| Objective:to observeethological changes and intervention effect of Chinese medicine, by method of soothingliver.clearingheat and invigorating spleen and taking contextual conditioning fear rats as animal model of GAD,and investigate the metabolic changes in bilateral prefrontal cortex and hippocampus by using technology of MRI and MRS,so as to explore the pathological mechanisms of GAD and the drug action mechanism of Chinese medicine from the view of cellular metabolism,by which theory about treating GAD with method of Chinese medicine can beconsummateand theclinical value can be improved.Methods:Male Wistar rats were randomly divided into normal group,model group, control group and therapy group. Rats of normal group received free water and feeding, other groups received contextual conditioning fear stimulus everyday to make models for20days. At the same time of making models,freezing time of rats was observed and recorded,and three groups received intragastic administration ofdistilled water,Buspirone Hydrochloride and Chinese medicine decoction of soothing liver,clearing heat and invigorating spleen respectively once a day for3weeks. On the second day after all stimulations,OFT and EPM test were carried on. Video system recorded the actions of rats during testing, and ethological parameters were gotten by professional software ofbehavioral analysis for judging anxiety level. The parameters included acting distance in total,distance and time in central region,distance and time in peripheral region,quantity of rearing, grooming and defecation in OFT and total entry times in open arms and close arms, respective entry times and time in open arms and close arms, quantity of head-dipping,rearing,grooming and defecation in EPM. After behavioral tests,MRI and MRS scanning were carried on so that weighted images of T1and T2were gotten and concentration of metabolites including NAA.Cho, Cr and Glu in bilateralprefrontal cortex and hippocampus of rats were detected by7.OT1H magnetic resonance spectroscopy. Finally, differences in ethological changes and concentration of metabolites among groups were analyzed and out of contrasting.Results:During the process of making models,rats of three stimulated groups behaved obvious fear regression. About the percentage of freezing time,no difference was showed among model group, control group and therapy group in the interior-group contrasting, also in inter-group contrasting,on days of2/3/7/12/17,there was no difference among model group, control group and therapy group. But on days of4/5/8/9/10/13/14/15/18/19/20, control group was lower than model group (P<0.05,P<0.01).On days of8/9/10/13/14/15/18/19/20, therapy group was lower than model group (P<0.05,P<0.01). On days of2/3/4/7/15/12/17/18/19/20, there was no difference between control group and therapy group. On days of5/8/9/10/13/14 therapy group was higher than control group (P<0.05,P<0.01)Open-field test showed:Comparing to normal group,distance in total,distance and time in central region, distance in peripheral region, quantity of rearing in model group, control group and therapy group decreased signif icantly(P<0.01), time in peripheral region, quantity of grooming and defecation grew (P<0.05,P<0.01).Comparing to model group,distance in total,distance and time in central region,distance in peripheral region, quantity of rearing in control group grew (P<0.05,P<0.01).time in peripheral region,quantity of grooming and defecation decreased (P<0.05,P<0.01);distance in total,distance and time in central region,distance in peripheral region,quantity of rearing in therapy group grew (P<0.05, P<0.01),time in peripheral region,quantity of grooming and defecation decreased signi-ficantly (P<0.01). There was no difference between control group and therapy group in all parameters of OFT.EPM test showed:Comparing to normal group, total entry times, percentage of entry times in open arms, percentage of entry time in open arms,quantity of head-dipping and rearing in model group,control group and therapy group decreased (P<0.05,P<0.01).quantity of grooming and defecation grew (P<0.05,P<0.01).Comparing to model group, total entry times,percentage of entry times in open arms,percentage of entry time in open arms, quantity of head-dipping and rearing in control group grew (P<0.05,P<0.01).quantity of grooming and defecation decreased (P<0.05,);total entry times,percentage of entry times in open arms,percentage of entry time in open arms,quantity of head-dipping and rearing in therapy group grew significantly (P<0.01).quantity of grooming and defecation decreased (P<0.05). There was no difference between control group and therapy group in all parameters of EPM test.MRS analysis showed:Comparing to normal group,NAA/Cr of right prefrontal cortex decreased (P<0.05,P<0.01),Cho/Cr decreased significantly (P<0.01),Glu/Cr grew (P<0.05,P<0.01) in model group,control group and therapy group. Comparing to model group,NAA/Cr of right prefrontal cortex grew significantly (P<0.01),Cho/Cr grew (P<0.05), Glu/Cr decreased (P<0.05) in control group and therapy group. Comparing to normal group,NAA/Cr of right hippocampus decreased significantly (P<0.01),Cho/Cr decreased significantly (P<0.01),Glu/Cr grew significantly (P<0.01) in model group,control group and therapy group.Comparing to model group,NAA/Cr of right hippocampus grew (P<0.05),Cho/Cr grew (P<0.05,P<0.01),Glu/Cr decreased (P<0.05) in control group and therapy group. There was no difference in concentration of metabolites in right prefrontal cortex and right hippocampus between control group and therapy group. There was no difference in concentration of metabolites in left prefrontal cortex and left hippocampus among four groups.Conclusions:As an animal model,contexual conditioning fear rats behaved obvious anxiety, which implies that the model can be recommended as a research carrier for the study of pathogenesis of GAD and research and development of new drugs for GAD.Rats of contexual conditioning fear model showed abnormality of cerebral metabolism in region of right prefrontal cortex and right hippocampus. It is implied that neural leisions and dysfunctions exsisting in these pathological regions,including the imbalance between excitatory amino acids and inhibitory amino acids,might be the pathological mechanisms of GAD.Chinese medicineof soothing liver,clearing heat and invigorating spleen showed significant anti-anxiety effect both in behavioral performance and in cerebral metabolism. The mechanism of drug action may be relevant to adjusting abnormal cerebral metabolism, alleviating or buffering neural leisions and dysfunctions caused by strong emotional stress,and also balancing excitatory amino acids and inhibitory amino acids.
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