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Objective To investigate the long-term effect of inflammation on behavior,microglias and dopaminergic (DA) neurons in the substantia nigra of intracephalic inflammation rat models induced by intracerebroventricular injection of low-dose(10μg) lipopolysaccharide (LPS).To analyze the relationship between activation of microglias and DA neurons degeneration in order to explore the mechanism of inflammation in the progressive process of Parkinson' s disease (PD).Methods 50 healthy male SD rats were randomly assigned into saline-injected control group and 10μg LPS-injected group.All injections were made intracerebroventricularly on right side of rats with saline or LPS.Moving speed was measured at different time points.At 24 weeks and 40 weeks after saline or LPS injection,specific antibodies of OX-42 and OX-6 were used separately to detect the changes of microglia in the substantia nigra of rat.The changes in morphology and numbers of substantia nigra DA neurons were observed by tyrosine hydroxylase(TH) immunohistochemical staining.The expression and distribution of the degenerated neurons in substantia nigra were detected by using Fluoro-Jade B(FJB).Results ①Analysis of moving speed sho wed that the moving speed of 10μg LPS-injected group rats and saline-injected group rats was similar from 4 weeks to 36 weeks after injection.At 40 weeks post injection,moving speed of 10μg LPS-injected group rats decreased by 24.6％ compared with that of saline-injected group rats (P＞ 0.05 ).②At 24 weeks and 40 weeks after injection,there were many activated OX-42 positive microglias in the substantia nigra of 10μg LPS-injected group rats,but there was almost no significant activated OX-42 positive microglia in saline-injected group.OX-6 positive microglias were not found in the substantia nigra of both of two groups.③At 24 weeks and 40 weeks post injection,the number of TH-positive neurons in the substantia nigra of 10μg LPS-injected group rats decreasedby 24.2％ ( t=4.803,P＜0.01) and 27.6％ ( t=3.212,P＜0.01) respectively compared with those of salineinjected group.④ There was no FJB positive neurons in the substantia nigra of the two group rats.Conclusion Intraventricular injection of low-dose LPS ( l0μg) in rats may induce long-term activation of microglias and chronic degeneration of DA neurons in the subs tantia nigra of rats although the necrosis are not occurs to DA neurons till 40 weeks post LPS injection.Intraventricular injection of low-dose LPS in rats could be ideal model to study the mechanism of chronic degeneration of DA neurons in PD.
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Objective To construct the recombinant rAAV2-hGAD65 vector and detect its function both in vitro and in vivo. Methods The cDNA of human glutamic acid decarboxylase 2 (hGAD65) gene, which was one of gamma-aminobutyric acid (GABA) synthetase, cloned by the method of RT-PCR, was subcloned into the adeno-associated virus (AAV) vector and formed the recombinant vector of AAV-hGAD65 (rAAV2-hGAD65). The recombinant vector was packaged by the AAV Helper-Free System and its titer was detected. The primary fibroblast, cultured from the rat lung, was transfected by the rAAV2-hGAD65. The expression of the hGAD65 in fibroblast was detected by immunohistochemical method and the level of GABA in the media was assayed by high performance liquid chromatograph (HPLC). In vivo, the hGAD65 was detected by immunohistochemical method in STN and the concentration of the GABA in the reticular part of substantia nigra (SNr) was assayed by HPLC after the rAAV2-hGAD65 was injected into the subthalamic nucleus (STN) by the stereotaxic method. Results The sequence of hGAD65 cDNA was in accordance with that in the Genebank. The amino acid sequence of hGAD65 had no mutation and the titer of rAAV2-hGAD65 was reached 4.5 ×10~(11) per milliliter. The efficiency of infection to the rat primary firoblasts was 80%, and the concentration of GABA in the media of fibroblasts was (45.66±6.07)nmol/L per liter. In vivo, hGAD65 could be detected in STN, and the concentrateion of the GABA in the SNr was increased from (5.66±1.07)nmol/g to (12.66±2.59)nmol/g.Conclusion The cDNA of hGAD65 was cloned by RT-PCR and the recombinant vector of rAAV2-hGAD65 was constructed. The AAV can infect the primary fibroblast in vitro and the hGAD65 can catalyse the glutamic acic to GABA. In vivo, the concentration of GABA in the SNr was heighten after the rAAV2-hGAD65 was injected into the STN.
