高功率微波辐射对大鼠脑内神经递质及全身儿茶酚胺代谢的影响

Changes of neurotransmitters and catecholamine metabolites in rats exposed to high power microwave

目的:观察高功率微波辐射对大鼠脑内氨基酸类神经递质及全身儿茶酚胺代谢的影响。方法:实验于2004-09/12解放军军事医学科学院放射与辐射医学研究所实验病理研究室完成。选择6～8周二级雄性Wistar大鼠60只,随机抽签法分为假辐射组(n=10)和辐射组(n=50)。辐射组按照辐射剂量分为3mW/cm2亚组(n=10)、10mW/cm2亚组(n=20)、30mW/cm2亚组(n=10)和100mW/cm2亚组(n=10)。采用0,3,10,30和100mW/cm2高功率微波辐射大鼠,于辐射后6h、1d和7d活杀取材,通过高效液相色谱仪检测大脑皮质、海马和丘脑中谷氨酸、天冬氨酸、γ-氨基丁酸和甘氨酸4种氨基酸的含量以及尿中香草扁桃酸和高香草酸含量的变化。结果:参加实验大鼠60只,均进入结果分析。①高功率微波辐射后6h大鼠不同脑区氨基酸类神经递质含量的变化:大脑皮质,10mW/cm2组谷氨酸及γ-氨基丁酸含量升高,谷氨酸/γ-氨基丁酸比值降低;海马3～100mW/cm2组谷氨酸含量均显著降低。丘脑中4种氨基酸含量无明显改变。②高功率微波10mW/cm2辐射不同时间后大鼠不同脑区氨基酸类神经递质含量的变化:辐射后6h大脑皮质谷氨酸含量升高,1d后基本恢复正常;γ-氨基丁酸含量明显升高,1d后有所恢复,7d时仍未恢复正常;谷氨酸/γ-氨基丁酸比值显著降低,1d后有所恢复,7d时仍未恢复正常。海马内谷氨酸含量明显降低;甘氨酸含量在辐射后6h明显降低,1d时基本恢复。丘脑氨基酸含量无明显改变。③高功率微波辐射后尿中儿茶酚胺代谢产物含量的变化:辐射后3d,10mW/cm2组尿中香草扁桃酸含量显著升高,30和100mW/cm2组显著降低;10mW/cm2组尿中高香草酸含量于显著降低;而100mW/cm2组显著升高。结论:高功率微波辐射可引起大鼠氨基酸类和儿茶酚胺类神经递质代谢紊乱,大脑皮质和丘脑均可见主要兴奋性和抑制性氨基酸含量升高,二者比值下降,提示兴奋性氨基酸参与了大脑皮质和丘脑的早期损伤,而抑制性氨基酸则与其病变恢复有关。海马兴奋性氨基酸含量及谷氨酸/γ-氨基丁酸比值均降低,提示海马神经元的兴奋性降低,可能与学习记忆能力的降低密切相关。

AIM： To observe the effect on amino acid neurotransmitters in the brain and the catecholamine （CA） metabolites in the total body of rats after exposed to high power microwave （HPM）. METHODS： The experiment was conducted at the Experimental Laboratory of Pathology, Institute of Radiation Medicine, Academy of Military Medical Sciences from September to December in 2004. Sixty male Wistar rats of 6-8 months old were randomly divided into sham group （n=10） and radiation group （n=50）. According to the radiation dose, the radiation group was reassigned to 4 subgroups： subgroup A （n=10, 3 mW/cm^2）, subgroup B （n=20. 10 mW/cm^2）, subgroup C （n=10, 30 mW/cm^2） and subgroup D （n=10. 100 roW/cm^2）. The rats were exposed to HPM at the 0. 3, 10, 30 and 100 mW/cm^2, and sacrificed at 6 hours. 1 clay and 7 days after the exposure. The contents of four amino acids [glutamic acid （Glu）, asparagic acid （Asp）, gamma-alninobutyric acid （GABA） aud glucine （Gly）] in the pallium, hippocampus and thalamencephalon, and the changes of vanillylmandelic acid （VMA） and homovanillic acid （HVA） contents in the urine were examined with the high performance liquid chromatography （HPLC） method. RESULTS： Totally 60 experimental rats were involved in the result analysis. ①The changes of amino acid ncurotransmitters ill different brain regions after the HPM exposure： Only at 10 mW/cm^2, the contents of Glu and GABA increased, while the ratio of Glu/GABA decreased in the pallium： And the Glu content decreased markedly in the hippocampus at 3- 100mW/cm^2; No apparellt chauges of four amino acid contents were found in the thalamencephalon. ②The changes of amino acid neurotransmitters in various hrain regions at different time points： At 6 hours after HPM exposure, Glu content in the pallium increased and resumed at 1 day; GABA content increased apparently and returned partly at 1 day, but was still uncommon at 7 days alter exposure. GIu/GABA ratio was reduced markedly, recovered a little at 1 day and still abnormal at 7 days. In the hippocampus, the Glu content decreased apparently; While the Gly content decreased apparently at 6 hours and resumed at I day, No obvious changes of amino acid appeared in the thalamencephalon.③The changes of CA metabolite content in the urine after HPM exposure： The content of VMA notably increased in the urine of 10mW/cm^2 and decreased in 30 and 100 mW/cm^2 at 3 clays after HPM exposure; The content of HVA decreased in the urine of 10 mW/cm^2 and increased in 100 mW/cm^2 at 3 days after HPM exposure. CONCLUSION： The exposure of HPM confuses the metabolism of neuro-transmitters of amino acids anti catecholamine. In the pallium and thalameneephalon, hoth excitorv and depressive amino acid contents increase, and their ratio decrease, which suggests that the excitory take part in the early injury of pallium and thalamencephalon while the depressive are connected with the recovery. The excitory amino acid content and the ratio of Glu/GABA decrease in the hippoeampus, which indicates that the lower excitability in the hippocampus is con-elated with the decreased learning and metnory ahility.