Expeirmental Research On Modiifed2-VO Model Of VD Rat And Effect Of Rosemary Compound Essential Oil On Its Learning And Memory

Objective To explore vascular dementia (VD) rat model caused by chronic cerebralhypoperfusion by using the modified bilateral common carotid arteries ligation andappraise the stability and reliability of the model; to observe the rat’s abilities oflearning and memories and the expression of choline acetyltransferase of hippocampusCA1region by means of rats inhaling and smelling rosemary compound essential oil.Methods1）Adopt the vascular dementia rat model caused by permanent chronicbrain hypoperfusion, by the method of bilateral common carotid arteries ligation. MaleSprague Dawley(SD) rats (N=48), aged2months, were randomly divided intomodified2-VO group(20cases), standard2-VO group(20cases) and sham-operationgroup(8cases). In the standard2-VO group, bilateral common carotid arteries wereligated; in the modified2-VO group, right lateral common carotid arteries were ligated,1week later, left lateral arteries then ligated. Each group’s survival rate was respectivelyrecorded after48hours and60days, and learning, memory and motor abilities weremeasured in the water maze test two months later, after which, the rats were killed toobserve the morphological damage of the hippocampus and striaturn.2) Adopt thevascular dementia rat model caused by permanent chronic brain hypoperfusion, by themethod of modified2-VO.60male SD rats, aged2months, were randomly divided intonormal control group (n=10), and sham-operation group (n=10); the alive rats in themodified2-VO model after48hours were again randomly divided into model group(n=10), rosemary compound essential oil group (n=10) and edaravone group (n=10). The rosemary compound essential oil group was given to inhale and smell the rosemarycompound essential oil made up of3essential oils of rosemary, eugenol and peppermint;the edaravone group was given the injection of edaravone injecta. Both the interventionslasted for65days. Finally, the water maze experiment was taken to testify if abilities oflearning and memory were decreased in rat models and if these abilities in the rosemarycompound essential oil group were improved; the morphological damage of hippocampalCA1region and the change of choline acetyltransferase expression relevant to abilities oflearning and memory were examined under the employment of immunohistochemistry.Results The experiment showed that death rates in modified2-VO group and standard2-VO group after48h and60d declined obviously (P<0.05). Compared withsham-operation group, the learning abilities and memories in the two model groupspresented a distinct difference(P<0.01), while they were rarely different between the twogroups (P>0.05). There was no significant difference in motor function among the threegroups and no distinct pathomorphology change appeared in the hippocampal synapseand striaturn of the two model groups.2) The survival rate in modified2-VO modelwas relatively high, with75%, and the rats’ motor function among the three groups didn’treveal distinct differences (p>0.05). Thirty-day and sixty-day escape latency showed theconspicuou higher of the model group compared with sham-operation group and normalcontrol group (p <0.01); escape latency in the rosemary compound essential oil groupwas obviously lower than that in model group (p <0.01)，but the rosemary compoundessential oil group had no distinct difference with the edaravone group (p <0.01). As tothe times of passing through the platform in the spatial exploration experiment, themodel group exhibited shorter compared with sham-operation group and the normalcontrol group (p <0.01); the time of the rosemary compound essential oil group wasclearly more than that in model group but no different from that of edaravone group (p <0.01). The model group of the hippocampus and the striaturn morphological damageevidently; The number of positive units ChAT activity and the grade of value in hippocampal CA1region in model group were significantly less than that insham-operated and normal control group (p <0.01); the rosemary compound essential oilgroup and the edaravone group have more expression than the model group (p <0.01),while there was no distinct difference between the rosemary compound essential oil groupand edaravone group (p>0.05). Compared with the model group, the rosemarycompound essential oil group and edaravone group can reduce damages of neuronal ofthe hippocampus and increase expression of choline acetyltransterase evidently.Conclusion: Modified2-VO can duplicate VD model caused by permanent chronic brainhypoperfusion, resulting in the damage to neuronal of hippocampal and straturn, but noinjuries in motor function. There is no substantial difference between the modified2-VOand the standard2-VO in establishing the vascular dementia modules, but the former’ssurvival rate rises remarkably.2) Through rats’ inhaling and smelling, the rosemarycompound essential oil can improve the abilities of learning and memory of vasculardementia rats caused by permanent chronic brain hypoperfusion, decline the damage tothe neuronal of the hippocampus and increase the expression of choline acetyltransterasewhich has a therapeutic effect on the vascular dementia.