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Objective To investigate whether there is any functional link between p27~(Kip1) function and all-trans retinoic acid (RA) in the control of neuronal differentiation of immortalized human neural progenitor cells (hSN12W-TERT cells). To investigate the mechanism by which p27~(Kip1) regulates the differentiation of immortalized human neural progenitor cells. Methods hSN12W-TERT cells were derived from the striatums of human embryos at 12 weeks gestation and cultured with serum-free medium in presence of EGF and bFGF. At the appropriated time, hSN12W-TERT cells were exposed to 1μmol/L RA for 3, 5, 7 days respectively. The experiment was repeated there times. Cell cycle analysis was performed by flow cytometry analysis (FACS). The expression of p27~(Kip1), p21~(cip1), cyclin-dependent kinase 2 (cdk2), p-cdk2 and S-phase kinase-associated protein 2 (skp2) in hSN12W-TERT cells before and after RA treatment cells were determined by using Western blotting analysis. Results FACS result showed that 77.25% of proliferating hSN12W-TERT cells were in the G1/G0-phase while 9.38% of cells in the S-phase. Following RA treatment, cell growth was arrested, and 85.68% of cells accumulated in G1/G0-phase while 8.57% of cells in the S-phase. Western blotting analysis demonstrated that the levels of p27~(Kip1) in the hSN12W-TERT cells increased following 3 days' treatment with RA compared with those of normal untreated cells, with a peak at 5 days (P<0.05). The similar results were acquired both in nuclear proteins and in cytoplasm proteins of hSN12W-TERT cells. The expression level of p21~(cip1) decreased in response to RA treatment. RA did not affect the expression of cdk2, but the expression of p-cdk2, which represented the activity of cdk2, was markedly decreased in response to RA treatment. Skp2, which was required for the ubiquitin-mediated degradation of p27~(Kip1), was detected in proliferating hSN12W-TERT cells. The expression of skp2 reduced dramatically in response to RA treatment in a time-dependent manner.Conclusion There is a functional link between RA and p27~(Kip1) function in the control of neuronal differentiation in hSN12W-TERT cells. P27~(Kip1) plays a key role during neuronal differentiation. Moreover, high levels of p27~(Kip1) are associated with its degradation inhibiting through reducing proteasome-dependent proteolysis.
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Objective To investigate the role of asctrocytes in the process of chronic degeneration of dopaminergic neurons in intracephalic inflammation rat model induced by intracerebroventricularly injection of lipopolysaccharide.Methods Sixty healthy male SD rats were assigned into lipopolysaccharide group or saline control group randomly.All injections were made intracerebroventricularly on right side of the rats.Ethovison software was used to measure the movement distance of rats within 30 minutes.Specific antibody for glial fibrillary acid protein (GFAP) was used in immunohistochemistry stain to detect the changes of asctrocytes in the substantia nigra of rats.Results Movement distance of lipopolysaccharide-injected rats decreased by 21.2% compared with saline-injected rats at 16 weeks after injection (t=2.54,P<0.05)by 27.0% (t=3.55,P<0.01) at 24 weeks and by 31.4% (t=3.91,P<0.01) at 28 weeks after lipopolysaccharide injection.The asctrocytes were activated obviously in the substantia nigra of lipopolysaccharide-injected group at 2 weeks,while the numbers of GFAP-positively stained cells (228.60 + 22.35) increased significantly compared with saline-injected group ( 165.20 ± 25.97) (t = 4.14,P< 0.05).The activation of asctrocytes was not found in lipopolysaccharide-injected group at 4 weeks and 12 weeks.The asctrocytes were re-activated in the substantia nigra of lipopolysaccharide-injected group at 24 weeks,while the numbers of GFAP-positively stained cells (220.00±21.01 ) increased significantly compared with saline-injected group (169.00± 19.00) (t= 4.03,P<0.05).The activation of asctrocytes was not seen at any time point in saline-injected group.Conclusions Intracephalic inflammation induces chronic degeneration of substantia nigral dopaminergic neurons in rats.The asctrocytes exhibite "acute activation-quiescing-reactivation" state,indicating that they might be involved in the mechanism of dopaminergic neurons degeneration.
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Objective To investigate the effect of Desert Hedgehog on direct differentiation of neural progenitor cells(NPCs) cultured from embryonic mesencephalon in the rats.Methods We infected DHH into COS7,NIH/3T3 and 9L cells,and detected the expression of DHH in the cells with immunofluorescence,real-time PCR and Western blot.All of the three cells were co-cultured with NPCs isolated from ventral mesencephalon in embryonic SD rats(E13.5) respectively.Immunoreactivities of tyrosine hydroxylase(TH) was detected by immunocytochemistry after 10 days.Results The expression of DHH in COS7,NIH/3T3 and 9L cells was remarkably detected,but few TH-positive cells were found in the three co-cultral systems at the 10th day.Conclusion The protein derived from DHH itself does not show any inductive effect on the differentiation of NPCs to the dopaminergic neurons in vitro.
