Proteasome Inhibitor Lactacystin Induces Parkinson's Disease In Animal Models

Objective:Parkinson's disease is a progressive neurodegenerative disease.It is characterized by the impairment of motor function including bradykinesia, resting tremor, rigidity, gait abnormalities and postural instability. Pathologically, PD is marked by the selective loss of dopaminergic neurons in the substantia nigra compacta parts and the presence of intracytoplasmic proteinaceous inclusions known as Lewy bodies. Although the molecular mechanism of DA cell death is not fully understood , it is associated with oxidative stress,mitochondrial dysfunction,inflammation and gene mutant.At present,dysfunction of the ubiquitin-proteasome system is one of the factors related to the pathogenesis of PD.Its mechanism is not clear now.We don't know if there are other compositions in lewy body except for [alpha]-synuclein.It is a question how many kinds of protein in lewy body and What roles they take in pathogenesis of PD. It takes many years to identify one kind of protein in an orthodox way.With the appearance of proteomic technique, which is advanced , high-flux and integration,it will turn the study on proteomics of lewy body into reality. Because human brain is especial,we have difficulties to get unsalted samples of patients who have Parkinsons disease. We need induce proper animal models to substitute of human brain.6-OHDA can induce PD animal models successfully ,which can induce dopaminergic neurons lossing ,but there are no inclusions in cytoplasm of dopaminergic neurons.In MPTP inducing animal models,there are no inclusions information in intracytoplasmic of DA neuron.Rotenone can induce rats to take on pathology hallmark of PD,but which have a high mortality.At present,investigators have found that protesome inhitor can induce the presenceof intracytoplasmic proteinaceous inclusions known as Lewy bodies by inhibiting UPS.So it is possible to solve the question of proteomics and it is also singificant to study UPS in pathogenesis of Parkinsons disease.It can provide us an aim to cure parkinsons disese.In our experiment we will make use of lactacystin to induce PD in animal models.Method:Lactacystin (10ug,2ug,0.2ug)and vehicle(0.9% saline) was unilaterally infused above SNc or into SNc by stereotaxic procedure.In order to continuously observe the changes of behavior and pathological characteration in bilateral SNc of the rats after being treated, we had some midbrain sections strained with hematoxylin and eosin,the other sections immunohistochemistry stained with primary antibody to tyrosine hydroxylase and [alpha]-synuclein following behavioral assessments at different time。Result:Those rats directly being injected 10ug lactacystin into SNc took on spontaneous rotation ,which died partially after the abnormal behvior lasting one week.The rats which were treated by 10ug and 2ug lactacystin above SNc took on bradykinesia, transient tremor, rigidity,arch its back ,losing weight and decreasing food.These abnormal action also happened in the rats which were treated by 2ug lactacystin into SNc.The rats which treated by both 0.2ug lactacystin and 0.9% saline were all normal in behavior and dopaminergic neurons.There was no difference in these teams (p > 0.05).There was dopaminergic neurondegredation and lewy bodies information in dopaminergic neurons in the rats which were injected either 2ug or 10ug lacatacystin of two drug injection parts. On the 21th days after the injection,the dopaminergic neurons were lossed in rats which were injected 10ug or 2ug lactacystin(p<0.01).The loss of tyrosine hydroxylase positive neurons was observed in doseand time dependent manner.Inclusion:It takes a lot of time to induce PD model,which is affected by many factors.At present ,proteasome inhibitor can induce PD model by stereotactic technique, hyodermic or intraperitoneal injection.Medicament is injected into unilateral SNc by stereotatic injection in most experiments,which injected into bilateral striatum or SNc in minority experiments. Most experimentalists observe action and pathological changes of PD models from the first week to the third week. In our study ,we injected lactacystin into SNc or above SNc by stereotactic technique .By this way,we have successfully induced PD model which not only took on especial behavior of PD but also shew some especial changes of pathology,such as the loss of dopaminergic neurons and the presence of [alpha]-synuclein position proteinaceous inclusions .So we can conclude that lactacystin can induce models of Parkinsons disease in rats.Some characters of Parkinson disease were found in this kind of models,including the changes of behavior ,dopaminergic neurodegeneration and [alpha]-synuclein aggregation.We found lactacystin which injected into SNc or above SNc can cause dose-dependent and time-dependent destruction of dopaminergic neuron . It can successfully induce PD in rats.Ten microgramme is the best does for inducing PD model and the optimal observation time is from the third to the fifth week.It is say that Ubiquitin-Proteasome pathway plays a important roles in the pathogenesis of Parkinsons disease.Animal models of Parkinsons disease induced by protease inbibitor take a important role in the study of pathogenesis and proteomic.It is another path to find a available way to treat PD in Ubiquitin-proteasome system.This kind of model is pragmatic to have study of proteomics in lewybody.