2,4-滴丁酯染毒对大鼠学习记忆行为及氨基酸类神经递质含量的影响
Effects of Butyl 2,4-Dichlorophenoxyacetate Exposure on Learning and Memory Behavior and Levels of Amino Acid Neurotransmitters in Rats
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摘要:
目的 探讨2,4-滴丁酯90 d 染毒对雄性大鼠学习记忆行为及大脑皮质、海马组织中氨基酸类神经递质含量的影响。 方法 将40 只健康30 d 龄SPF 级雄性Wistar 大鼠随机分为4 组,分别为对照组(玉米油:蒸馏水体积比为1:1)和2,4-滴丁酯低(1/100 LD50,6 mg/kg)、2,4-滴丁酯中(3/100 LD50,18 mg/kg)、2,4-滴丁酯高(6/100 LD50,36 mg/kg)剂量组,每组10 只。经口灌胃染毒,每周连续染毒5 d,实验周期为90 d。染毒第4、8、13 周进行Morris 水迷宫测试大鼠的学习记忆能力。染毒结束后,高效液相色谱法检测大鼠大脑皮质、海马中谷氨酸、天门冬氨酸、γ-氨基丁酸、甘氨酸的含量。 结果 Morris 水迷宫测试第13 周时,随染毒剂量升高,大鼠平均逃避潜伏期逐渐延长(P<0.05),呈剂量-效应关系(r=0.961 1,P<0.01)。随着2,4-滴丁酯染毒剂量的升高,大鼠大脑皮质中谷氨酸水平呈升高趋势(P<0.05)、γ-氨基丁酸水平呈下降趋势(P<0.05),均呈剂量-效应关系(r=0.942 5,r=-0.887 2,均P<0.01);天门冬氨酸含量在高剂量组升高显著(P<0.05)。海马中谷氨酸含量、天门冬氨酸含量均呈升高趋势(P<0.05)、γ-氨基丁酸含量呈下降趋势(P<0.05),均呈剂量-效应关系(r=0.970 1,r=0.886 6,r=-0.916 2,均P<0.01)。 结论 2,4-滴丁酯亚慢性染毒影响大鼠学习记忆能力及大鼠脑组织氨基酸类神经递质水平。 Abstract:Objective To study the effects of 90 d butyl 2, 4-dichlorophenoxyacetate (2, 4-D b.e.) exposure on learning and memory behavior and levels of amino acid neurotransmitters in rats' pallium and hippocampi． Methods A total of 40 healthy 30-day-old Wistar male rats (SPF grade) were divided into four groups at random: control group (corn oil:distilled water=1:1) and 2, 4-D b.e. low, middle, and high dose experimental groups (at doses of 6, 18, and 36 mg/kg, representing 1/100 LD50, 3/100 LD50, and 6/100 LD50 respectively), 10 in each group. Administration by gavage was performed 5 times a week for 90 d. After 4, 8, and 13 weeks, Morris water maze test was used to evaluate the learning and memory abilities of rats. At the end of the study, the animals were decapitated to determine the contents of glutamate, asparaginic acid, gamma amino butyric acid, and glycine in pallium and hippocampi by high performance liquid chromatography. Results After 13 weeks, the results of Morris water maze demonstrated that the mean escape latency increased with higher concentrations of 2, 4-D b.e. (P<0.05) in a dose-effect manner (r=0.961 1,P<0.01). With the concentration of 2, 4-D b.e. increasing, in pallium the level of glutamate showed a rising tendency (P<0.05), the level of gamma amino butyric acid showed a falling tendency (P<0.05), both in a dose-effect relationship (r=0.942 5,r=-0.887 2, bothP<0.01); and the content of asparaginic acid in the high dose group was significantly elevated (P<0.05). In hippocampi the contents of both glutamate and asparaginic acid showed an increasing tendency (P<0.05), whereas the content of gamma amino butyric acid showed a falling tendency (P<0.05), all displaying a dose-effect relationship (r=0.970 1,r=0.886 6,r=-0.916 2, all P<0.01). Conclusion Sub-chronic 2, 4-D b.e. exposure could affect the learning and memory ability and the levels of ammo acid neurotransmitters in brain tissues of rats.
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