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BACKGROUND: The protein kinase C (PKC) family consists of 3 groups of PKCs, namely the conventional PKC (cPKC), atypical PKC and novel PKC.Accumulating studies conducted in recent years have suggested that PKCs may play important roles in the development of cerebral ischemic/hypoxic preconditioning ( I / HPC ).OBJECTIVE: To observe membrane translocation of hypoxia-activated cPKC isoforms(α, βⅠ, βⅡ and γ) at cellular levels in a cell hypoxia model.DESIGN: Randomized block design.SETTING: Department of Neurobiology, College of Basic Medical Sciences,Capital University of Medical Sciences.MATERIALS: The experiment was completed at the Neurobiological Cell Culture Laboratory of Capital University of Medical Sciences in May 2004.Human neuroblastoma cells with the properties of neurons were maintained and passaged in this laboratory.METHODS: The activation of cPKC isoforms under hypoxic condition and changes of cPKCα, βⅠ, βⅡ and γ membrane translocation(an indicator of PKCs activation) in SH-SY5Y neuroblastoma cells in response to hypoxia (1% 02, 5% CO2 and 94% N2) for 0 to 24 hours were observed using SDS-PAGE, Western blotting and immunocytochemistry.MAIN OUTCOME MEASURES: Effect of sustained hypoxia on cPKC membrane translocation in human neuroblastoma cells was observed with SDS-PAGE, cPKC Western blotting, and immunocytochemistry.RESULTS: cPKCα, βⅠ and βⅡ membrane translocation were increased significantly ( P ＜ 0.05 ) in a time-dependent manner in response to hypoxic exposure, and the increase of cPKCβⅠ was more evident( P ＜ 0. 001 ) after 4hours of hypoxic exposure, whereas no cPKCγ was detected in SH-SY5Y neuroblastoma cells either under normoxic or hypoxic condition. The results suggested that all cPKC isoforms, epically cPKCβⅠ, could be activated by sustained hypoxia, and the absence of cPKCγ in SH-SY5Y neuroblastoma cells may be relevant to the loss of specific biological features of the cultured cells.CONCLUSION: Sustained hypoxia activates the isoforms of cPKCα, βⅠ and βⅡ in human neuroblastoma cells and induces their membrane translocation.cPKCγ isoform may not exist in human neuroblastoma cells, or the cells has lost certain biological characteristics.
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@#ObjectiveTo study the effect the chitosan tube combined with the bio active carrier system on inducing nerve axon regeneration of rats with spinal cord injury.Methods50 female Wister rats were characterized by the right spinal cord hemisections at the seventh and eighth thoracic segment to make the model of spinal cord hemisection. The chitosan tube serving as a regenerative loculus was implanted in the defect location of the experimental models.In the experimental group,the bio active carrier system was injected into the chitosan tube,while in control group injected nothing.The drua was sutured to restore cerebrospinal fluid circulation.Results6 months and 12 months after operation,the regenerative nerve axon had passed the defect area of spinal cord in the experiment group. According to WGA-HRP anterograde axonal tracing study, some TMB-positive axons were observed in the distal graft host interface,and came into the host environment. TEM-ultrastructure indicate some neonate synapse, myelinated nerve fibers.In the control group,few regenerative axon could be seen, there was no regenerative axon pass the middle of the tube.ConclusionsThe chitosan tube in which the bio active carrier system was injected can induce the spinal cord nerve axon regeneration.
