IL-1β is released from the host brain following transplantation but does not compromise embryonic dopaminergic neuron survival

Poor survival of transplanted dopaminergic (DA) neurons remains a serious obstacle to the success of cell replacement therapy as an alternative to the current treatments for Parkinson's disease. We have examined the temporal release profile of an inflammatory cytokine, interleukin-1 beta (IL-1 beta) following transplantation of fetal mesencephalic tissue into the rat striatum. The amounts of IL-1 beta released in vivo when added to cultures of embryonic DA neurons, did not significantly reduce the survival of DA neurons in vitro, and inclusion of the naturally-occurring IL-1 receptor antagonist, IL-1ra, did not appear to affect the numbers of surviving DA neurons present after 5 days in vitro. Neither did inclusion of IL-1ra in cell suspensions during transplantation increase the survival of transplanted fetal DA neurons. Thus, although IL-1 beta is released following implantation of a neural transplant, we suggest that this pro-inflammatory cytokine does not play an active role in reducing survival of transplanted DA neurons, unlike other cytokines such as tumor necrosis factor alpha. Modulation of IL-1 beta activity, therefore, will not offer significant improvements to neural transplantation as a treatment for PD.     

A role for tumor necrosis factor alpha in death of dopaminergic neurons following neural transplantation

Poor survival of transplanted dopaminergic (DA) neurons remains a serious obstacle to the success of cell replacement therapy as an alternative to the current treatments for Parkinson's disease (PD). We have examined the temporal release profile of an inflammatory cytokine, tumor necrosis factor-alpha (TNFalpha), following transplantation of fetal mesencephalic tissue into the rat striatum. The amounts of TNFalpha released in vivo when added to cultures of embryonic DA neurons, significantly reduced the survival of DA neurons in vitro, and this cell death could be prevented by the inclusion of an antibody to the TNFalpha receptor type 1. Inclusion of this antibody in cell suspensions during transplantation also increased the survival of transplanted fetal DA neurons by approximately 250%. Use of this therapeutic antibody approach may offer significant improvements to neural transplantation as a treatment for PD.     

Zuckerkandl's organ improves long-term survival and function of neural stem cell derived dopaminergic neurons in Parkinsonian rats

Transplantation of neural stem cells (NSC) derived dopamine (DA) neurons has emerged as an alternative approach to fetal neural cell transplantation in Parkinson's disease (PD). However, similar to fetal neural cell, survival of these neurons following transplantation is also limited due to limited striatal reinnervation (graft with dense neuronal core), limited host-graft interaction, poor axonal outgrowth, lack of continuous neurotrophic factors supply and principally an absence of cell adhesion molecules mediated appropriate developmental cues. In the present study, an attempt has been made to increase survival and function of NSC derived DA neurons, by co-grafting with Zuckerkandl's organ (a paraneural organ that expresses neurotrophic factors as well as cell adhesion molecules); to provide continuous NTF support and developmental cues to transplanted DA neurons in the rat model of PD. 24 weeks post transplantation, a significant number of surviving functional NSC derived DA neurons were observed in the co-transplanted group as evident by an increase in the number of tyrosine hydroxylase immunoreactive (TH-IR) neurons, TH-IR fiber density, TH-mRNA expression and TH-protein level at the transplantation site (striatum). Significant behavioral recovery (amphetamine induced stereotypy and locomotor activity) and neurochemical recovery (DA-D2 receptor binding and DA and DOPAC levels at the transplant site) were also observed in the NSC+ZKO co-transplanted group as compared to the NSC or ZKO alone transplanted group. In vivo results were further substantiated by in vitro studies, which suggest that ZKO increases the NSC derived DA neuronal survival, differentiation, DA release and neurite outgrowth as well as protects against 6-OHDA toxicity in co-culture condition. The present study suggests that long-term and continuous NTF support provided by ZKO to the transplanted NSC derived DA neurons, helped in their better survival, axonal arborization and integration with host cells, leading to long-term functional restoration in the rat model of PD.     

