大鼠胚胎中脑神经前体细胞培养、移植治疗大鼠PD模型

目的:研究原代培养的大鼠胚胎中脑前体细胞(mesencephalicprogenitorcells ,MPC)作为帕金森病(Parkinson’sdisease ,PD)细胞替代疗法供体的可行性。方法:PD模型大鼠19只,随机分为细胞移植组(n =9)、假移植组(n =5 )和对照组(n =5 ) ;定期测定移植前后各模型鼠阿扑吗啡诱导的旋转行为的变化,免疫组化定性供体细胞在宿主体内存活和分化的情况。结果:术后6和16周,细胞移植组阿扑吗啡诱导旋转的相对频率与术前比较有显著差异;细胞移植组术后16周时的阿扑吗啡诱导旋转的相对频率平均值与对照组对应的相对频率平均值相比也有显著差异;供体细胞能在宿主体内分化为多突起的DA能神经元。结论:原代培养的胚胎MPC可能作为PD患者细胞替代治疗的供体细胞。     

转基因星形胶质细胞脑内移植治疗帕金森病大鼠的研究

目的　评价酪氨酸羟化酶 (TH)基因转染的星形胶质细胞移植入帕金森病 (PD)模型大鼠脑内后对旋转行为改善作用。方法　用pcDNA3 1/TH质粒转染原代培养的星形胶质细胞 ,采用免疫组化及RT PCR方法检测到TH表达后 ,将转基因的星形胶质细胞移植入PD模型大鼠脑纹状体内 ,观察PD大鼠的旋转行为变化情况。结果　移植后共观察 12周 ,转基因细胞移植组PD大鼠 (n =10 )的旋转行为明显改善 (P <0 0 5 ) ,改善情况在 2～ 8周最显著 ,对照组大鼠 (n =10 )的旋转行为无变化。结论　转基因的星形胶质细胞脑内移植后可短期改善PD大鼠的旋转行为 ,星形胶质细胞有可能作为有效的载体细胞。     

微囊化PC12细胞脑内移植治疗帕金森病的实验研究

目的观察微囊化PC12细胞脑内移植对帕金森病(PD)大鼠模型的治疗作用。方法以6-OHDA分两点注入大鼠纹状体制备PD模型。应用国产新型材料壳聚糖制成的海藻酸钠一壳聚糖一海藻酸钠(ACA)微囊包裹PC12细胞，分别将微囊化PC12细胞、裸PC12细胞、空微囊移植入PD模型鼠损伤侧纹状体内，以阿朴吗啡检测移植前后大鼠旋转行为的差异。行纹状体和黑质的HE染色和酪氨酸羟化酶免疫组化染色观察其病理形态学的变化。对移植的微囊化PC12细胞回收后再培养，以MTT和台盼兰检测细胞活性。结果微囊化PC12细胞移植能够改善PD模型鼠的旋转行为，与移植前和空微囊移植组相比有显著差异(P＞O．05)，症状改善至少持续3个月。裸PC12细胞移植组大鼠的旋转行为也有改善，与移植前相比有统计学差异(P＜O．05)，但仅持续了2个月，移植8周后又渐回到移植前水平，且部分大鼠颅内有致死性肿瘤形成。空微囊移植组移植前后大鼠的旋转行为无明显差异(P＞O．05)。回收微胶囊内的PC12细胞再培养生长良好，MTT法和台盼兰法检测显示细胞具有生物活性。结论微囊化PC12细胞脑内移植能够改善阿朴吗啡诱发的PD模型鼠的旋转症状，ACA新型微包囊能够起到有效的免疫隔离和抑制肿瘤形成的作用。     

