Experimental Studies Of Brain-derived Neurotrophic Factor Treatment On L-DOPA-induced Dyskinesia Rats With Parkinson’s Disease

Part I Study of brain-derived neurotrophic factor on the behavior of L-DOPA-induced dyskinesia rats with Parkinson’s diseaseObjective: To establish the rat model of Parkinson’s disease(PD) and levodopa-induced dyskinesia(LID) and investigate the effect of brain-derived neurotrophic factor on the behavior of LID rats.Methods: Hemi-parkinsonian rat models were established by stereotaxically injecfion of 6-hydroxy dopamine(6-OHDA) in the right medial forebrain bundle with 60 SD rats. The Parkinson’s disease model rats were randomly divided into two groups: normal saline group, L-DOPA group. All rats received intraperitoneal injections twice daily and continued for 21 days.Each group was further divided into two sub-groups: either intrastriatal microinjection with BDNF(1μg/4μl) or NS(4μl) on the 22 day. Therefore, four groups were finally divided:(1) saline group: injection with NS and intrastriatal injection with NS on the 22 day;(2) L-DOPA group: injection with L-DOPA and benserazide and intrastriatal injection with NS on the 22 day;(3) L-DOPA+BDNF group: injection with L-DOPA and benserazide and intrastriatal injection with BDNF on the 22 day;(4) BDNF group: injection with NS and intrastriatal injection with BDNF on the 22 day. L-DOPA and benserazide were administrated for 7 days after intrastriatal microinjection. At the 2,11,21,23,25 and 29 days,behavior changes of all rats were detected. Comparing abnormal involuntary movement scores of L-DOPA group and L-DOPA + BDNF group, and left forelimb function of 4 groups rats were compared before and after treatment.Results :1.Axial and orolingual abnormal involuntary movement scores were significantly decreased in rats of L-DOPA+BDNF treatment group as compared with those in L-DOPAtreatment group on days 23,25 and 29(P<0.01).The limb abnormal involuntary movement scores of L-DOPA+BDNF group were reduced contrast with L-DOPA group on the 23 and 25 days(P<0.01). 2. Not only L-DOPA group but also L-DOPA + BDNF group, forepaw adjusting steps were significantly increased after with drugs therapy at the behavioral testing(P<0.01). But the forepaw adjusting steps between L-DOPA and L-DOPA+BDNF have no change. 3. All the rats treated with L-DOPA developed a time-dependent reduction in L-DOPA induced rotational response duration(P<0.05). After injecting BDNF to the striatum,the rotational response duration induced by L-DOPA were on decline.There have no otherness between L-DOPA group rats and L-DOPA+BDNF rats.Conclusions: Exogenous administration of BDNF can alleviate abnormal involtmtary movements induced by L-DOPA without disturbing the efficacy of L-DOPA.Part II Effect of brain-derived neurotrophic factor on Trk B proteins expression in striatum of L-DOPA-induced dyskinesia rats with Parkinson’s diseaseObjective: Evaluation the activaty of tyrosine kinase receptor and transcription factor CREB in rats striatum with LID after injected BDNF to striatum,while observing the influence of striatal BDNF injection to endogenous BDNF.Methods: Hemi-parkinsonian rat models were established by stereotaxically injecfion of 6-hydroxy dopamine(6-OHDA) in the right medial forebrain bundle. The Parkinson’s disease model rats were sequentially received intraperitoneal injection of L-DOPA therapy and striatal injection of BDNF. Therefore, four groups were finally divided: saline rats,L-DOPA rats,L-DOPA+BDNF rats,BDNF rats. L-DOPA and benserazide were administrated for 7 days after intrastriatal microinjection. The all the rats were sacrificed after the last injection. Striatum were also extracted and western blot was used for the detection of p Trk B/Trk B and p CREB/CREB, real-time PCR was used to detecte BDNF m RNA level.Results:1. Western blot analysis revealed that BDNF dramatically increased p-Trk B in thelesioned side of the striatum as compared to the matched group. Compared with L-DOPA rats, the level of p Trk B protein expression was increased in rats with L-DOPA+BDNF(P<0.05). Contrast with saline group rats, the p-Trk B protein of BDNF group rats also expressing increased(P <0.05). 2. Western blot also showed that BDNF dramatically increased p-CREB in the lesioned side of the striatum as compared to the matched group. Compared with L-DOPA and salinel rats, the level of p-CREB protein expression was increased in L-DOPA+BDNF group and BDNF group rats(P<0.05). 3. Compared with saline group, BDNF m RNA expression levels of L-DOPA group was increased(P <0.05). Injecting BDNF to striatum increased endogenous BDNF expression, contrasted with L-DOPA and saline group, the BDNF m RNA levels of L-DOPA + BDNF and BDNF group were significantly increased(P <0.05).Conclusions: Striatal injection of BDNF activated BDNF / TrkB signaling pathway, and then promoted the level of transcription of endogenous BDNF.