Apoptosis in primary cultures of E14 rat ventral mesencephala: time course of dopaminergic cell death and implications for neural transplantation

Transplantation using fetal nigral grafts has been performed by various groups worldwide in over 200 Parkinson's disease (PD) patients in an attempt to restore dopaminergic (DA) input to the striatum. However, the proportion of the implanted DA neurons that survives, whether using suspension, partially dissociated, or solid grafts, is small, often as low as 5 to 10%, which is insufficient to allow a full functional recovery. A significant proportion of the transplanted neurons in animal models of PD has been shown to die via apoptosis, but the reason for this is unclear. Since the methods used to prepare donor tissue for neural transplantation and in vitro culture are identical, we have looked at the time course of DA neuron loss following cell suspension preparation using an in vitro assay system and considered whether the procedures used may, in part, be responsible for the poor DA neuron survival. Primary dissociated cultures of E14 rat ventral mesencephala were incubated for different periods in serum-containing and serum-free media. After fixation, the TUNEL method, as well as ethidium bromide and acridine orange, were used to detect apoptosis, and DA neurons were localized immunocytochemically. Results showed that most apoptosis occurred during the first 24 h and that 50% of the DA neurons were lost in the first 8 h. Double-immunofluorescent labeling confirmed the presence of TUNEL+ve nuclei within DA neurons. There was no difference in either the extent or rate of loss between the serum-containing and serum-free medium during the first 32 h. We suggest, therefore, that existing methods used to prepare cell suspensions probably induce apoptosis and may need to be modified in order to increase the survival of DA neurons.     

Apoptosis in neuronal development and transplantation: role of caspases and trophic factors

Fetal ventral mesencephalic (VM) transplants have been studied in the context of dopaminergic (DA) replacement therapy for Parkinson's disease (PD). DA neurons from VM transplants will grow axons and form functional synapses in the adult host central nervous system (CNS). Recently, studies have demonstrated that most of the transplanted DA neurons die in grafts within the first week after implantation. An important feature of neural development, also in transplanted developing fetal neural tissue, is cell death. However, while about 50% of cells born in the CNS will die naturally, up to 99% of fetal cells die after neural transplantation. It has been shown that VM grafts contain many apoptotic cells even at 14 days after transplantation. The interleukin-1beta converting enzyme (ICE) cysteine protease and 11 other ICE-like-related proteases have been identified, now named caspases. Activation of caspases is one of the final steps before a neuron is committed to die by apoptosis. Here we review this cell death process in detail: Since the growth of fetal neural grafts placed in the adult brain in many ways mimics normal development, it is likely that the caspases also play a functional role in transplants. Pharmacological inhibitors of caspases and genetically modified mice are now available for the study of neuronal death in fetal neuronal transplants. Understanding cell death mechanisms involved in acute cellular injury, necrosis, and programmed cell death (PCD) is useful in improving future neuronal transplantation methodology, as well as in neuroprotection, for patients with neurodegenerative diseases.     

Effects of IL-1beta, IL-6 or LIF on rat sensory neurons co-cultured with fibroblast-like cells.

Inflammation may affect the local presence of sensory nerve fibers in situ and inflammatory mediators influence sensory neurons in vitro. In the present study we have investigated effects of the cytokines interleukin-1beta (IL-1beta, interleukin-6 (IL-6), and leukemia inhibitory factor (LIF) on survival of and neurite growth from neonatal rat sensory neurons co-cultured with fibroblast-like cells prepared from neonatal rat skin (sFLCs) or perichondrium (pFLCs). The results showed that both FLC types expressed receptors for all three cytokines. Five ng/ml of either cytokine, but not lower or higher concentrations, supported survival of DRG neurons co-cultured with sFLCs. Neuronal survival was also enhanced by addition of the soluble IL-6 receptor (rsIL-6R) with or without IL-6. In co-cultures with pFLCs neuronal survival was promoted by IL-6, increasing with cytokine concentration. Addition of rsIL-6R without IL-6 did also stimulate neuronal survival. The growth of neurites from DRG neurons co-cultured with sFLCs was stimulated by 0.5 ng/ml LIF, unaffected by 5 ng/ml LIF and inhibited by 50 ng/ml LIF. Considering DRG neurons co-cultured with pFLCs, 50 ng/ml of either of the three cytokines, as well as rsIL-6R conditioned medium, stimulated neurite outgrowth. Some of the cytokine effects observed were reduced by application of antibodies against nerve growth factor (NGF). We conclude that that the cytokines examined affect DRG neurons in terms of survival or neuritogenesis, that the effects are influenced by cytokine concentration and the origin of the FLCs and that some of the effects are indirect, probably being mediated by factors released from FLCs.     

