| Huntington disease(HD)is a neurodegenerative disorder caused by the unstable and abnormal expansion of CAG repeats in IT15 gene,and it is characterized by a wave of degeneration in the striatum.However,the cure for this disease remains uncertain yet.3-nitropropionic acid(3-NP),one kind of the inhibitors for succinate dehydrogenase(SDH),plays an important role in oxidative phosphorylation.High dose of 3-NP induces cell loss in striatum;therefore it was ever used for making HD model on animals.Interestingly,several recent studies have reported that low dose of 3-NP would not cause any histopatholotical abnormity;moreover,it could prompt the ischemic tolerance of the neurons and protect dopamine neurons.Based on the fact that 3-NP has been regarded to be able to generate the best effect in protection for chemical preconditioning,here,we established the HD model on rats,and investigated the protection effect of low dose of 3-NP in HD preconditioning;hopefully to provide another point of view for cure HD.Objectives:To establish an excitotoxic model of HD on rats and to observe its effect in rats’ ethological and histopatholotical changes.Furthermore,to look into the neuroprotective effect of low dose of 3-NP preconditioning on the rat HD model in order to provide experimental findings which can be applied for cure HD.Methods:Stereotactic operation of unilateral injection with quinolinic acid(QA)in the right striatum of rats(HD group)was used to induce the excitotoxic HD model.2 weeks after the operation,apomorphine(APO)-induced rotation test,climbing-net test,open-field test(OFT)and Morris water maze(MWM)test were performed respectively to examine the rats’ ethological changes.Moreover,the immunohisto-chemistry(IH)was used to examine rats’ calbindin-positive neurons in the striatum.Additionally,another rats were injected with the 3-NP at intraperitoneal dose of 20mg/kg(3-NP group),and received intrastrital QA injection 24 hours later(3-NP PC group).2 weeks later,ethological tests were again assessed;test of TUNEL was used for examining the neural cell apoptosis in cortex and striatum;IH and Western Blot were for testing the Bcl-2 protein expression and RT-PCR was for bcl-2mRNA expression as well.Results:(1)2 weeks after the operation,HD group demonstrated ipsilateral rotations in the APO-induced rotation test and less climbing,rearing and glooming in the OFT than the control group,indicating that their exploratory activities declined.For the MWM test,HD group spent more time finding the platform,and showed slower swimming velocity and lower memory frequency for the original platform quadrant,which suggested that their spatial learning ability also decreased.Besides,HD group had smaller amount of calbindin-positive cells in the striatum(all Ps<0.05).(2)3-NP group showed no ethological or histopatholotical abnormity.For ethological changes,3-NP PC group showed less times of APO-induced ipsilateral rotations,better exploratory activities in the OFT,significant improvement of spatial learning ability in the MWM test,and demonstrated more calbindin-positive cells in the striatum than the HD group.Menawhile,they showed less TUNEL-positive neural cells and an increase in the expression of Bcl-2 protein and mRNA in cortex and striatum.The above results suggested that low dose of 3-NP preconditioning resulted in the protective effect to the HD model.Conclusions:According to the integration of results,we could conclude that:(1)The QA-induced model of HD on rats resulted in similar ethological and histopathological changes as human HD,which provided the evidence that unilateral injection of QA(240nmol/1μl)in the striatum could be a reliable method to make a rodent excitotoxic model of HD.(2)Low dose of 3-NP preconditioning could inhibit the apoptosis of neural cells to induce neuroprotection on HD,and the mechanism of this protective effect was possibly related to up-regulate the transcription and translation level of Bcl-2. |
PDF Full Text Request