同种异体胚脑移植免疫排斥反应实验研究

目的观察同种异体胚脑组织脑内移植是否存在免疫排斥反应以及免疫抑制剂治疗对移植物存活的影响。方法将孕14.5d胚鼠腹侧中脑(VM)细胞悬液移植到帕金森病(PD)模型大鼠纹状体内,术后部分动物每天给予甲基强的松龙(MP)腹腔注射(30mg/kg),分别存活10d、21d、35d和60d,经旋转行为测试后分批处死,行CD4、CD8、主要组织相容性复合体Ⅱ类分子(MHC-Ⅱ)和酪氨酸羟化酶(TH)免疫组化染色。结果移植组10d、21d时,CD4 、CD8 和MHC-Ⅱ 细胞的数量较对照组明显增多,21d时更为显著,35d时部分移植区出现排斥反应,60d时移植区未见移植组织存活。MP治疗组在10d、21d时,移植区CD4 、CD8 和MHC-Ⅱ 细胞数量较未治疗组明显减少,35d时未见明显排斥反应;60d时,CD4 、CD8 和MHC-Ⅱ 细胞的数量较35d显著增加,部分移植物被排斥。MP治疗组各时间点TH 细胞数量明显多于非治疗组,但大鼠的旋转行为在各时间点均未见改善。假手术组在10d、21d时,见少量CD4 、CD8 和MHC-Ⅱ 细胞,35d时消失,各时间点都未见TH 神经元。结论同种异体胚脑组织脑内移植存在免疫排斥反应。MP治疗在一定程度上可以减弱或延缓免疫排斥反应的发生。     

胚胎多巴胺神经元移植治疗帕金森病的实验研究

目的探讨胚胎多巴胺神经元移植对帕金森病大鼠的治疗作用。方法立体定向注射6-羟多巴胺建立帕金森病大鼠模型,随机分为对照组(n=12)和细胞移植组(n=12)。细胞移植组将荧光染料CM-DiI标记的大鼠胚胎多巴胺神经元立体定向注入帕金森病大鼠纹状体区,对照组于相同部位注入生理盐水。用阿扑吗啡诱导帕金森病大鼠旋转行为评估细胞移植的治疗作用。细胞移植8周后取大脑标本行冷冻切片,荧光显微镜下观察移植细胞在脑内存活情况。结果与对照组比较,移植多巴胺神经元能显著改善阿扑吗啡诱导帕金森病大鼠的异常旋转行为(P0.01)。移植8周后,仅少量多巴胺神经元存活。结论多巴胺神经元移植可短期内改善帕金森病大鼠的运动障碍,但长期疗效不佳,可能与移植多巴胺神经元长期存活率较低有关。     

颈上交感神经节脑内移植治疗帕金森病的实验研究

目的研究治疗帕金森病的理想脑内移植物.方法建立SD大鼠帕金森病动物模型,选取SD模型大鼠30只分成3组(移植组12只,对照组12只,空白组6只)用同种成年大鼠颈上交感神经节(SCG)制成细胞悬液,用微量注射器、立体定向仪将细胞悬液植入移植组模型鼠毁损侧尾核头部.每2周观察动物旋转行为变化.6个月后处死动物,制成脑切片,行TH免疫组化及HE染色,切片光镜观察.结果SCG移植后6个月,移植组大鼠旋转行为明显减少.组织学观察发现移植区有TH样阳性细胞存活,且存活数与治疗效果成正比.结论同种异体成年大鼠的SCG脑内移植,移植物能存活并对帕金森病模型鼠有短期治疗作用.     

微囊化PC12细胞移植后帕金森病大鼠旋转行为变化研究

目的观察微囊化PC12细胞移植后帕金森病大鼠旋转行为的变化。方法采用免疫隔离微囊技术将能分泌多巴胺的PC12细胞包裹后,移植到帕金森病大鼠脑内,观察阿扑吗啡诱发病鼠旋转行为的变化,酪氨酸羟化酶(TH)抗体免疫组化染色观察移植区阳性细胞的表达。结果帕金森病大鼠旋转行为有明显改善,由移植前(11.88±2.04)圈/min减少为移植后(3.46±1.01)圈/min。移植后3个月,大鼠脑内微囊完整,仍有TH阳性PC12细胞存活。结论微囊化PC12细胞移植可明显改善帕金森病大鼠的旋转行为。     

SPIO、EGFP双标GDNF基因修饰中脑神经干细胞移植治疗帕金森病

目的探讨超顺磁氧化铁(SPIO)、增强型绿色荧光蛋白(EGFP)双标胶质细胞源性神经营养因子(GDNF)基因修饰中脑神经干细胞(mNSCs)移植对帕金森病(PD)大鼠的治疗作用。方法将PD大鼠随机分为对照组、GFP基因修饰mNSCs移植组和GDNF基因修饰mNSCs移植组,将相应细胞移植到PD大鼠纹状体。阿朴吗啡(APO)诱导PD大鼠旋转行为评估细胞移植的治疗作用。磁共振成像、免疫荧光组织化学研究移植细胞的存活、迁移和分化。结果GDNF基因修饰mNSCs移植能显著改善APO诱导PD大鼠的异常旋转行为;大多数移植细胞停留于移植原位,移植8w后,GDNF基因修饰mNSCs移植组有更多的细胞存活并分化为多巴胺神经元。结论MR I成像可对体内移植的SPIO标记细胞进行活体示踪。GDNF基因修饰胚胎mNSCs移植可显著改善PD大鼠的运动障碍,其分子机制有待进一步研究。     