Inhibition of kainic acid induced expression of interleukin-1 beta and interleukin-1 receptor antagonist mRNA in the rat brain by NMDA receptor antagonists

The cytokines interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1ra) are rapidly induced in response to excitotoxic and ischemic brain damage. The aim of the present study was to investigate the influence of a non-competitive (dizocilpine maleate, MK-801) and a competitive ((R)-CPP) NMDA receptor antagonist on the transient cytokine expression in the rat brain induced by systemic kainic acid administration. Peripheral administration of kainic acid (10 mg/kg, i.p.) results in a transient expression of IL-1 beta and IL-1ra mRNA, mainly in microglia, in regions showing neurodegeneration such as the hippocampus, thalamus, amygdala, and certain cortical regions. In addition, a few neurons expressing IL-1ra mRNA were observed in the piriform cortex and amygdala following kainic acid injection. Administration of MK-801 (i.p.) 1 h prior to kainic acid injection reduced cytokine expression in all of these regions. MK-801 at 3.0 mg/kg decreased the IL-1 beta mRNA expression, blocked or decreased the IL-1ra mRNA expression, depending on the brain region. MK-801 at 5.0 mg/kg abolished IL-1ra mRNA expression in all of the regions, whereas the IL-1 beta mRNA expression was decreased or blocked, depending on the brain region, or the time point investigated. Peripheral administration of (R)-CPP (15 mg/kg, i.p.) 15 min prior to the kainic acid injection abolished the IL-1 beta mRNA expression. The IL-1ra mRNA expression was abolished in all regions except for a few neurons in the piriform cortex. The finding that NMDA receptor antagonists inhibit the IL-1 beta and IL-1ra mRNA synthesis induced by kainic acid suggests that NMDA receptor activation may be involved in triggering cytokine synthesis following excitotoxic brain damage.     

Interleukin-1beta exacerbates and interleukin-1 receptor antagonist attenuates neuronal injury and microglial activation after excitotoxic damage in organotypic hippocampal slice cultures

The effects of interleukin (IL)-1beta and IL-1 receptor antagonist (IL-1ra) on neurons and microglial cells were investigated in organotypic hippocampal slice cultures (OHSCs). OHSCs obtained from rats were excitotoxically lesioned after 6 days in vitro by application of N-methyl-D-aspartate (NMDA) and treated with IL-1beta (6 ng/mL) or IL-1ra (40, 100 or 500 ng/mL) for up to 10 days. OHSCs were then analysed by bright field microscopy after hematoxylin staining and confocal laser scanning microscopy after labeling of damaged neurons with propidium iodide (PI) and fluorescent staining of microglial cells. The specificity of PI labeling of damaged neurons was validated by triple staining with neuronal and glial markers and it was observed that PI accumulated in damaged neurons only but not in microglial cells or astrocytes. Treatment of unlesioned OHSCs with IL-1beta did not induce neuronal damage but caused an increase in the number of microglial cells. NMDA lesioning alone resulted in a massive increase in the number of microglial cells and degenerating neurons. Treatment of NMDA-lesioned OHSCs with IL-1beta exacerbated neuronal cell death and further enhanced microglial cell numbers. Treatment of NMDA-lesioned cultures with IL-1ra significantly attenuated NMDA-induced neuronal damage and reduced the number of microglial cells, whereas application of IL-1ra in unlesioned OHSCs did not induce significant changes in either cell population. Our findings indicate that: (i) IL-1beta directly affects the central nervous system and acts independently of infiltrating hematogenous cells; (ii) IL-1beta induces microglial activation but is not neurotoxic per se; (iii) IL-1beta enhances excitotoxic neuronal damage and microglial activation and (iv) IL-1ra, even when applied for only 4 h, reduces neuronal cell death and the number of microglial cells after excitotoxic damage.     

Blockade by interleukin-1 receptor antagonist of IL-1 beta-induced neuronal activity in guinea pig preoptic area slices.

Interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta) are thought to be endogenous pyrogens, i.e., to mediate fever production; warm-sensitive (W) and cold-sensitive (C) neurons in the preoptic area (POA) are presumed to be the ultimate targets of endogenous pyrogens. The recent purification of an IL-1 receptor antagonist (IL-1ra) has provided a means for verifying the presumptive action of IL-1 on these neurons. This study was undertaken, therefore, to investigate whether IL-1ra may block the IL-1 alpha and IL-1 beta effects on the firing rates (FR) of W and C neurons in guinea pig POA slices. Human recombinant (hr) IL-1 beta (500 ng/ml) reduced the FR of 26 W neurons and increased those of 3 C neurons recorded; it had no effect on 8 thermally insensitive neurons. hrIL-1 alpha (200-600 ng/ml) did not change the FR of any neuron. IL-Ira (0.01-0.5 mg/ml) had no effect by itself on the FR of all the neurons, but it blocked the hrIL-1 beta-induced FR changes of 24 of the 26 W and of all 3 C neurons when given before the cytokine. The lowest effective dose was 0.05 mg/ml. These results support the hypothesis, therefore, that POA thermosensitive neurons may be direct targets of IL-1 beta and that it may be an endogenous pyrogen acting on these units to induce fever production.     

Neurturin enhances the survival of intrastriatal fetal dopaminergic transplants.

We investigated here the effect of the novel glial cell line-derived neurotrophic factor (GDNF)-family member neurturin (NTN) on transplanted fetal dopamine (DA) neurons. Three groups of rats with complete unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal DA system received intrastriatal grafts of embryonic ventral mesencephalic tissue. Following transplantation animals received repeated injections of vehicle or NTN (0.3 microg or 3.0 microg) over three weeks posttransplantation. NTN-treated animals had significantly (1.8-fold) more tyrosine hydroxylase-immunoreactive (TH-IR) neurons. Graft volume, TH-IR cell volume and overall dopaminergic host reinnervation remained unchanged. Amphetamine-induced rotation was rapidly compensated in all grafted rats. We conclude that administration of NTN may be a powerful way to increase survival of transplanted fetal DA neurons.     

Cytokine activity contributes to induction of inflammatory cytokine mRNAs in spinal cord following contusion

Injury of the spinal cord leads to an inflammatory tissue response, probably mediated in part by cytokines. Because a common therapy for acute spinal cord injury is the use of an antiinflammatory synthetic glucocorticoid (methylprednisolone), we sought to determine mechanisms contributing to inflammation shortly after acute injury. Cytokine mRNAs [interleukin (IL)-1alpha, IL-1beta, tumor necrosis factor (TNF)-alpha, and IL-6] were increased during the first 2 hr following weight-drop compression injury by RNase protection assay, prior to the reported appearance of circulating lymphocytes. This immediate pattern of cytokine mRNA induction could be replicated in cultured, explanted spinal cord slices but not in whole blood of injured animals, which is consistent with a tissue source of cytokine mRNAs. Western blotting detected IL-1beta-like immunoreactivity released into culture medium following explantation and pro-IL-1beta-like immunoreactivity in freshly dissected spinal cord tissue. Pharmacologically blocking IL-1 and TNF-alpha receptors significantly reduced expression of IL-1alpha, IL-1beta, and TNF-alpha mRNAs. Finally, mice lacking both IL-1 and TNF-alpha receptors exhibited diminished induction of TNF-alpha, IL-6, and IL-1ra mRNAs following injury. Therefore, we conclude that contusion injury induces an immediate release of cytokines, which then contributes to the induction of cytokine mRNAs.     

