The Study On The Role And Mechanism Of MGluR5 In Rats With L-DOPA-induced Dyskinesia

Part? Study of the behavior of metabotropic glutamate receptor 5 antagonist MPEP in rats with L-DOPA-induced dyskinesiaObjective: To establish the Parkinson's disease(PD)and L-DOPA-induced dyskinesia(LID)rat model in 6-OHDA-lesioned rats and investigate their behavioral characteristics of metabotropic glutamate receptor 5(m Glu R5)antagonist MPEP in rats with L-DOPA-induced dyskinesia.Methods: The hemi-parkinsonian rat model was established by stereotaxically injecting 6-OHDA to right medial forebrain bundle.After two weeks,apomorphineinduced rotation test was performed to examine the rat model of PD.Forty successfully PD rats were randomly divided into four groups(n=10): saline group,L-DOPA group,MPEP gooup,MPEP plus L-DOPA group.All rats received intraperitoneal injections of saline or the drugs twice daily and continued for 21 days.At days 2,9,11,18 and 21,behavior changes,including rotational response duration,contralateral forepaw adjusting steps and abnormal involuntary movement(AIM)of all rats were performed.Results: 1.Contralateral forelimb adjusting steps were significantly improved after L-DOPA treatment during the whole treatment(P<0.05),but the increasing extent has a tendency to decrease as time prolong,while saline treatment group showed no significant difference(P>0.05).Co-administration of L-DOPA with MPEP significantly increased the forelimb adjusting steps of parkinsonian rats during 21 days of treatment when compared to L-DOPA alone(P<0.05).MPEP treatment alone increased the forelimb adjusting steps significantly(P<0.05).2.Rats subchronically treated with L-DOPA induced the onset and progressive increase of AIM.Co-administration of L-DOPA with MPEP treatment significantly decreased orolingual,axial and total AIM score at day 21(P<0.05).Moreover,the limb AIM scores on the days of 18 and 21 in MPEP plus L-DOPA group were also diminished as compared to L-DOPA group(P<0.05).3.Rotation motor duration of L-DOPA treatment group was shortened significantly at day 11,18,21,as compared to day 2(P<0.05).Co-administration of L-DOPA with MPEP ameliorated the shortening of the rotational motor response duration induced by L-DOPA administration during the period of the treatment(P<0.05).Lesioned rats that received saline an MPEP did not develop AIM and rotational motor at all.Conclusion: 1.MPEP improves motor function in a hemi-parkinson rat model.2.Co-administration of L-DOPA with MPEP ameliorated the shortening of the rotational motor response duration induced by L-DOPA administration.3.MPEP potentiates the antiparkinsonian effects with L-DOPA and partly attenuates LID.Part? Study of metabotropic glutamate receptor 5 and antagonist MPEP,on the effects of synaptic ultrastructure and the postsynaptic density-95 expression in rats with L-DOPA-induced dyskinesiaObjective: To study the effects of m Glu R5 an antagonist MPEP on the striatum synaptic ultrastructural changes and postsynaptic density-95(PSD-95)protein expression in rats with LID.Methods: Forty successfully PD rats continually received injection of saline,L-DOPA,MPEP,MPEP plus L-DOPA respectively for 21 days.After sacrifice,the corticostriatal synaptic ultrastructure were examined and photographed using transmission electron microscope.Striatum was also extracted and western blot was used for the detection of PSD-95.Results: 1.Electron microscopy technique results showed that the postsynapse density depth was much thicker,synapse cleft width was narrower and the ratio of perforated synapses significantly increased in the L-DOPA-treated rats(P<0.05),But MPEP plus L-DOPA treatment could alleviated these changes(P<0.05).2.Western blot showed that L-DOPA treatment increased the protein expression of PSD-95 in the lesioned striatum(P<0.05),while co-treated with MPEP could reversed these changes(P<0.05).Conclusion: 1.Abnormal synaptic plasticity in the corticostriatal pathway is closely associated with the development of LID.2.MPEP attenuated the overactivity of the corticostriatal synaptic ultrastructure induced by L-DOPA treatment and this effect is associated with the abnormal changes of PSD-95.Part ? Study on the role of m Glu R5-mediated Ca MKII-CREB-BDNF signaling pathway in rats with L-DOPA-induced dyskinesiaObjective: To study the role and mechanism of m Glu R5-mediated Ca MKII-CREBBDNF signaling pathway in synaptic plasticity in rats with LID.Methods: Fifty successfully PD rats continually received injection of saline,L-DOPA,L-DOPA+KN-93?L-DOPA+anti-CREB?L-DOPA+anti-BDNF respectively for 23 days.At days 21 and 23,abnormal involuntary movement(AIM)of all rats were performed.After sacrifice,the striatum was extracted and western blot was used for the detection of m Glu R5?P-Ca MKII/Ca MKII?P-CREB/CREB?BDNF.Results: 1.Western blot analysis showed that subchronic treated with L-DOPA elevated the striatal m Glu R5?Ca MKII?CREB?BDNF expression in the lesioned side,MPEP attenuated the overactivity of the m Glu R5?Ca MKII?CREB?BDNF expression induced by L-DOPA administration.2.Ca MKII inhibitor partly attenuates LID,and downregulated the striatal CREB and BDNF protein expression of the lesioned side.CREB inhibitor partly attenuates LID,and downregulated the striatal BDNF protein expression of the lesioned side.BDNF inhibitor partly attenuates LID,downregulated the striatal BDNF protein expression of the lesioned side,while m Glu R5,Ca MKII and CREB protein without inhibition.Conclusion: 1.Ca MKII-CREB-BDNF signaling pathway affect striatal synaptic plasticity in LID.2.m Glu R5 through Ca MKII-CREB-BDNF signaling pathway affect striatal synaptic plasticity in LID.