人羊膜上皮细胞侧脑室移植对帕金森病大鼠模型行为、多巴胺能神经元、神经递质影响的实验研究

目的 观察人羊膜上皮细胞(HAECs)移植入帕金森病(PD)大鼠模型侧脑室后的存活及分化情况,及其对PD大鼠模型旋转行为、纹状体区多巴胺及其代谢产物的影响.方法 采用6-羟多巴立体定向脑内注射制作PD大鼠模型,将制模成功大鼠随机分成3组:人羊膜上皮细胞移植组(HAECs组)、磷酸缓冲组(PBS组)和帕金森组(PD组),1w后腹腔注射阿朴吗啡观察各组大鼠旋转行为的变化,连续观察10w,HAECs组5w后用人特异性抗体Nestin和Vimentin检测人羊膜细胞的存活情况,10w后酪氨酸羟化酶(TH)染色观察各组PD大鼠模型黑质部TH阳性神经元的变化情况及HAECs的分化情况,高效液相色谱--电化学仪测定纹状体多巴胺(DA)、高香草酸(HVA)、3,4-二羟基苯乙酸(DOPAC)等神经递质的水平.结果 HAECs在PD大鼠侧脑室内移植可以长期存活达10w,并且可以分化为DA能神经元,HAECs组大鼠旋转数较PBS组及PD组明显降低(P<0.01),黑质部TH阳性神经元数量较PD组及PBS组升高(P<0.01),HAECs组大鼠纹状体区DA及其代谢产物DOPAC、HVA含量较PBS组明显升高(P<0.05).结论 人羊膜上皮细胞移植入PD大鼠侧脑室可以改善PD大鼠的旋转行为,其机制可能与增加纹状体区DA等神经递质有关.     

人羊膜上皮细胞移植治疗帕金森病鼠的研究

目的 观察人羊膜上皮细胞在帕金森病鼠移植后的存活情况,以及它对帕金森病鼠旋转行为的改善作用.方法 采用6-羟多巴胺立体定向纹状体注射制作帕金森病鼠模型;51只大鼠随机分三组:人羊膜上皮细胞移植组、假手术PBS对照组以及空白模型对照组.制模成功后第5周用人特异性抗体Nestin和Vimentin检测人羊膜细胞的存活情况,第10周切片观察黑质部TH阳性神经元的变化情况,高效液相色谱--电化学仪测定纹状体多巴胺(DA),高香草酸(HVA),3,4-二羟基苯乙酸(DOPAC)等浓度以及脑脊液DA的含量.结果 人羊膜上皮细胞帕金森病鼠侧脑室内移植可以存活达10周;移植组大鼠旋转数较对照组明显降低(P≤0.01);黑质部TH阳性神经元数量较对照组升高(P≤0.01),纹状体区DA、HVA和DOPAC含量较PBS对照组明显升高(P＜0.01～0.05),移植组脑脊液DA含量较PBS对照组也显著增加(P＜0.01).结论 人羊膜上皮细胞侧脑室移植可以改善帕金森病鼠的旋转行为,其机制可能与其增加纹状体区多巴胺等递质水平有关.     

Co-grafted embryonic striatum increases the survival of grafted embryonic dopamine neurons

