The Role Of MGluR1 In The Mechanism Of Neurotoxicity Induced By Aluminum

[Objective]To investigate the role of mGluR1 in the mechanism of neurotoxicity induced by aluminum in workers , mice and neurocytes exposed to aluminum.[Methods]1. The study on population exposed to aluminum: 1) 35 aluminum electrolytic workers were selected from a state-owned enterprise in Taiyuan City,32 controls unexposed to aluminum occupationally were selected from the same enterprise; 2) Neurobehavioral test battery(NCTB)recommended by WHO and MMSE were conducted in workers and controls; 3) The expression of mGluR1 in prote in levels was detected by Western-blot. 2. The study of aluminum in vivo: 1) 32 C57BL mice, and healthy, were divided into 4 groups at random: normal saline, 5mg/kg Al³⁺, 10mg/kg Al³⁺ and 20mg/kg Al³⁺. They were exposed to AlCl3 by intraperitioneal injection, 90d. After exposure, the Morris water maze test was performed to test the learning and memory abilities of mice;2)â‘ A fter the experiment, s1ices of the cerebral cortex and hippocampus were made and morphological changes were observed by optical microscope;â‘¡The apoptosis rate of hippocampus cells was measured by method of fluorescent analysis;3) The expression of mGluR1 was detected by QRT-PCR and Western blot. 3. The study of aluminum in vitro: 1)Primary neurocytes were cultured by dissociating 1-3 days C57BL mice cerebral cortex ,cell density was adjusted at 1×105cells/ml.After 5 days , neurocytes were divided into 4 groups: 0 mM Al³⁺, 0.5mM Al³⁺, 1mM Al³⁺ and 2mM Al³⁺;â‘ For 48 hours, the cell viability of neurocytes was quantified by method of Cell Counting Kit-8;â‘¡The apoptosis rate of neurocytes was measured by method of fluorescent analysis;2) The expression of mGluR1 in protein levels were detected by Western blot.[Results] 1.The study on population exposed to aluminum: 1) No differences were found in workers on age, gender,length of working, education,smoking, drinking and retired age between Al- exposed workers and controls(Pï¹¥0.05); 2)â‘ the scores of POMSA and POMSF in Al-exposed workers were higher than that of control group(P<0.05),while the scores of POMSC, POMSD, POMST and POMSV in Al-exposed group had no obvious change(P>0.05). The scores of DSPF,DSPB, DSY and PAC were lower than that of control group, while the scores of SRT, SRTS, SRTF, SANP, SANN , BVR and PA had no alteration(P>0.05). This implied that Al-exposure had adverse impact on workers,mood state and neurobehavioral function;â‘¡The score of MMSE, ability of calculation, short-term memory and speech ability in Al-exposed workers were decreased than that of control group(P<0.05),while the orientation force,immediate memory in Al-exposed workers had no alteration(P>0.05);3) The Western-blot demonstrated that mGluR1 expression in protein level was increased after aluminum exposure(P<0.01).2. The study of aluminum in vivo: 1)â‘ The place navigation test, aluminum can make the latency of finding the platform of mice increased obviously (P<0.01), the latency of finding the platform of mice in the low,middle,high-dose group were higher than that of normal saline(P<0.01);â‘¡The spatial probe test, aluminum can make the time of target quadrant stasis of mice decreased obviously (P<0.01), compared with normal saline, the time of target quadrant stasis of mice in the middle,high-dose group were decreased(P<0.05,P<0.01); 2)â‘ Histopathological results: HE staining, in normal saline, the morphosis of mice brain neurocytes was basically normal, lining up in order. The alignment of cells became in disorder with greater dosage of aluminum. In higher dosage group, cell junction got loose, endochylema condensed,anachromasis, karyopyknosis of shrinking somas and ring. Belt appeared around the cells.The amount of the zone without dye, and the cells were increased;â‘¡Using Annexin V and PI, aluminum can make the apoptosis rate of neurocytes in mice's hippocampus increased obviously (P<0.01).Apoptosis rate of neurocytes in mice's hippocampus in 10mmol/L Al³⁺ ,20mmol?L Al³⁺ group were significantly higher than that of normal saline (P<0.05,P<0.01);3) With the dose of aluminum increasing, mGluR1 protein and mGluR1 mRNA increased(P<0.05, P<0.01). Compared with normal saline, mGluR1 protein and mGluR1 mRNA increased(P<0.05, P<0.01). 3 The study of aluminum in vitro: 1)â‘ With the dose of aluminum increasing, the cell viability of neurocytes decreased (P<0.01).Compared with 0mM Al³⁺,the cell viability of neurocytes of 0.5mM Al³⁺,1mM Al³⁺,2mM Al³⁺ decreased (P<0.01) ;â‘¡Using Annexin V and PI ,aluminum can make the apoptosis rate of neurocytes increased (P<0.01).The apoptosis rate of neurocytes in the middle,high-dose group were higher than that of 0mM Al³⁺(P<0.05,P<0.01);2) With the dose of aluminum increasing, mGluR1 protein increased(P<0.01). Compared with 0mM Al³⁺, there existed difference in the middle,high-dose group(P<0.05 ,P<0.01).[Conclusion]The upwards regulation of mGluR1 play a role in the mechanism of neurotoxicity induced by aluminum in workers , mice and neurocytes exposed to aluminum.