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Aim To investigate whether Nurr1 gene,a member of the nuclear receptor superfamily of transcription factors,contributed to 6-OHDA-induced DAergic neurons insults by comparing the effect of 6OHDA on neuroblastoma cells SK-N-SH and SK-N-SH cells overexpressing Nurr1gene(SK-N-SH/Nurr1).Methods The effect of Nurr1 gene on cell proliferation of SK-N-SH cells was investigated,then SK-N-SH and SK-N-SH/Nurr1 cells were exposed to 6-OHDA(5～100 ?mol?L~(-1))for 1～24 h,cells' morphology was observed under phase-contrast microscope.The cells viability was analyzed via MTT assay.Apoptosis was detected using Hoechst33342 staining.Results The Nurr1-overexpressing SK-N-SH cells showed significantly slow growth rate compared with that of SK-N-SH cells.Treatment with 50 ?mol?L~(-1) 6-OHDA changed SK-N-SH-Nurr1 cells' morphology within 1 h,accompanied by retraction of processes,shrinkage of cell body,whereas the morphology of SK-N-SH cells changed after treated with 50?mol?L~(-1) 6-OHDA for 2 h.The result of MTT assay indicated that exposure to 100 ?mol?L~(-1) 6-OHDA for 24 h induced a significant decrease in SK-N-SH/Nurr1 cells survival compared with SK-N-SH cells at various time points with an IC_(50) value of 75 ?mol?L~(-1) and 50 ?mol?L~(-1) respectively in SK-N-SH and SK-N-SH/Nurr1 cells.The evidence that treatment with 75 ?mol?L~(-1) 6-OHDA for 12 h induced typical apoptosis in SK-N-SH/Nurr1 cells was found in morphological features provided by Hoechst33342 staining,including chromatin condensation and nuclear fragmentation,and the percentages of apoptosis in SK-N-SH/Nurr1 cells was about 22%～24%.In contrast,no morphological characteristics of apoptosis in SK-N-SH cells were observed.Conclusions The present study suggests that Nurr1 gene renders SK-N-SH cells more vulnerable to neurotoxic insults. The mechanism of such action is probanly that normal Nurr1 gene function can stimulate apoptotic pathway induced by 6-OHDA,and play a major role in the high sensitivity of DArgic neurons to 6-OHDA insults as a vulnerable factor.
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Aim To study the effect of cyclosporin A and tetrand ri ne on P-glycoprotein (P-gp)of bovine brain capillary endothelial cell. M ethods The fluorescent dye, rhodamine-123 (Rh-123) was used to evaluate t he functional activity of the P-glycoprotein (P-gp) efflux transport system in primary cultured bovine brain capillary endothelial cell (BCEC) monolayer. Results Rhodamine-123 accumulation was increased significantly in monola yer treated with the P-gp modifying agent, cyclosporin A and tetrandrine. Conclusion The observation suggests that this Rh-123 method is sens itive, stable to evaluate the function of P-gp of blood-brain barrier (BBB). R h-123 accumulation is also increased by tetrandrine in dose-dependent manner.
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Objective To determine the ultrastructural localization of MDR1 and GFAP in the surgically resected brain tissues from intractable epilepsy patients. Methods Expression of MDR1 and GFAP in brain tissues was examined by using PAG immunolabeling technique for electron microscopy. Results The MDR1 and GFAP labeled by gold particles were only detected at some reactive astrocytes. The positive gold particles were mainly located in the astrocytic cytoplasm and their membrane, but not in the nucleus.Conclusion The expression of MDR1 and GFAP in the brain of patients with clinically intractable epilepsy were mainly located at the cytoplasm and membrane of certain reactive astrocytics.;
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ObjectiveTo explore the projections of the long descending propriospinal tracts to lumbar enlargement. Method Anterograde tracing with cupric-silver staining. 10 animals were injected b biotinylated dextran in the upper cervical cord. Following survival times of 14 days, projections of the long descending propriospinal tracts were immunohistochemically demonstrated in the lumbar enlargement.Results The degenerated terminals and labeled terminals were found in the bilateral gray matter of the lumbar enlargement, but predominantly ipsilaterally. The terminals were widely distributed in laminal Ⅴ-Ⅸ, heavily Ⅶ and Ⅷ. Conclusion The long descending propriospinal tract from the upper cervical cord projects to the lumbar enlargement.
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We reconstructed and compared 3D digital models of basal ganglia of human and rat. After selecing the sections con-taining basal ganglia from sterotoxic atlases of human and rat, 3D digital model of basal ganglia of human and rat was recon-structed by using general-purpose 3D modeling and animation software 3D Studio MAX and its 3D loft function. Several modifi-cation processes were done then to make the digital model more smooth. The 3D digital models of basal ganglia of human and ratwere successfully constructed and the comparative neuroanatomy study was conducted. The virtual reality technics was then in-troduced into this study, using internet browser, digitalized basal ganglia could be rotated, detached and resembled arbitrarily.Our study showed: (1) No matter on their morohology or their components, there were little differeces.(2) Due to ortho-statism, the rostro-caudal axis of human brain was rotated with certain angle, as the result, the relative positions among nucleiof human basal ganglia did differ from that of rat. (3) The projection fibers arrived the correspoding part of their target nucleiwith the shortest way, which might become the basis of the basal ganglia intrinsic topological projection.