To enhance the current therapeutic benefit of dopamine (DA) neuron grafts in Parkinson's disease, strategies must be developed that increase both DA neuron survival and fiber outgrowth into the denervated striatum. Previous work in our laboratory has demonstrated that dopaminergic neurons grow to greater size when co-grafted with striatal cell suspensions and display extensive tyrosine hydroxylase-positive (TH+) projections, but no conclusion could be reached concerning enhancement of survival of grafted DA neurons. The aim of the present study was to characterize further the potential trophic effects of striatal co-grafts on grafted mesencephalic DA neuron survival. Unilaterally lesioned male Fischer 344 rats were grafted with either a suspension of mesencephalic cells or with both mesencephalic and striatal cell suspensions. Co-grafts were either mixed together or placed separately into the striatum. Lesioned rats receiving no graft served as controls. Rotational behavior was assessed following amphetamine challenge at 2 weeks prior to grafting and at 4 and 8 weeks following grafting. Only rats receiving co-grafts of nigral and striatal suspensions separated by a distance of 1 mm showed significant behavioral recovery from baseline rotational asymmetry. Both mixed and separate striatal co-grafts were associated with a doubling of DA neuron survival compared with solo mesencephalic grafts. In the mixed co-graft experiment, DA neurite branching appeared enhanced and TH-rich patches were observed, whereas with co-grafts that were separated, TH+ innervation of the intervening host striatum was increased significantly. These results provide the first evidence suggesting that nigral-striatal co-grafts, particularly those placed separately and in proximity to each other, increase both DA neuron survival and neurite extension from the mesencephalic component of the grafts. J. Comp. Neurol. 399:530–540, 1998. © 1998 Wiley-Liss, Inc.     

Embryonic mesencephalic and striatal co-grafts: development of grafted dopamine neurons and functional recovery

Previous neural grafting studies have shown that embryonic dopamine neurons survive transplantation into the parenchyma of the brain; however, fiber outgrowth from those cells is often limited to the immediate vicinity of the graft. More extensive outgrowth is desirable for promoting and maintaining functional recovery of damaged neural systems in animal models as well as human neurodegenerative disorders. The present study examined the possibility of stimulating fiber outgrowth of grafted neurons by simultaneously grafting dopamine neurons with their embryonic target cells. Subsequent functional recovery was evaluated in concert with morphological characteristics of these grafts. Co-grafts of embryonic mesencephalic and striatal cells were implanted into the DA-denervated striatum of rats previously given unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway. Two types of co-grafts were implanted into the DA-denervated striatum: mixed or separate cell suspensions. Tyrosine hydroxylase immunocytochemical analysis of brain sections containing co-grafts revealed extensive arborization of TH-positive neurons in both types of co-grafts. When mesencephalic and striatal nerve cells were implanted into separate sites, TH-positive neurons extended projections that appeared to preferentially reach regions occupied by embryonic striatal neurons. Moreover, the average size of TH-positive cell bodies found in mixed or separate co-grafts was significantly larger than the size of those found in single mesencephalic grafts. Amphetamine-induced rotational behavior was used to assess the degree of functional recovery. In the majority of co-grafted animals, rotational behavior was attenuated by 3 weeks and reversed (amphetamine-induced contralateral rotation) by 5 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)     

Embryonic substantia nigra grafts innervate embryonic striatal co-grafts in preference to mature host striatum

Embryonic substantia nigra grafts partially reinnervate the dopamine-denervated corpus striatum when implanted adjacent to that structure. This reinnervation is generally limited to a small portion of the denervated striatum and does not completely compensate for the behavioral effects of a 6-hydroxydopamine lesion of the substantia nigra. This limited reinnervation may be due to the fact that adult denervated striatum is not an ideal target for dopaminergic neurites. To test this hypothesis, embryonic striatum and embryonic substantia nigra were implanted together into the lateral ventricle of adult rats, adjacent to the denervated striatum. Five months after transplantation, fluorescence histochemistry showed that the embryonic striatal grafts were exclusively reinnervated with little or no reinnervation of the adult host striatum. When substantia nigra was implanted without embryonic striatal co-grafts, reinnervation of the host striatum was observed. We conclude that embryonic striatum is a better target tissue than adult denervated striatum for developing dopaminergic neurites and hypothesize that this difference may be due to the presence or the absence of specific trophic factors.     

Fetal intra-nigral ventral mesencephalon and kidney tissue bridge transplantation restores the nigrostriatal dopamine pathway in hemi-parkinsonian rats