Immune or inflammatory response by the host brain suppresses neuronal differentiation of transplanted ES cell-derived neural precursor cells

Embryonic stem (ES) cells are a promising donor source for transplantation therapy, but several problems must be solved before they can be clinically useful. One of these is the host immune reaction to allogeneic grafts. In this article, we examine the effect of the host immune reaction on survival and differentiation of grafted ES cell-derived neural precursor cells (NPCs). We induced NPCs from mouse ES cells by stromal cell-derived inducing activity and then transplanted them into mouse brains with or without administering the immunosuppressant cyclosporine A (CsA). Two and 8 weeks following transplantation, the accumulation of host-derived microglia/macrophages and lymphocytes was observed around the graft. This effect was reduced by CsA treatment, although no significant difference in graft volume was observed. These data suggest that an immune response occurs in allografts of ES cell-derived NPCs. Intriguingly, however, the ratio of neurons to astrocytes in the graft was higher in immunosuppressed mice. Because inflammatory or immune cells produce various cytokines, we examined the effect of IL-1beta, IL-6, IFN-gamma, and TNF-alpha on the differentiation of NPCs in vitro. Only IL-6 promoted glial cell fate, and this effect could be reversed by the addition of an IL-6 neutralizing antibody. These results suggest that allogeneic ES cell-derived NPCs can cause an immune response by the host brain, but it is not strong enough to reject the graft. More important, activated microglia and lymphocytes can suppress neuronal differentiation of grafted NPCs in vivo by producing cytokines such as IL-6.     

Sertoli cells enhance the survival of co-transplanted dopamine neurons

One of the major issues in neural transplantation is the low survival rate (<5%) of transplanted dopamine (DA) neurons [3]. Recently it has been shown that it is possible to enhance the survival of these neurons, which in turn may decrease the amount of tissue that is required for each transplantation patient. The present paper demonstrates a novel approach for enhancing neuronal survival by co-transplantation of neuronal tissue with Testis-derived Sertoli cells (SC). This strategy could improve neuronal survival through the provision of trophic support.     

Neuromodulation for Parkinson's disease]

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of midbrain dopaminergic (DA) neurons and a subsequent reduction in striatal dopamine. As a treatment for advanced Parkinson's disease, deep brain stimulation (DBS) of the thalamus was introduced in 1987 to treat tremor, and was applied in 1993 to the subthalamic nucleus. Now high-frequency stimulation of the subthalamic nucleus has become a surgical therapy of choice. Another surgical treatment is a cell replacement therapy. Transplantation of fetal dopaminergic (DA) neurons can produce symptomatic relief, however, the technical and ethical difficulties in obtaining sufficient and appropriate donor fetal brain tissue have limited the application of this therapy. Then, neural precursor cells and embryonic stem (ES) cells are expected to be candidates of potential donor cells for transplantation. We induced DA neurons from monkey ES cells, and analyzed the effect of transplantation of the DA neurons into MPTP-treated monkeys as a primate model of Parkinson's disease. Behavioral studies and functional imaging revealed that the transplanted cells functioned as DA neurons, attenuating the MPTP-induced neurological symptoms. DA neurons have also been generated from several human ES cell lines. Furthermore, functional recovery of rat PD models after transplantation was observed. One of the major problems in ES cell transplantation is tumor formation, which is caused by a small fraction of undifferentiated ES cells in the graft. So, it is essential for undifferentiated ES cells to be eliminated from the graft in order for transplantation to be feasible. These efforts will lead to clinical application of ES cell transplantation to the patients with PD.     

Systemic Interleukin-1beta stimulates the simultaneous release of norepinephrine in the paraventricular nucleus and the median eminence

Interleukin-1beta (IL-1beta), a cytokine with pronounced central effects such as fever, anorexia, analgesia, etc., is also known to activate the hypothalamo-pituitary-adrenal (HPA) axis. Corticotropin releasing hormone (CRH) neurons located in the hypothalamus are important for HPA activation. The cell bodies of CRH neurons are located in the paraventricular nucleus (PVN) and their terminals are present in the median eminence (ME). Although the catecholamines, norepinephrine (NE) and dopamine (DA) are believed to be crucial factors in the stimulation of CRH neurons, it is not clear if they affect the cell bodies or terminals of these neurons to cause HPA activation. This study was done to determine if IL-1beta affects NE and DA release at the level of CRH cell bodies or their terminals. Adult male Sprague-Dawley rats were implanted with two push-pull cannulae, one in the PVN and another in the ME, and were subjected to push-pull perfusion. They were treated either with 0, 1 or 5 microg of IL-1beta. Perfusates were collected for 2 h after treatment and analyzed for NE concentrations using HPLC-EC. NE levels in the control and low dose groups did not change significantly during the entire period of observation both in the PVN and ME. In contrast, treatment with 5 microg of IL-1beta produced a marked increase in NE release in the PVN at 20 and 40 min post-treatment. NE release in the ME increased from 10 to 140 min post-treatment. There were no significant changes in the release of DA from both these areas. These results indicate that IL-1beta increases NE levels both in the PVN and in the ME and this could be a possible mechanism by which it stimulates the HPA axis.     

