250 mg/L lead acetate, and rats in control group were treated with ordinary drinking water, the experimental period was 12 weeks. After exposure for 3, 6, 9 and 12 weeks, the samples including blood, choroid plexus, cerebrospinal fluid, cortex, hippocampus, striatum, hypothalamus, amygdala, substantia nigra and cerebellum were obtained. Lead, copper and iron content in all kinds of samples were detected by Inductively Coupled Plasma Mass Spectrometry(ICP-MS). The measurement data were presented as Mean±SD , Comparison of metal contents in different tissues of rats at different time analyzed using repeated measurement analysis of variance, Two-variable correlation analysis using Spearman correlation test.The relationship between lead exposure experiod and copper and iron in samples was studied by using trend test. Results: After 12 weeks of lead exposure compared with the control group, lead contents in cortex, hippocampus, striatum, hypothalamus, amygdala, substantia nigra and cerebellum of rats were 2.21, 2.44, 2.95, 3.53, 4.01, 1.85 and 2.86 folds of control group, and the differences were statistically significant( P <0.05). At the same time, lead content in blood, cerebrospinal fluid,choroid plexus, brain microvessels and bones increased. The increase rate in the amygdala and cerebrospinal fluid ranked first among brain tissue or barrier,which were 4.01 and 3.0 folds respectively. Compared with the control group, Compared with the control group, copper content in cortex,hippocampus, striatum, hypothalamus,amygdala, cerebellum,blood,cerebrospinal fluid,choroid plexus and cerebral microvasculature showed an increasing trend among rats following 3,6,9,12 weeks of lead exposure. Copper content change in the striatum was highest among all brain tissue. The increase rate of copper content in the striatum was at the top among brain tissues. After 12 weeks of lead exposure,copper content in brain microvessels was 4.98 folds higher than that of the control group ( P <0.05). After lead exposure at different periods,the iron content in the cortex, hippocampus, striatum,cerebrospinal fluid,choroid plexus and brain microvessels of experimental rats all increased( P <0.05). And the iron increase rate in the hypothalamus or cerebrospinal fluid increase ranked first among brain tissues or body fluid the most obviously. Conclusion: With the increase of exposure time, lead exposure can changes in the contents of copper and iron in different brain tissues,body fluids and barriers in rats,among which, the contents of copper and iron in the amygdala,cerebrospinal fluid and brain microvessels increase significantly. This may be related to nerve damage from lead exposure.