The Dose-dependent Effects And Dynamic MEMRI Study In Morphine Withdrawal Stage

This dissertation mainly includes three associated research parts.The first research part is the dynamic MEMRI study in morphine withdrawal stage,the second research part is dose-dependent effects in morphine withdrawal stage and the third research part is the MEMRI study on olfactory inhalation of citral.The first part of this dissertation is the introduction of the backgrouds,it reviews the concerning research backgrouds of this dissertation,which includes the basic principles of MRI and MEMRI,the advantages of MEMRI when compared with fMRI,the introduction of FLASH sequence,the basic concepts of drug addiction and the functional mechanism of drug addiction,the three stages of drug addiction and the neurocircuits of the three stages.The second part of the dissertation is the study of chapter two.Although the brain circuits of withdrawal stage has been widely studied in previous reseaches,less studies involving in the dynamic functional brain activity changes in morphine wihtdrawal stage.In the part,we used the methods of withdrawal behavioral analyses and dynamic MEMRI to reveal the dynamic changes of functional brain activities induced by morphine abstinence,also,different brain regions are activated in different substages of withdrawal.Through these,we have developed a novel MEMRI method to study the functional brain acitivity changes in morphine withdrawal stage and provided an useful reference for future MEMRI reseaches.The third part of the dissertation is the study of chapter three.In this chapter,we investigated the functional brain activity changes respectively in high dose(hmor),low dose(lmor)and saline(sal)group after different doses of morphine were administrated in rats.The withdrawal behavioral analyses,MEMRI and correlation analyses were used to reveal the dose-dependent effects during morphine withdrawal.The results demonstrated that functional brain activity changes are significantly different between hmor and lmor group in morphine withdrawal stage,which were deduced from the comparison between hmor(lmor)and saline group,and the comparison between hmor and lmor group.Hence,the dose-dependent effects during morphine withdrawal also provide an useful reference for basic studies of drug addiction and future curing for addicts.The fourth part of the dissertation is the study of chapter four.In this chapter,we had devised a kind of instrument of olfactory inhalation,to reveal the functional brain activity changes induced by long-term olfactory inhalation of volatile citral,and to evaluate the effectivity of the dose of 40mg/kg MnC12 used in dynamic MEMRI study.We had mainly investigated the voxel-based analyses,ROI-based analyses and correlation analyses of NSI values of ROIs.After citral treatment,the functional brain activities increased in regions of GL and AcbC,also,the functional correlation significantly increased between GL and the associated brain regions.Reasonably,we can deduce that MEMRI could be a promising method in olfactory and brain functional researches and it is effective for the dose of MnCl2 in dynamic MEMRI study.This dissertation firstly developed a novel dynamic MEMRI method to reveal the functional brain activity changes in morphine withdrawal stage in rats,which provided a novel MEMRI model for MEMRI studies.Also,the dose-dependent effects were revealed during morphine withdrawal,which also provided a meaningful supplement for the basic studies of drug addiction.Thirdly,we had investigated the functional brain activity changes through MEMRI induced by inhalation of citral,so that we provided a novel MEMRI manner for long-term olfactory and brain functional researches and provided the effectivity of the dose of MnCl2 used in dynamic MEMRI.