Study On Blood-brain Pharmacokinetics Characteristics Of Gastrodia Elata Component C Based On Microdialysis Technique

ObjectiveThe research group studied the pharmacodynamics of component C of Gastrodia elata in the early stage,and the results showed that the component C of Gastrodia elata has a good effect on anti-ischemic stroke（Ischemic stroke,Is）,and its structure is relatively stable and safe,so it is expected to become a promising candidate for new drugs against ischemic cerebrovascular disease.In this study,the pharmacokinetic study was further carried out on the basis of the previous study.In the experiment,the blood-brain non-clinical pharmacokinetic parameters of component C of Gastrodia elata were obtained by microdialysis sampling technique.according to the concentration data of component C in vivo and related pharmacokinetic parameters,the effect and mechanism of component C on target organs were further elucidated in order to comprehensively judge its medicinal properties,that is,to provide experimental basis for new drugs against ischemic cerebrovascular disease from the link of cerebral neuroprotection.MethodIn this study,microdialysis combined with HPLC was used to study the blood-brain pharmacokinetics of component C of Gastrodia elata.The research methods are as follows:1.Establishment of a method for the determination of component C of Gastrodia elata in ratsTo establish a method for the determination of component C of Gastrodia elata in blood dialysate,brain dialysate,liver and brain by HPLC.The specificity,linear range,lower limit of quantification,precision,accuracy,stability,matrix effect and extraction recovery were investigated.The results should meet the requirements of quantitative analysis of biological samples.2.Study on Blood-brain Pharmacokinetics of component C of Gastrodia elata in Rats2.1 Investigation on the factors effecting the recovery rate of microdialysis probeIn this experiment,the established method for determining the HPLC content of component C of Gastrodia elata in blood-brain dialysate was used to investigate the factors affecting the recovery rate of microdialysis probe,positive dialysis method and reverse dialysis method were used to study the in vitro and in vivo recovery rate of component C of Gastrodia elata in blood and brain microdialysis probe in rats,the effects of perfusion rate and drug concentration on the probe recovery rate in vivo and in vitro,and the stability of probe recovery in vivo and in vitro.2.2 Study on Blood-brain Pharmacokinetics of component C of Gastrodia elata.Pharmacokinetic study of component C of Gastrodia elata in rats:the blood probe was implanted in the jugular vein of SD male rats,and the brain probe was embedded in the cerebral cortex,and the component C of Gastrodia elata was given to rats with 800mg·kg^-1（ig.）.Microdialysis technique was used for simultaneous in vivo sampling,HPLC was used to detect the drug concentration in the dialysate,and the probe recovery rate was used to correct the drug concentration.The blood-brain pharmacokinetic parameters were obtained by non-compartment model fitting with DAS3.0 software.3.Study on the distribution of component C of Gastrodia elata in rat liver and brain.The content of component C of Gastrodia elata in Tissue homogenate was determined by HPLC.The content of Gastrodia elata component C in liver and brain was determined by Gavage（20 min）,equilibrium phase（30 min）and elimination phase（120 min）.To evaluate its distribution in liver and brain.Result1.Establishment of a method for the determination of component C of Gastrodia elata in ratsThe HPLC analysis method established by the experiment has a good linear relationship within the required range,and the chromatographic specificity,precision,accuracy,matrix effect,extraction recovery and stability all meet the requirements.It can be used to study the pharmacokinetics of component C of Gastrodia elata in rats.2.Study on Blood-brain Pharmacokinetics of component C of Gastrodia elata in Rats2.1 investigation on the factors affecting the recovery rate of microdialysis probe.In this experiment,through the investigation of the influence factors of probe in vivo and in vitro,it was found that in the in vivo and in vitro recovery test,the recovery rate measured by positive dialysis method and reverse dialysis method decreased with the increase of flow rate at constant mass concentration.the in vitro recovery rate was basically the same,and the in vivo recovery rate was lower than the in vitro recovery rate,while at a constant flow rate,the mass concentration of Gastrodia elata component C had no effect on the in vivo and in vitro recovery rate of blood brain probe.Under the condition of constant concentration and constant flow rate,the blood-brain microdialysis probe of Gastrodia elata component C remained relatively stable within 12 hours,and the recovery rates of blood-brain probe were（45.32±2.83）%and（10.55±0.82）%,respectively.2.2 Study on Blood-brain Pharmacokinetics of component C of Gastrodia elata.In this part,the pharmacokinetic characteristics of Gastrodia elata component C were studied by intragastric administration of Gastrodia elata component C.the MRT_0-∞（average residence time）of Gastrodia elata component C in blood and brain tissue were 48.2min and 51.6 min,respectively.AUC_0-∞（drug-time curve area）were4455.568±2208.383μg·mL^-1·min and 2172.165±828.684μg·mL^-1·min,respectively.C_max（peak concentration）was 88.672±42.733μg·mL^-11 and 45.059±19.158μg·mL^-1T_max（time to peak）was 30min and 32min,respectively.t_1/2（half life）was 17min and43 min,respectively,and the cerebral blood distribution ratio（AUC brain/AUC blood）was 48.75%.3.Study on the distribution of component C of Gastrodia elata in rat liver and brain.After intragastric administration of component C of gastrodia elata,component C was distributed in the liver and brain of the rats in the absorption phase,balance phase and elimination phase,and the distribution in the liver was larger than that in the brain.Conclusion.This subject combined with microdialysis technology to study the blood-brain pharmacokinetics of Gastrodia elata C in rats,it was found that Gastrodia elata C can quickly enter the brain tissue from the plasma through the blood-brain barrier,and the distribution in the brain reaches With a plasma dose of 48.75%,the brain retention time is longer than that of plasma,and the elimination half-life in the brain is more than twice that of plasma elimination,indicating that this component is expected to reach the site of action quickly after it enters the bloodstream,and fully interact with the brain tissue.The distribution of the main metabolic organs in the liver and effect target organs in the brain shows that component C is distributed in the liver and brain,and the distribution in the liver is greater than that in the brain.It is clear that Gastrodia component C has brain targeting.