Aim Toinvestigatetheeffectofhigh,me-dium and low doses of Mahuang decoction on the re-lease amount of rat hippocampal neural transmitter (Glu,Gly,Asp,GABA),then compare Mahuang de-contion with ephedra alkaloids and ephedra.Methods Ratswererandomlydividedinto6groupsandgiven orally with Mahuang decoction of high dose (calculated by ephedra 4 g·kg-1 ),medium dose (calculated by ephedra 2 g·kg-1 ),low dose (calculated by ephedra 1 g · kg-1 ),ephedra (calculated by ephedra 2 g · kg-1 ),ephedra alkaloids (ephedrine 7 mg · kg-1 , pseudoephedrine 2. 4 mg · kg-1 , methylephedrine 1. 12 mg · kg-1 )and blank control group.Samples were obtained from the hippocampus of conscious rat by microdialysis sampling technique.The content of ami-no acid neurotransmitters in dialysates was detected u-sing the established HPLC-ECD with OPA pre-column derivationmethod.Results Fouraminoacidneuro-transmitters could be well separated in 28 min.High, medium and low doses of Mahuang decoction,ephedra and ephedra alkaloids significantly increased the con-tent of these four amino acid neurotransmitters,com-pared with blank control group (P<0. 05 ).Ephedra alkaloids significantly reduced the levels of inhibitoryamino acid neurotransmitters GABA and Gly in 90 min,compared with the medium dose of Mahuang de-coction.Excitatory neurotransmitters of ASP and Glu in hippocampus showed the trend of increase first and then decrease after oral administration of Mahuang de-coction and ephedra. The levels of Glu and Asp reached peaks from 90 min to 120 min after treatment with Mahuang decoction,and also increased along with dose increase of Mahuang decoction.In comparison with the medium dose of Mahuang decoction group,the level of Glu reached peak at 90 min and 150 min in ephedra alkaloids group and ephedra group respective-ly,and the content of Glu significantly increased at peaktime.Conclusions Increasedcontentofexcita-tory amino acid neurotransmitters (Asp and Glu ) shows positive correlation with the dose of Mahuang de-coction.Other components in Mahuang decoction in-hibits the up-regulation effect of ephedra and ephedra alkaloids on Glu,and promotes the up-regulation effect of ephedra alkaloids on GABA and Gly.%目的 应用微透析技术,研究中医经典方剂——麻黄汤对大鼠脑海马区4种氨基酸类神经递质(谷氨酸Glu、甘氨酸Gly、天冬氨酸Asp、γ-氨基丁酸GABA)释放的影响,并与麻黄药材、麻黄生物碱的作用相对比.方法 SD大鼠分为6组:麻黄汤高剂量组(以麻黄生药计4 g·kg-1)、中剂量组(以麻黄生药计2 g·kg-1)、低剂量组(以麻黄生药计1 g·kg-1)、麻黄药材组(以麻黄生药计2 g·kg-1)、麻黄生物碱组(麻黄碱7 mg·kg-1、伪麻黄碱2.4 mg·kg-1、甲基麻黄碱1.12 mg·kg-1)以及空白对照组.在动物清醒状态下,微透析采样技术从大鼠脑海马区取样,建立邻苯二甲醛柱前衍生高效液相色谱-电化学法(HPLC-ECD)检测脑透析液中4种神经递质的含量.结果 4种氨基酸类神经递质在28 min内达到良好的分离.麻黄汤各剂量组、麻黄药材组和麻黄生物碱组大鼠脑海马区4种神经递质的含量均增加,与空白对照组比较差异有显著性(P<0.05).与中剂量麻黄汤组比较,麻黄生物碱组在90 min时明显降低了抑制性氨基酸神经递质Gly和GABA水平.大鼠口服麻黄汤各剂量、麻黄药材水煎液后,海马区兴奋性神经递质Asp和Glu水平呈先增后降的趋势,麻黄汤各剂量组大鼠Glu和Asp水平在给药后90~120 min达峰值,随着麻黄汤给药剂量的增加,Asp和Glu含量亦增加.与中剂量麻黄汤组比较,麻黄水煎液组和麻黄生物碱组Glu水平分别在90 min和150 min达峰值,达峰值时Glu含量均明显增加.结论 麻黄汤剂量与Asp、Glu含量的增加呈现一定的正相关性.麻黄汤中其它组分抑制了麻黄和麻黄生物碱升高Glu水平的作用,同时促进了麻黄生物碱对GABA及Gly含量的升高作用.
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