We have previously demonstrated that intranigral transplantation of fetal ventral mesencephalic (VM) tissue and nigrostriatal administration of glial cell line-derived neurotrophic factor (GDNF) restores striatal dopamine input in hemiparkinsonian rats. Since it has been found that GDNF is highly expressed in fetal kidney, we examined the possibility that fetal kidney tissue may provide trophic support, similar to GDNF, to an intranigral dopamine (DA) transplant and restore the nigrostriatal pathway. Adult Sprague-Dawley rats were anesthetized and unilaterally injected with 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. Completeness of the lesion was evaluated by measuring amphetamine-induced rotation. One month after 6-OHDA lesioning, fetal VM cells were grafted into the lesioned nigral area followed by transplantation of fetal kidney tissue or vehicle along a pathway from nigra to striatum. Animals receiving these transplants showed a significant decrease both in amphetamine-induced rotation and in postural asymmetry 1 to 3 months after grafting. Immunocytochemical studies demonstrated tyrosine hydroxylase (TH) positive fiber tracts in the lesioned striatum. Control animals that received vehicle injection after the intranigral graft or no transplantation showed no alterations in amphetamine-induced turning and no TH-positive fibers in the lesioned striatum. These results indicate that combinations of fetal nigral and kidney transplants may restore the nigrostriatal DA pathway in Parkinsonian rats. As fetal kidney contains a variety of trophic proteins, it may provide a synergistic admixture to optimally promote DA fiber outgrowth.     

Mesencephalic neural stem (progenitor) cells develop to dopaminergic neurons more strongly in dopamine-depleted striatum than in intact striatum

Epidermal growth factor (EGF)/fibroblast growth factor (FGF)-responsive stem (progenitor) cells from embryonic brain have self-renewing and multipotent properties and thus are good candidates for donor cells in neural transplantation. However, the survival and differentiation to mature neurons after grafting of stem cells into adult brain are rather poor. We hypothesize that the differentiation of stem cells to mature neurons, such as dopaminergic (DAergic) neurons, is dependent on environmental cues that control the ontogenic development. We compared the survival and differentiation between mesencephalic (MS) and cortical (CTx) stem (progenitor) cells, following grafting into bilateral striata of hemiparkinsonian model rats. MS and CTx stem cells were prepared from E12 rats and proliferated in serum-free medium with EGF or basic FGF for 2 weeks. One day after being primed to differentiate, the cell suspensions of both origins were grafted into the bilateral striata of adult rats that had unilateral 6-OHDA lesions in the substantia nigra. MS cells differentiated to tyrosine hydroxylase (TH)-positive neurons more strongly in DA-depleted striatum than in intact striatum, and methamphetamine-induced rotation was ameliorated in half of the grafted animals. Rosette-like cell aggregation and dysfunction of the blood-brain barrier (BBB) were less in and around the grafts in DA-depleted striatum, suggesting less proliferation and more differentiation of MS stem cells in DA-depleted striatum. Neither TH-positive neurons nor behavioral amelioration were detected following CTx stem (progenitor) cell transplantation in the striata. Data suggest that the DA-depleted striatum offers a suitable environment for MS stem (progenitor) cells to differentiate into mature DAergic neurons.     

如何提高帕金森病中脑细胞移植中的细胞存活率?

虽然胚胎中脑细胞移植对帕金森病的疗效已得到广泛证实,但在这项技术广泛应用于临床之前仍有一些问题亟待解决.其中主要是移植物存活率低和宿主纹状体神经支配恢复有限.迄今为止,人们尝试了很多方法来解决这些问题,包括神经营养因子的广泛应用,以及神经和(或)非神经来源组织的联合移植.本文将对目前的胚胎中脑细胞移植术中所用的神经保护手段及其局限性进行简要的介绍.     

Co-grafts of embryonic dopamine neurons and adult sciatic nerve into the denervated striatum enhance behavioral and morphological recovery in rats

We have recently demonstrated that a diffusible factor(s) derived from explanted adult rat sciatic nerve can increase the number and neurite outgrowth of embryonic rat dopamine (DA) neurons in culture. The present study extends this finding to compare DA neuron-sciatic nerve co-grafts to grafts of DA-rich neural tissue alone for behavioral and morphological effects in rats with unilateral nigrostriatal lesions of the DA pathway. Our results indicate that the presence of a co-grafted segment of sciatic nerve increased the likelihood of rapid behavioral recovery and promoted complete recovery mediated by small grafts that yielded only modest behavioral changes in the absence of co-grafted nerve. These behavioral effects were accompanied by a modest increase in survival of grafted tyrosine hydroxylase-positive neurons in the striatum and a more pronounced increase in the area and density of striatal reinnervation provided by grafted DA neurons in co-grafted animals. This evidence supports the view that a diffusible product of explanted peripheral nerve acts as a growth-promoting factor for embryonic DA neurons and that the presence of this factor augments the behavioral efficacy of grafted DA neurons.     