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AIM: To observe the influence of overexpression of ?-synuclein on the cultured SH-SY5Y cells. METHODS: The plasmid of ?-synuclein-pcDNA_3 was transfected into SH-SY5Y cells with LipofectAMINE. The expression of ?-synuclein was determined by anti-?-synuclein immunocytochemistry. The intracellular reactive oxygen species was determined with 2', 7'-dichlorofluorescein diacetate (DCF-DA) by using a FACSCAN flow cytometer and fluorescent microscope. The intracellular content of reduced GSH was detected with glutathione assay kit by spectrophotometer. RESULTS: The ?-synuclein was expressed in cultured SH-SY5Y cells transfected with the plasmid of ?-synuclein-pcDNA_3. The DCF loading analysis and the intracellular level of reduced GSH suggested that the transfected cells were under oxidative stress. CONCLUSION: Overexpression and accumulation of ?-synuclein in SH-SY5Y cells increase intracellular reactive oxygen species levels, it is suggested therefore that the ?-synuclein does play an important role in the pathogenesis of Parkinson's disease.
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The origin of neuropeptide Y(NPY)-like immunoreactive(IR)fibers in the lateral and basolateral amygdaloid nuclei was examined by using indirect immunofluorescence and retrograde tracing method in the rat.1njection of a retrograde tracer.fluorogold(FG),into the lateral and basolateral amygdaloid nuclei,labeled many neurons in the ipsilateral anterior amygdaloid area,and simultaneous treatment with antiserum against NPY stained some of these neurons.Destruction of the anterior amygdaloid area caused an ipsilateral decrease of NPY-IR fibers in the lateral and basolateral amygdaloid nuclei.These findings indicate that NPY-IR neurons in the anterior amygdaloid area project ipsilaterally to the lateral and basolateral amygdaloid nuclei.In addition,the present study also shows that NPY-IR neurons located in the lateral and basolateral amygdaloid nuclei are intrinsic to the amygdaloid complex,since after destruction of the anterior amygdaloid area,some of NPY-IR fibers still can be found in lateral and baso lateral nuclei,and transection of the two major amygdalofugal system,stria terminalis and ventral amygdalofugal pathway,failed to cause the accumulation of NPY-like immunoreactivity in the axons proximal to the section.
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Objective The in situ hybridization method was used with signal amplification system for detecting G-protein expression in taste buds. Methods The gene of gustducin and ?- rod transducin in rat are cloned by RT- PCR. Their sense and antisense probes were labeled with digoxigenin. About 150 taste buds in rat vallate and foliate papillae were analyzed. Results The results showed that there were 1.2 transducin-positive cells and 6.2 gustducin-positive cells counted in each taste bud profile on average. The number of gustduin-positive cells was approximately five times more than transducin-positive cells in taste buds. There were 4. 1% gustducin-positive cells and 0.8% transducin-positive cells in all taste cells. It could not be seen any cross reation of transducin probe to gustducin target. The high expression of transducin in retina was also observed but no gustducin expression could be detected. Conclusion The result of present study proved that both transducin and gustducin were taste G-protein and gustducin was high expressed. Both of them might be involved in taste signal transduction.
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he herpes simplex virus type1 (HSV 1) was used for study on tracing neuronal connections of the cerebellum in the rat. The anterior or posterior lobe of the cerebellum in total 23 rats was injected by HSV 1 (HK 2 strain, from Institute of Virology, Chinese Academy of Preventive Medicine) with the titer of 10 -7 in a volume of 10 15?l for each case. Following a postoperative survival period of 1 5 or 10 days, the animals were perfused and their brains and spinal cords were sectioned and stained immunohistochemically by polycolonal antibodies raised in rabbit against HSV 1. Under the LM, the HSV 1 labelled neurons were shown to be a Golgi like appearance, with clearly labelled cell body and dendrites. It showed that the distributions of the labelled neurons in the CNS depended on the postoperative periods and injection sites. 1. After posterior lobe injection, the labelling was limited in the cerebellum, especially in Purkinje cells and the deep nuclei in 1 day of survival time. Two days later, the labelling could be seen in the vestibular, pontive nuclei and inferior olive nucleus. Anterogradely transneuronal labelling in the ventrolateral thalamic nuclus became apparant 3 days after injetions; 2. After anterior lobe injection, the red nucleus, cuneate nucleus, cuniform nucleus and interstitial nucleus of cajal were labelled after 3 days, in addition to the labelling as shown in those cases with injections in the posterior lobe. The results proved that HSV 1 (HK 2 strain) could be transported both retrogradely and anterogradely in CNS, while the transneuronal transport would mainly occur anterogradely. The distances of HSV 1 transport in neuronal pathways would depend upon the postoperative survival times. This indicates that HSV 1 (HK 2 strain) is a powerful tool for demonstrating the chains of synaptically connected neurons in CNS.
