Effect and mechanism of baicaIin and geniposide on excitotoxicity of acute cerebral ischemia / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE Based on the methods of microdialysis,HPLC-MS/MS and gene chip tech-nology,the mechanism of Baicalin and Geniposide(BC/GP)against excitatory amino acid toxicity in ce-rebral ischemia was studied. This will provide guidance for the clinical application of BC/GP and the study of excitatory amino acid toxicity in cerebral ischemia.METHODS (1)Microdialysis technique and HPLC-MS/MS was performed to study the pharmacodynamics of BC/GP against cerebral ischemia. ①18 SD rats with body weight of(280±20)g were randomly divided into control group,treatment groups with BC/CP at low dose,medium dose and high dose(equal to the dosage of crude drugs for 30 mg·kg-1, 45 mg·kg-1and 60 mg·kg-1respectively).Rats in each group were given intragastric administration for seven days to establish cerebral ischemia model. Then, microdialysis probe was applied to collect cerebrospinal fluid from hippocampus before and after cerebral ischemia. ② First, we established the HPLC-MS/MS method for measuring drugs and excitatory amino acids.Then we detected the microdi-alysis samples and observed their changes in animals.(2)The mechanism of BC/GP against excitatory toxicity of cerebral ischemia were observed at gene level by chip technique. ① 16 SD rats with body weight of 240±20 g were randomly divided into sham group, model group, treatment group of BC(60 mg·kg-1),treatment group of GP(60 mg·kg-1)and treatment group of BC/GP(73)(60 mg·kg-1).Rats in eachgroup were given intragastric administration for seven days to establish cerebral ischemia model. Then the rats were sacrificed,and the hippocampus were rapidly harvested and stored at-80℃for further detection. ②After the quality inspection of the hippocampal,the qualified samples were subjected to detect the levels of neurotransmitter receptor gene in the ischemic of rats by gene chip technology.Finally,the results were analyzed by the method of &Delta; &Delta;Ct.RESULTS (1)Only three compounds includ-ed GP,glutamic acid and aspartic acid were detected in microdialysis samples by HPLC-MS/MS.The concentration of GP increased and lasted for 120 min with a significant dose-dependent after cerebral ischemia.Compared with low dose group,the AUC(0-t),MRT(0-∞),Cmaxand t1/2zin high-dose group showed significant difference(P<0.01).Compared with the model group,the levels of glutamic acid and aspartic acid in the treatment groups decreased significantly,especially in the middle and high dose groups.(2) 89 genes in the neurotransmitter receptor gene signaling pathway were detected by gene chip technol-ogy. There were 22 genes with |Fold Regulation|>1.5 in the model group, compared with the sham group.Five of the 22 genes showed statistically significant differences,including Grin2c(2.9026),Chrna7 (-1.5877), and Tacr2 (-1.7695). Htr3a (-1.8172) and Grm6 (-2.3527). There were 5 genes with |Fold Regulation|>1.5 in the BC group, compared with the model group, Two of them exhibited statistically significant differences,including Brs3(1.797)and Grin2c(-1.7979).There were 14 genes with|Fold Reg-ulation|>1.5 in the GP group, compared with the model group. Three of them displayed statistically significant differences,including Hcrtr2 (-1.6584), Sctr (-3.8524) and Grin2c (-4.8408). Compared with model group, the genes of |Fold Regulation|>1.5 in BC/GP (73) group are 5, and only one of them showed a significant differences. CONCLUSION (1)After administration of BC and GP,GP can cross the blood-brain barrier and reduce the release of excitatory amino acids in the hippocampus. (2) BC/GP can inhibit the interaction between excitatory amino acids and excitatory amino acid receptors and attenuate the toxicity of excitatory amino acids by down-regulating the expression of glutamic acid receptor Grin2c gene.(3)BC/GP may exert their brain protection effect by reducing the release of excit-atory amino acids and inhibiting the expression of excitatory amino acid receptors.