Effect Of Taurine And Dizocilpine Maleate On Methylmercury-Induced Neurotoxicity In Cerebrum Of Rats

Methylmercury is a cumulative environmental pollutant which harm human being health badly and have strong neurotoxicity. The environmental pollution aroused by methylmercury become global problem and have been paied attention to by investigators in all over the world. Thus, many people research the toxicity of methylmercury deeply. However, the neurotoxicity mechanism of methylmercury is also unclear in recent years. The objective of the present study was to observe the effect of taurine and MK-801 on glutamate metabolism disorder, oxidative injure and cell apoptosis induced by methylmercury in central nervous system of Wistar rats and to discuss the relationship of excitotoxicity induced by glutamic abnormal increasing, oxidative injure of cerebrum and apoptosis of nerve cell and to deteimine the antagonism of taurine and MK-801 on the toxicity of methylmercury in order to offer evidences to control and prevent toxicity of methylmercury.MethodsSixty Wistar rats obtained from the Laboratory Animal Center of China Medical University, weight (180±10)gram, were randomly divided into five groups by weight. The rats were adaptability fed a week before experiment. The first group was the control group, the second one was lowdose MeHg-exposed group and the third was highdose MeHg-exposed group, were given 0.9% NaCl. The fourth group was subcutaneously injected with lmmol/kg of taurine and the five group was subcutaneously injected with 0.3μmol/kg of MK-801. Two hours later, the control group was intraperitoneally given 0.9% NaCl, the second group was intraperitoneally given 4μmol/kg of methylmercury chloride, the third, fourth and five groups were given 12μmol/kg of methylmercury chloride. The administration of methylmercury chloride was given five times and taurine and MK-801 were given three times every week for 4 weeks.24 hours after the last injection, the rats were killed and the cerebral cortices were taken for detecting the contents of Hg, Glu, Gln and MDA and the activities of GS, PAG, SOD and GSH-Px and cell apoptosis by Annexin V-FITC-PI in pallium.ResultsThe results showed that after administration 4 weeks, accompanied with the increasing treated methylmercury dosage, the contents of Hg increased in pallium, there was a dose-response relationship among control, lowdose and highdose MeHg groups. Compared with the control group, the contents of Hg in the highdose MeHg-exposed group, taurine group and MK-801 group increased significantly(P<0.01). Compared with highdose MeHg-exposed group, the contents of Hg in the taurine group and MK-801 group were not difference and statistics significance(P>0.05).The results showed that after administration 4 weeks, accompanied with the increasing treated methylmercury dosage, the contents of Glu and MDA increased and Gln decreased and the activities of PAG increased and GS, SOD and GSH-Px decreased and the rate of cell apoptosis increased in pallium, there was a dose-response relationship among control, lowdose and highdose MeHg groups. Compared with highdose MeHg-exposed group, the contents of Glu and MDA decreased significantly and Gln increased significantly and the activities of PAG decreased significantly and GS, SOD and GSH-Px increased significantly and the rate of cell apoptosis decreased significantly in the taurine group and MK-801 group.Conclusions1. After administration four weeks, accompanied with the increasing treated methylmercury dosage, the contents of Glu increased and Gln decreased and the activities of PAG increased and GS decreased in pallium, bring about glutamate metabolism disorder. The contents of MDA increased and the activities of SOD and GSH-Px decreased in pallium, bring about nerve cell oxidative injure and apoptosis.2. The taurine and MK-801 may decrease the contents of Glu and the activities of PAG and increase the contents of Gln and the activities of GS and recover glutamate metabolism gradually in pallium, which suggest that they have a certain protective effect on MeHg-induced neurotoxicity in Wistar rats.3. The taurine and MK-801 may decrease the contents of MDA and increase the the activities of SOD and GSH-Px in pallium, which suggest that they have a certain protective effect on MeHg-induced oxidative injure in Wistar rats.4. The taurine and MK-801 may decrease the rate of nerve cell apoptosis in pallium, which suggest that they have a certain protective effect on MeHg-induced apoptosis in Wistar rats.