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Following injection of HRP into the cerebellum of the rat, the retrogradely labeled′spinal border cells′ in L_1-L_3 of the spinal cord were examined electron microscopically for understanding the synaptology. Six types of terminal boutons (S, F, Cf, T, G and P types) which terminated on the surface of cell bodies or dendrites of the spinal border cells were recognized. The S- and F-boutons contain spherical and elliptical vesicles respectively. These two types of boutons had relatively broad area contacting with the surface of either cell bodies or dendrites. They could be derided into two sub-types respectively. One was the elonagted giant bouton and the other was the round. Cf-type contain flattened vesicles and it make membraneous′contact′ lacking in specialized pre-and postsynaptic membrane thickenings. T-type contain spherical and large granular vesicles, and dense body was seen beneath the post synaptic membrane. G-type boutons contain large granular vesicles in area of presynaptic. P-type boutons form synapses upon the large S-type boutons and contain pleomorphic vesicles. The postsynaptic membrane of S-, T- and G-types is apparently thicker than the presynaptic membrane and showed to be asymmetrical. Further study is necessary with regard to the sources of different terminal boutons contacting with different portions of the spinal border cells.
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Fourteen adult and immature rabbits were used for the study of laminar scheme of the gray matter in the spinal cord. The spinal sections were cut transversally or sagitally into 80 ?m, 60 ?m, 15?m, and 2?m-thick sections. The sections were stained with toluidine blue or crecyl fast violet for cell body and with Luxol fast blue for myelin sheath. 2?m-thick sections were only stained with pphenylenediamine. In addition, the spinal sections from 2 cases of the animals were treated histochemically for demonstrating AChE activity. According to the Rexed's principle lamination for the cat, we have found that the cytoarchitectonic organization of the rabbit spinal cord was found to be basically similar to that of the cat except for some differences about the extension and structures of the laminae.
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The direct spinal projections from the cerebellar nuclei in the rabbit were retro gradely traced by unilateral injection of WGA-HRP into different levels of the spinal cord, including the cervical, thoracic and lumbar segments. The labeled neurons in the cerebellar nuclei were constantly seen in those animals, in which the upper cervical segments (C_(2-4)) were injected. No labeled neurons could be found in the cerebellar nuclei following injection into the lower cervical cord (C_(6-8)) or more caudal segments. All labeled neurons were located in the caudal parts of the fastigial and the interposed nuclei on the side contralateral to the injection. The results show that there are crossed projections from the cerebellar nuclei directly to the upper cervical cord. This study provide certain morphological evidences for further investigation of some aspects of cerebellar functions on motor coordination.
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Horseradish peroxidase (HRP) was injected unilaterally or bilaterally into the cerebellum of 11 rabbits in order to trace the distribution of labeled neurons in the whole length of the spinal cord. To investigate the ascending side of the axons, hemisections were made unilaterally in the lower thoracic cord of 4 rabbits before injection. The distribution of labeled spinocerebellar tract neurons was rather wide. Neurons in the cervical segments were located in (1) the central cervical nucleus (CCN) in Q_(1-4), (2) the medial part of lamina VI in C_2-T_1, (3) the central part of lamina VII in C_(4-8) and (4) lamina IV-V in C_(5-8). The labeled neurons located in segments caudal to thoracic cord could be divided into two groups. Neurons of the uncrossed tract were located in (1) Clarke's column in T_2-L_4, (2) laminae IV-VI in T_2-L_6. Neurons of the crossed tract were found in (1) the spinal border cells (SBC)in L_(3-6), (2) the medial part of the lamina VII in segments caudal to L_6, (3) lamina V in the sacrococcygeal cord and (4) laminae VII-VIII in the sacrococcygeal cord. The present study suggests that the location and fiber course of the spinocerebellar neurons in the rabbit are quite the same as those in the cat. These results should form a basis for further anatomical and physiological studies of spinocerebellar system in the rabbit.