The Role Of Synapse Related Protein GAP-43 And SYP In Learning And Memory Disfunction Induced By TMT In Balb/c Mice

Objective: With organotin becoming widely applied as one of the lead-free stabilizer substitute, TMT, the byproduct of organotin production, has therefor been widely exists in production and people's daily life; acute poisoning incident caused by TMT was common, the harmful effects of which has become more and more serious. Previous study showed that TMT exerts hazardous effects on many human organs and systems, especially on central nervous system; numerous studies have been done focusing on nervous system, learning and memory alteration is one of its important research, whereas research on the mechanism of TMT-induced damage of learning and memory ability is few. Our research aims to establish TMT acute poisoning model under at certain experimental dose, and study its neurotoxic effects and the changes of synaptic related proteins through behaviouristics, histology and molecular biology perspectives. Besides, the changes of synaptic related proteins after the administration of related protective agent will also be explored.Method:â‘ 6⁹ weekly Balb/c male mice were divided into saline group(control group) and TMT groups with different dose (2.00, 2.25, 2.50, 2.75, 3.00mg.kg^-1 .k.w), each group received TMT by intraperitoneal injection, and the experimental concentration of TMT were determined by the results of Morris water maze and HE staining, and TMT acute exposure model was established under this dose;â‘¡Western blot test was used to determine GAP-43 and SYP protein expression in hippocampus and cerebral cortex of the Balb/c mice when they were exposed to TMT in different phase (0h, 1h, 3h, 6h, 12h, 24h);â‘¢Mice were divided into several groups including control, TMT, TMT+rutin and rutin groups, the last two groups required rutin pre-treatment (10mg.kg^-1) one week before Morris water maze, and TMT group was administrated with saline from day 1 to 6, behavior changes were evaluated by the value of latency escape, expression of GAP-43 and SYP protein in hippocampus and cerebral cortex of the Balb/c mice were tested by western blot; explore behavioural effects of TMT on mice received rutin pretreatment, and the effects of TMT on synaptic related protein GAP-43 and SYP in those mice, thus studying possible protective role of rutin in TMT-induced learning and memory ability damage of mice.Result:â‘ Mices were conducted Morris water maze test, latency escape of the saline group and TMT (2.00mg.kg^-1)group decreased with training times increasing, and difference of latency escape of two groups were of no statistical significance (P>0.05); latency escape of TMT group (2.25mg.kg^-1 2.75mg.kg^-1) did not decrease during all the four times of training, after the fourth training of water maze, differences of latency escape between TMT(2.25mg.kg^-1) group and control group were significantly lenghthened (P<0.05), from the third training onwards, latency escape of TMT(2.50mg.kg^-1) and (2.75mg.kg^-1) group were lenghthened compared with that of the saline group (P<0.05), when mice in TMT 3.00(mg.kg^-1) group entered into water, water maze experiment could not be successfully conducted; the results of HE staining suggested that necrosis (smaller, shapened cell with hyperchromatic nuclei) of neuron cell in cerebral cortex area of mice occurred 24h after TMT intraperitoneal injection at the dose of (2.0mg.kg^-13.00mg.kg^-1), and necrosis increased with dose increasing; Different extent of necrosis also occurred in hippocampus, cerebellum and other brain regions.â‘¡We can see fom the results of western blot that the expression of GAP-43 protein in hippocampus and cerebellum of TMT group and control group at each phase (0²4h) were of no statistical difference (P>0.05); Whereas the differences of SYP protein in hippocampus between TMT 24h group and saline group were significantly down-regulation(P<0.05), the differences of SYP protein in cerebellum between TMT 6²4h group and saline group were also significantly down-regulation (P<0.05), and the expression of SYP protein decreased with exposing time increasing.â‘¢The result of water maze showed that escape latency of control, rutin, TMT+rutin groups decreased significantly with the training times increasing, escape latency of TMT group did not show any changes during the concessive 8 times of water maze training. From the fourth water maze training onwards, escape latency of TMT was significantly lenghthened compared with saline group (p<0.05), from the fifth onwards, escape latency of TMT was significantly lenghthened compared with TMT+rutin group(p<0.05), from the third water maze training onwards, escape latency of TMT was significantly lenghthened compared with rutin group (p<0.05). It's seemed that escape latency of rutin group was shorter than that of saline group during the same training period, but they were not of statistical significance (P>0.05). The result of western blot showed that the expression of GAP-43 protein in hippocampus and cerebellum of TMT, saline, TMT+rutin, rutin group were of no statistical difference (P>0.05), whereas the expression of SYP in hippocampus and cerebellum of TMT was significantly down-regulation compared with saline, rutin, TMT+rutin groups.(p<0.05)Conclusion:â‘ The escape latency of Balb/c mice was lenghthen induced by TMT(2.25mg.kg^-1) after 24h acute exposure, suggesting that dysfunction of learning and memory ability of mice occurred.â‘¡TMT imposes no influence on expression of synaptic related protein GAP-43 in hippocampus and cerebellum of mice, yet can down-regulate the expression of SYP protein in hippocampus and cerebral cortex, and down-regulation in cerebral cortex occurred much earlier than that in hippocampus.â‘¢24h after acute exposure of TMT(2.25mg.kg^-1)in mice which received rutin pretreatment for 1 week can not prolong the escape latency, suggesting that the protective role of rutin in the TMT-induced learning and memory ability damage.â‘£In this study, rutin pretreatment can not yet influence on expression of GAP-43, but can against down-regulation of SYP expression, the protective effect of rutin on learning and memory ability damage induced by TMT is potentially related to rutin's against down-regulation of SYP protein.