| PrefaceIt is very serious that various kinds of prohibited Orphan drugs were abused except tobacco and alcohol in the present world, which formed a vicious cycle of drug abuse - economy consuming - society harming, especially the dependence of opium drugs. However, therapeutic methods adopted nowadays cant achieve the expected effects to the most people of drug addiction.It is still not clear about the inner mechanism of the body and psychological dependence caused by opium drugs. Especially it is in the initial phase about the research of the psychological dependent mechanism, which is decisive to re-abusers. A lot of studies indicate the mesolimibic dopamine system (MLPS) , the awarding center in the brain, participated in the formation of the psychological dependence of drugs, mainly including the limbic forebrain areas, such as the mesencephalic ventral tegmental area(VTA) where the dopamine (DA) neurons concentrate and the nucleus accumbens ( NAc) and the prefrontal cortex ( PFC) in the main projecting areas. The opium drugs affect the mesencephalic limbic DA system directly or indirectly as well as other dependence drugs, and ultimately alter the DA level in the NAc to mediate the awarding effects. NAc is the central nucleus leading to the awarding effects, which is necessary for producing the psychological dependence.Kanata etc adopted stereosis surgical technology to destroy the anterior part of cingulated gyms of the drug abusers, which relieve their withdrawal symptoms. Seventy - three samples were treated and the healing rate was 83 percent, but it was not accepted commonly because of the major impairment of the cranial opening operation. Our program group utilized the gamma lancet to treat the drug addiction with destroying the anterior part of cingulated gyms of the drug abusers, which got some curative effects. Therefore, Damaging the brain nucle-us that participated in the drug dependence offers a novel pathway for the drug addiction.In the present time, the behavior of drug addiction can be imitated with increasingly precise animal models, and many characters of human drug addiction can be duplicated in the experimental animals. Based in the above theory, this experiment adopted chemically damaging NAc of rats, which were determined by two behavior tests of conditioned place preference ( GPP) and Morris water maze respectively. The effects on CPP of the rats with morphine and the brain function of the rats were evaluated overall, which apply evidence for clinical treatment of drug dependence.MethodsMale wistar rats were selected as experimental samples. Under the guidance of the brain solid positioner, 6 - hydroxydopamine were slowly injected into the bilateral NAcs of all the impaired rat groups with a micropipette, and the unimpaired groups were injected saline, and then the CPP test and Morris water maze test were performed respectively. Experimental devices of CPP are place preference boxes of rats, which are comprised of black and white boxes. The experimental rats were divided into four groups, the simple morphine group, and the impaired group with morphine, the simple impaired group and the control group. The passage between the two boxes was blocked by the closure. Morphine hydrochloride and saline of the same volume were injected into the abdominal cavity of the two groups with morphine twice a day in the continuous six days. The rats with morphine were put into the white box and the rats with saline were put into the black boxes. The other two groups were injected with saline of the same volume, and were put into the two boxes respectively. The dosage of morphine and saline increased gradually. The test started after the closure between the boxes was lifted, and the rats with no substance acted freely. The time of the rats staying in the black and white boxes was recorded in fifteen minutes and the differences among the four groups were measured.The experimental device of Morris water maze was a round sink, whose wallwas marked and divided into four quadrants.
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