Oligodendrocyte-type 2 astrocyte-derived trophic factors increase survival of developing dopamine neurons through the inhibition of apoptotic cell death

Survival of embryonic dopamine (DA) neurons is extremely low (5-20%) following transplantation. Strategies to increase this survival are critical to the future of transplantation for Parkinson's disease. We demonstrate here that a factor(s) released from striatal oligodendrocyte-type 2 astrocytes (SO2A) greatly improves the survival and phenotype expression of mesencephalic DA neurons in culture while simultaneously decreasing the presence of apoptotic nuclear profiles, as detected by the TUNEL method and bisbenzamide/tyrosine hydroxylase double labeling. This SO2A-derived trophic factor(s) has minimal effects on glia and no effect on nondopaminergic mesencephalic neurons. The developmental period during which this SO2A trophic effect occurs (E14-18) coincides with the period when mesencephalic grafts are undergoing the highest rates of apoptosis, i.e., immediately following implantation. Therefore, SO2A-derived trophic factor(s) offers great potential for the augmentation of grafted DA neuron survival.     

Increased cell suspension concentration augments the survival rate of grafted tyrosine hydroxylase immunoreactive neurons

The poor survival rate (5-20%) of grafted embryonic dopamine (DA) neurons is one of the primary factors preventing cell replacement from becoming a viable treatment for Parkinson's disease. Previous studies have demonstrated that graft volume impacts grafted DA neuron survival, indicating that transplant parameters influence survival rates. However, the effects of mesencephalic cell concentration on grafted DA neuron survival have not been investigated. The current study compares the survival rates of DA neurons in grafts of varying concentrations. Mesencephalic cell suspensions derived from E14 Fisher 344 rat pups were concentrated to 25,000, 50,000, 100,000 and 200,000 cells/microl and transplanted into two 0.5 microl sites in the 6-OHDA-denervated rat striatum. Animals were sacrificed 10 days and 6 weeks post-transplantation for histochemical analysis of striatal grafts. The absolute number of DA neurons per graft increased proportionally to the total number of cells transplanted. However, our results show that the 200,000 cells/microl group exhibited significantly higher survival rates (5.48+/-0.83%) compared to the 25,000 cells/microl (2.81+/-0.39%) and 50,000 cells/microl (3.36+/-0.51%) groups (p=0.02 and 0.03, respectively). Soma size of grafted DA neurons in the 200,000 cells/microl group was significantly larger than that of the 25,000 cells/microl (p<0.0001) and 50,000 cells/microl groups (p=0.004). In conclusion, increasing the concentration of mesencephalic cells prior to transplantation, augments the survival and functionality of grafted DA neurons. These data have the potential to identify optimal transplantation parameters that can be applied to procedures utilizing stem cells, neural progenitors, and primary mesencephalic cells.     

Transplantation of Mesencephalic Cell Suspension in Dopamine-Denervated Striatum of the Rat: I. Effects on Spontaneous Activity of Striatal Neurons

These studies have examined the extent to which intrastriatal grafts of embryonic mesencephalic neurons induce recovery of normal discharge patterns in striatal neurons of rats after a unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal dopamine (DA) pathway. Lesioned rats were tested for rotational behavior induced by amphetamine and apomorphine. Animals which responded positively to these tests received two suspensions of mesencephalic embryonic neurons into the dorsal striatum (ST) ipsilateral to the denervated side. Sham-grafted rats received the suspension medium only. The vitality of the graft was assessed by the disappearance or reversion of rotational movements induced by amphetamine. Extracellular recordings of neurons located throughout the ST were carried out 3 months after grafting, when the animals reached the age of 6 months. The 6-OHDA-induced nigral lesion caused a net increase both in the number of striatal neurons spontaneously active and in their discharging rates. The signs of increased neuronal activity were also present in sham-grafted animals. The grafting of embryonal cells strongly reduced the number of active neurons and decreased significantly their discharging rate. The effects of the intrastriatal graft appeared to be present within a radius of 1.5–2 mm from the core of the grafted area. The presence of tyrosine-hydroxylase-immunopositive neurons innervating the host ST confirmed the viability of the grafts at the time of electrophysiological recording. The results show that besides compensating motor asymmetries caused by DA denervation, intrastriatally grafted dopaminergic neurons are able to only partially restore the electrophysiological action of DA in discrete striatal domains.