1、Intrastriatal targets of projection fibers from the central lateral nucleus of the rat thalamusNoritaka lchinohe,Hiroyasu lwatsuki,Kazuhiko ShoumuraNeuroscience Letters 302(2001) 105-108IntroductionThe basal ganglia and the cerebellum are the major subcortical structures that are important for regul
2、ation and control of voluntarymovementProjection from the deep cerebellar nuclei to the motor-related Striatum,which receives inputs from the motor cortical areasHave been reported to be relayed at several thalamic nuclei;the ventral lateral nucleus pars caudails,ventral posterior lateralnucleus par
3、s oralis,area X and central lateral nucleus(CL) in the monkey,and the ventral lateral nucleus and CL in the ratBasal ganglia為大腦半球結構中主要的灰質部分之一，也就是neuron之所在分為：Caudate nucleus （尾狀核） &Putamen (被殼）StriatumCaudate nucleus & putamen 合稱striatum（紋狀體）因經過的axon把他們弄出了條紋的外觀臨床上，basal ganglia是指striatum ,視丘下部神經核,黑質與
4、 運動功能異常有關，特徵，不自主，無目的的運動IntroductionPrecise understanding of the function of these cerebello-thalamo-striatal projections requires detailed knowledge of intrastriatal targets of projection fibers from the cerebello-recipient thalamic nucleiIn the previous studyWe demostrated that thalamostriatal neur
5、ons in the CL receive direct strong projections from the lateral cerebellarnucleus in the rat Special attention toa.whether or not projection fibers from the CL make synapses on dendritic spines,which are a good maker for striatal projection neuronsb.whether or not projection fibers from the CL are
6、in synaptic contact with parvalbumin(PV) immunopostive striatal interneuron,which represent the major class of GABAergic interneurons in the striatumMethoda.Ten male Wistar rats were anesthetized with sodium Pentobarbital (70mg/kg,I.P)b.10% solution of biotin dextran amine(BDA) in 0.01M PB (pH 7.2)
7、was iontophoretically injected in to the CLc.The glass micropipette (tip diameter:15m) using a positive current (5-7 A,7 s on/ 7 s off) for 2030minsSurvivalThe period of 7 days,the rats were re-anesthetized and perfused transcardially with 100ml of saline followed by 500ml of paraformaldehyde and 0.
8、1% glutaraldehyde in 0.1M PB(pH 7.4)Post-fixed in the same fixative and stored overnight at 4in PB,the following day,the brain was serially cut 50 m thick on a microslicerStaining(for dextran)1.wash2.ABC kit(1:1001:200 dilute) for 2h at room temperature3.wash4.0.1% DAB in 0.05M Tris and 0.003%H2O2 B
9、DA-labeled axons were visualized as brownStaining(for PV)PV immunohistochemistry using VIP as a chromogen1.wash2.mouse anti-PV monoclonal antibody diluted 1:1000 for 24h at 4 3.1:200 biotinylated horse anti-mouse IgG antibody 2h4.1:100 ABC kit for 2h5.VIP kitPV immunopositive structures were visuali
10、zed as purpleResultInjection siteTo evaluteThe relative frequency of the CL boutons to all excitatory inputs on PV immunopositive interneurons,we recorded both BDA-labeled and unlabeled boutons which made asymmertical synaptic specializations with PV immunopositive structuresResultBDA-labeled fibers
11、 were distributedmainly in the laterodorsal part ofthe striatum and intermingled withPV immunopositive neuronsAll BDA-labeled fibers were smallin diameter(0.10.3m)and exhibited an extended type ofarborization with long,straight,relatively unbranched trajectoriesthrough neuropilResultOf 408 BDA-label
12、ed terminals,371(90.9%)were in synaptic contract with PV immunonegative dendritic spines , 35(8.6%)made synapses on PV immunonegative dendritic shafts,and only two(0.5%)formed synapses on PV immunopositive dendritic shaftsDiscussionIn the present study,we demostrated that a large proportion(91%) of
13、thalamostriatal fibers from the CL terminated on PV immunonegative dendritic spines,which were assumed to be those of striatal projection neuronsThusThe target preference of thalamostriatal fibers from the CL seems not to have a significant bias to interneurons over projection neurons in the striatu
14、mIn summaryThe cerebello-CL-striatal projection have predominant access(probably excitatory) to striatal projection neurons,and also minor access to PV immunopositive striatal interneurons,which are a strong GABAnergic inhibitory source to striatal projection neuronsGABAGABA神經元的作用是在提供負回饋迴路 (negative feedback loop)目的，增加運動控制系統的穩定性
