牛磺酸对染锰大鼠学习记忆功能和谷氨酸相关代谢酶影响研究

Effects of taurine on spatial study and memory capacity and glutamate related enzymes in rats after manganese exposure

目的探讨牛磺酸对染锰所致大鼠学习记忆功能和谷氨酸相关代谢酶的影响。方法无特定病原体级雄性健康SD大鼠随机分为空白对照组、染锰组、预防组、治疗组和治疗对照组共5组,每组6只。后4组大鼠腹腔注射给药剂量为20 mg/kg体质量的氧化锰,预防组大鼠同时腹腔注射给药剂量为200 mg/kg体质量的牛磺酸,空白对照组大鼠同时腹腔注射等体积无菌生理氯化钠溶液,每日1次,每周5 d,共8周;其后,治疗组大鼠腹腔注射给药剂量为200 mg/kg体质量的牛磺酸,治疗对照组大鼠腹腔注射等体积无菌生理氯化钠溶液,每日1次,每周5 d,共8周。5组大鼠均进行Morris水迷宫实验记录逃避潜伏时间(连续观察5 d,每天训练4次)及平台搜索次数;采用酶联免疫吸附实验测定丘脑谷氨酰胺酶(PAG)、谷氨酸脱羧酶(GAD)和谷氨酰胺合成酶(GS)水平。结果 5组组间逃避潜伏期差异有统计学意义(P<0.01);5个时间点间逃避潜伏期差异有统计学意义(P<0.01);组别与时间无交互作用(P>0.05);染锰组、治疗组和治疗对照组逃避潜伏期均高于空白对照组(P<0.01,P<0.05,P<0.01),预防组逃避潜伏期分别低于染锰组和治疗对照组(P<0.01,P<0.05),但预防组逃避潜伏期分别与空白对照组、治疗组比较,差异均无统计学意义(P>0.05);5个时间点逃避潜伏期两两比较,差异均有统计学意义(P<0.05)。5组组间的平台搜索次数比较,差异无统计学意义(P<0.05)。染锰组PAG和GAD水平均低于空白对照组(P<0.01,P<0.05);预防组PAG、GAD和GS水平均低于空白对照组(P<0.01,P<0.05,P<0.05);预防组PAG、GAD和GS水平分别与染锰组比较,差异均无统计学意义(P>0.05);治疗组GAD、GS水平均高于治疗对照组(P<0.01,P<0.05);治疗组GAD水平高于染锰组(P<0.01)。结论锰可降低大鼠空间学习记忆能力,牛磺酸干预或治疗后可改善其学习记忆能力。牛磺酸干预对染锰大鼠谷氨酸相关代谢酶的调节作用机制有待进一步研究。

Objective To explore the effects of taurine on rats＇ spatial study and memory capacity and metabolic enzymes related to glutamate after manganese exposure. Methods Specific pathogen free SD rats were randomly divided into 5 groups, a blank group, a MnC12 exposure group, a prevention group, a treatment group and a treatment control group with 6 rats in each group. All rats except those in the last 4 groups were intraperitoneally injected with MnC12 · 4H2O at the dose of 20 mg/kg bw. The preventing rats were also intraperitoneally injected with taurine at the dose of 200 mg/kg bw at the same time. The rats in the blank group were intraperitoneally injected with saline once a day, 5 days a week for 8 weeks. The rats in the treatment group were later intraperitoneally treated with taurine at 200 mg/kg bw once a day, 5 days a week for 8 weeks. Escape latency and platforms searches with Morris water maze experiment were tested in all rats （ training 4 times a day for 5 consecutive days ）. Thalamie phosphate activated glutaminase （PAG）, glutamie acid decarboxylase （ GAD ） and glutamine synthetase （ GS ） levels were determined with enzyme-linked immunosorbent experimental. Results The differences of escape latency among 5 groups were statistically significant （ P 〈 0. 01 ） , and the differences among 5 time points of latency were statistically significant （P 〈 0. 01 ） ; without category and time interactions （P 〉 0. 05 ） ; the incuba-tion periods in MnC12 exposure group, treatment group and control group were higher than that in the blank group （P 〈 0. 01, P〈0. 05,P 〈 0. 01 ）. Escape latency period in the prevention group was respectively lower than those of MnC1z exposure group and treatment group （ P 〈 0. 01, P 〈 0. 05 ）, but no statistical significant differences were found （ P 〉 0. 05）, compared with the blank and the treatment group. Paired comparison showed that significant differences were ob- served on 5 time points of incubation period （P 〈 0. 05 ）.. There was no statistical significant difference on platforms sear- ches among 5 groups. PAG and GAD in MnC12 exposure group were lower than those of the blank group （ P 〈 0. 01, P 〈 0. 05） ; PAG, GAD and GS in prevention group were lower than those in the blank group （P 〈 0. O1, P 〈 0. 05, P 〈 0. 05 ）, while PAG, GAD, and GS levels in prevention group, compared with MnC12 exposure group, showed no statistical significant difference （P 〉0. 05）. GAD and GS levels in treatment group were higher than those of the treatment control group （P 〈0. 01, P 〈0. 05）. GAD level of treatment group was higher than that in MnC12 exposure group （P 〈0. 01 ）. Conclusion Manganese reduces the spatial learning and memory ability of rats, taurine intervention or treatment can im- prove their ability of learning and memory. The mechanism of taurine intervention on glutamic acid related metabolic en- zymes in manganese exposed rats needs further research.