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.     

联合培养胚鼠的黑质及纹状体LGE细胞脑内移植治疗帕金森病大鼠的实验研究

目的　观察并检测胚鼠纹状体外侧节突 (LGE)对多巴胺能 (DA)细胞存活性的促进和营养导向作用。方法　将帕金森病 (PD)模型随机分成四组 :Co -culture组 (n =12 ) ;Cograft组 (n =12 ) ;Solo -VM组 (n =12 ) ;Con trol组 (n =8)。将胚鼠LGE细胞和腹侧中脑组织 (VM )制成细胞悬液 ,植入Control组外的其他各组动物的尾壳核。 2周后进行PD鼠行为学检测 ,连续观察 2 4周 ,继之将各组大鼠处死 ,进行免疫组化染色。结果　Co -culture组和Co - graft组大鼠移植后旋转行为较Solo -VM组大鼠明显减少。CO -culture组和CO - graft组之间大鼠的旋转行为比较 ,无统计学差异。免疫组化观察证实LGE和VM离体培养移植和新鲜移植均能提高DA细胞的存活性 ,增加宿主纹状体内DA纤维重新支配的密度 ,并形成明显的DA细胞团。结论　LGE细胞对VM移植物有明显的营养导向作用 ,并可增强DA细胞的存活 ,促进移值后DA细胞功能持久维持 ,并增加DA细胞再支配的密度     

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。     

NGF和FGF对移植的兔5-HT、DA能性神经元的影响

本实验将含有5—HT和DA能性神经元的胎兔脑组织微块液用立体定向法移植至成年兔脑内。兔21只分为三组,每组7只:第一组加入NGF,第二组加FGF,第三组未加任何因子列为对照组。移植2个月后用高效液相色谱电化学法(HPLC-EC)测定移植神经元的递质(5-HT、DA)含量。结果显示1、2两组的5-HT和第二组DA含量均显著高于对照组(P<0.05,P<0.01)。因此,表明NGF和FGF可能具有促进移植神经元存活和分化的功能。     

Contribution of activated interleukin receptors in trigeminal ganglion neurons to hyperalgesia via satellite glial interleukin-1beta paracrine mechanism

The present study investigated whether under in vivo conditions, inflammation alters the excitability of nociceptive Adelta-trigeminal ganglion (TRG) neurons innervating the facial skin via a cytokine paracrine mechanism. We used extracellular electrophysiological recording with multibarrel-electrodes in this study, and complete Freund's adjuvant (CFA) was injected into the rat facial skin. The threshold for escape from mechanical stimulation applied to the whisker pad area in inflamed rats (2 days after CFA injection) was significantly lower than that in control rats. A total of 45 Adelta-nociceptive-TRG neurons responding to electrical stimulation of the whisker pad were recorded in pentobarbital-anesthetized rats. The number of Adelta-TRG neurons with spontaneous firings and their firing rate in inflamed rats were significantly larger than those in control rats. The firing rates of the Adelta-TRG neuronal spontaneous activity were current-dependently decreased by local iontophoretic application of an interleukin I receptor type I antagonist (IL-1ra) in inflamed rats, but not in controls, and current-dependently increased by iontophoretic application of interleukin 1beta (IL-1beta) in both control and inflamed rats. IL-1ra also inhibited Adelta-TRG neuron activity evoked by mechanical stimulation in the inflamed rats. The mechanical threshold of nociceptive-TRG neurons in inflamed rats was significantly lower than that in control rats, but was not significantly different between control and inflamed rats after application of an IL-1ra. These results suggested that inflammation modulates the excitability of nociceptive Adelta-TRG neurons innervating the facial skin via IL-1beta paracrine action within trigeminal ganglia. Such an IL-1beta release could be important in determining trigeminal inflammatory hyperalgesia.