Study Of Lead Exposure On Copper Related Proteins Of Rats

Objectives To explore the change of copper related proteins including copper bindingenzyme and copper chaperone on the development of lead toxicity through etime-effectslead rat model. Our finding will provide a basis to enrich mechanism of lead toxicity aswell as the biomarker of lead induced nerve injury.Methods64healthy male SD rats, weighing180~220g, were randomly divided intocontrol group and lead exposure group. Rats in control group were gotten drinking watercontaining0.05%sodium acetate and rats in lead exposure group were given drinkingwater with0.05%lead acetate. The exposure periods were2,4,6,8weeks.8rats weresacrificed form each control and lead exposure group for corresponding experiment test.Rats were observed mental status, activity, diet and measured body weight. Neurologicaltests were performed at2,4,6,8weeks after lead exposure, including functional testssuch as tail flick test sensory, motor function tests such as limb supporting forceexperiments, learning and memory tests (Morrize water maze test) and gait score. ICP-MS was used to detect the content of lead and copper content in tissues including serum,cerebrospinal fluid, bone stock, cortex, choroid plexus, and hippocampus). ELISA wasused to detect superoxide dismutase Cu/ZnSOD, CP ceruloplasmin activity andmonoamine oxidase levels of MAO-B in serum, and hippocampus. Meanwhile, ELISAwas used to also detect copper chaperone including CCS, COX17and ATOX1. The real-time PCR method was appled to detect CCS, COX17and ATOX1mRNA expression inhippocampus. Experiment data were expressed as mean±standard deviation (x±s).SPSS13.0statistical software was used to perform statistical analysis and the statisticmethod including t test, one-way ANOVA, LSD test and correlation. P<0.05indicatestatistical significance.Results1The gait score of rats in2,4,6,8weeks lead exposure increased comparedwith the corresponding control group. Meanwhile, Compared with the control group, thefirst four weeks of lead exposure group started until the first eight weeks, flick thepassage of time rats have significantly prolonged trend over time, the difference wasstatistically significance (P<0.05); The distance of hind limb of lead-exposed rat groupshowed an increasing trend as exposure time increasing. The potency time to findingplatform increased of rat at6week lead exposure, and the difference was statisticallysignificant (P<0.05).2After lead exposure, Lead content in different tissues dramatically increased including the cortex, hippocampus, cerebrospinal fluid, choroid plexus, bonelead levels with increasing exposure time. To our interesting, The increase lead inchoroid plexus was on the top compared with other tissues.3After lead exposure atdifferent time points, copper levels of in the hippocampus choroid plexus increasedand it was showed an increasing trends with lead exposure time prolonged4Comparedwith the control group, MAO-B levels in hippocampus of rats in lead exposure group riseat first two weeks, and then reduced24.69%,31.73%and40.09%at4,6and8weekslead exposure (P<0.05). From2weeks after lead exposure, the activities of CP inhippocampus decreased52.24%,55.13%and70.83%and Cu/Zn-SOD was16.64%、21.22%和35.79%fold decrease at4,6and8weeks lead exposure (P<0.05). At2and4week lead exposure time point,MAO-B in the serum levels were higher than that incontrol group and reduced at6and8weeks lead exposure, the difference wasstatistically significant (P<0.05). The activities of CP, Cu/Zn-SOD in the lead-exposedpoint has declined in a time-dependent manner with prolonged exposure time.5Compared with the control group, CCS content in hippocampus increased at2and4week lead exposure time point and then decreased until8weeks. Moreover, The contentof COX17, ATOX1content in hippocampus of lead-exposed time point increased withlead exposure prolonged and9.21%和44.59%fold increase compared with the controlgroup.Meanwhile, the CCS and COX17levels in serum were increased of at2and4weeks lead exposed (P<0.05)and then reduced until8weeks. Serum ATOX1contentswere1.2,1.44,1.56and1.62fold than that of control group at2,4,8weeks leadexposure.6The CCS, COX17and ATOX1mRNA expression of hippocampus in rats ofthe lead-exposed group increased. At6weeks lead exposure, the difference wasstatistically significant (P<0.05). The CCS, COX17and ATOX1mRNA expressionswere2.07,1.91,1.98folds of that of control group and1.95,2.33,1.69fold at8weekslead exposure.Conclusion Lead exposure dose lead to in copper-related proteins changes, and thencause copper homeostasis disorders, which may involved in lead neurotoxicity.