Empirical Study Of The Mesolimbic Dopamine System Lesion By Stereotaxic Technique

Objective: To study the effect of cognition on the rats who underwent multi-targets ofmesolimbic dopamine system lesion by stereotaxic technique.so to bolting the safetystereotaxic surgery targets.Methods: fifty adult Spraqui-Dawlay rats were divided randomly into three groups:lesion group, normal contral group, sham lesion group. Lesion group includes forty ratswho divided averagely into four groups: lesion nucleus accumbens septi (NAc)group(lesion position: cingulate gyrus +NAc); lesion amygdala group(lesion position:cingulate gyrus+basolatal amygdala); lesion hippcamp(Hip) group(cingulate gyrus+HipCA3); lesion septal area group(cingulate gyrus+ septal area). To lesion syndrnonizedlyand symmetrially different targets of rats by direct current with stereotaxic technique anddetermine the lesioned location and extension by histological technique. After one andtwo week post-operation, to evaluate the effect of operation on the rats' cognition byMorris water maze locating navigation test and space pilot test.Results: After lesioned successfully and exactly the targets of mesolimbic dopaminesystem, the test show: NAc lesion rats who seeking platform at first week post-operationprlong escaping delitescence form 10.1±1.2s to 13.2±1.4s, it have statisticdifference(t=16.24,p＜0.01); at second week ,it was shortened to 9.6±0.9s and less thanpre-operation. Difference is significant: (t=5.31,p＜0.01).Their staying time at platformshortened from 41.5±3.3s to 35.1±2.8s, Difference is significant: (t=4.30,p=0.004).Itrecovered to the normal level at second week post-operation. So cognition of NAc lesionrats with heroin addiction decreased temporally post-operation, then recovery to thenormal or super level. Amygdula lesion group is similar. However Hip lesion groupdiscovered that escaping delitescence extended and exploring time shortened obviously.Both have statistics difference, and haven't significant change at second week post-operation.Septal area lesion group is similar to the Hip group, moreover its levellower.Conclusions: 1.Amygdala lesion don't affect significantly cognition of rats; NAc lesionlead cognition's temporal descent, and it recovers rapidly. Hip or septal area lesion canlead to short/long-term desend (lest two weeks). As for cognition function, it rankaccording to their effect: Hip＞septal area＞NAc, amygdala. 2. Amygdala lesion is safe andeffective target to the stereotaxical lesion surgery. NAc lesion can be the reserved target.As Hip and septal area lesion can influence the rats' cognition significantly, they can't bethe targets of the surgery.