Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.14.16.2 (tyrosine hydroxylase)
 14,760 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neural progenitor cell grafting is a promising therapeutic option in the treatment of Parkinson's disease. In previous experiments we grafted temperature-sensitive immortalized CSM14.1 cells, derived from the ventral mesencephalon of E14-rats, bilaterally in the caudate putamen of adult hemiparkinsonian rats. In these studies we were not able to demonstrate either a therapeutic improvement or neuronal differentiation of transplanted cells. Here we examined whether CSM14.1 cells grafted bilaterally orthotopically in the substantia nigra of hemiparkinsonian rats have the potential to differentiate into dopaminergic neurons. Adult male rats received 6-hydroxydopamine into the right medial forebrain bundle, and successful lesions were evaluated with apomorphine-induced rotations 12 days after surgery. Two weeks after a successful lesion the animals received bilateral intranigral grafts consisting of either about 50 000 PKH26-labelled undifferentiated CSM14.1 cells (n = 16) or a sham-graft (n = 9). Rotations were evaluated 3, 6, 9 and 12 weeks post-grafting. Animals were finally perfused with 4% paraformaldehyde. Cryoprotected brain slices were prepared for immunohistochemistry using the freeze-thaw technique to preserve PKH26-labelling. Slices were immunostained against neuronal epitopes (NeuN, tyrosine hydroxylase) or glial fibrillary acidic protein. The CSM14.1-cell grafts significantly reduced the apomorphine-induced rotations 12 weeks post-grafting compared to the sham-grafts (P < 0.05). There was an extensive mediolateral migration (400-700 microm) of the PKH26-labelled cells within the host substantia nigra. Colocalization with NeuN or glial fibrillary acidic protein in transplanted cells was confirmed with confocal microscopy. No tyrosine hydroxylase-immunoreactive grafted cells were detectable. The therapeutic effect of the CSM14.1 cells could be explained either by their glial cell-derived neurotrophic factor-expression or their neural differentiation with positive effects on the basal ganglia neuronal networks.
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PMID:Orthotopic transplantation of immortalized mesencephalic progenitors (CSM14.1 cells) into the substantia nigra of hemiparkinsonian rats induces neuronal differentiation and motoric improvement. 1803 47

The pathogenesis of Parkinson's disease (PD) involves ongoing apoptotic loss of dopaminergic neurons in the substantia nigra pars compacta. Local delivery of the trophic factors can rescue dopaminergic neurons and halt the progression of PD. In this study we show that fetal E11 striatum-derived neurospheres and E14.5 ventral mesencephalon (VM) -derived neurospheres (NS E11 and NSvm, respectively) are a source of factors that rescue dopaminergic neurons. First, long-term expanded NS E11 and NSvm rescued primary dopaminergic neurons from serum-deprivation induced apoptosis and promoted survival of dopaminergic neurons for 14 days in vitro and this effect was due to soluble contact-independent factor/s. Second, green fluorescent protein-expressing NS E11 and NSvm grafted into the midbrain of mice with unilateral 6-hydroxydopamine-induced Parkinsonism resulted in partial rescue of the nigro-striatal system and improvement of the hypo-dopaminergic behavioral deficit. Reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrated that intact NS E11 and NSvm expressed fibroblast growth factor-2, brain-derived neurotrophic factor (BDNF), pleiotrophin, neurotrophin-3, but not glial cell line-derived neurotrophic factor (GDNF). GDNF expression was also undetectable in vivo in grafted NS E11 and NSvm suggesting that NS-derived factor/s other than GDNF mediated the rescue of nigral dopaminergic neurons. Identification of NS-derived soluble factor(s) may lead to development of novel neuroprotective therapies for PD. An unexpected observation of the present study was the detection of the ectopic host-derived tyrosine hydroxylase (TH) -expressing cells in sham-grafted mice and NS E11- and NSvm -grafted mice. We speculate that injury-derived signals (such as inflammatory cytokines that are commonly released during transplantation) induce TH expression in susceptible cells.
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PMID:Fetal striatum- and ventral mesencephalon-derived expanded neurospheres rescue dopaminergic neurons in vitro and the nigro-striatal system in vivo. 1847 26

Pramipexole, a dopamine D2/D3 receptor agonist used in the treatment of Parkinson's disease, has been reported to have neuroprotective potential. We investigated the effect of pramipexole against cell death induced by a proteasome inhibitor, lactacystin, using primary mecencephalic neuronal cultures and SH-SY5Y cells. In E14 rat primary mesencephalic cultures, the number of surviving tyrosine hydroxylase (TH)-positive neurons and microtubule associated protein 2 (MAP2)-positive neurons was decreased by exposure to 1-5 microM lactacystin in a dose-dependent manner. Pretreatment with 100 microM pramipexole rescued TH-positive neurons and MAP2-positive neurons from the toxicity of lactacystin. The protective effect of pramipexole was not selective for TH-positive dopaminergic neurons. However, the treatment with 100 microM pramipexole did not protect SH-SY5Y cells against lactacystin-induced cell toxicity and proteasome dysfunction. We hypothesized that the protective effect of pramipexole against the lactacystin-toxicity was not direct but a secondary effect mediated by astrocytes. Therefore, we investigated the efficacy of conditioned medium collected from mecencephalic astrocytes treated with pramipexole. The conditioned medium increased the viability of SH-SY5Y cells against the toxicity of lactacystin. Pramipexole increased the levels of brain derived neurotrophic factor (BDNF) in the conditioned medium of astrocyte cultures. These protective effects were not significantly inhibited by dopamine D2 or D3 receptor antagonists. We demonstrated that pramipexole had the protective effect against lactacystin toxicity, mediated by a neurotrophic effect of astrocyte-produced factors including BDNF.
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PMID:Pramipexole has astrocyte-mediated neuroprotective effects against lactacystin toxicity. 1855 4

The inadequate survival of dopamine neurons following intracerebral transplantation is in part attributed to the generation of reactive oxygen species and subsequent oxidative stress. To address this, we investigated whether the antioxidant ascorbic acid (vitamin C) had any effect on the yields of dopamine neurons derived from E14 rat ventral mesencephalic cells in vitro and in grafts. Following in vitro differentiation in medium containing ascorbic acid at concentrations ranging from 20 to 100 microM, significantly more neurons were immunopositive for the marker of mesencephalic dopamine neurons, tyrosine hydroxylase (TH), when compared to standard differentiation conditions containing no ascorbic acid. Mesencephalic cell suspensions supplemented with 100 microM ascorbic acid were also transplanted into unilateral 6-OHDA-lesioned rats and behavioral rotation was assessed at 2, 4, and 6 weeks posttransplantation. Grafts pretreated with ascorbic acid contained significantly more surviving dopamine neurons compared to nontreated grafts. However, no significant difference in rotation score was observed, with both groups showing a reversal and overcompensation of rotational bias. In addition, no evidence of neurogenesis of nigral dopamine neurons was observed in transplant groups. While the increased number of dopamine neurons observed in our study following ascorbic acid treatment may reflect a selective survival effect, our in vitro results suggest that ascorbic acid may act to increase the number dopamine neurons, both in culture and following transplantation, by stimulating dopaminergic differentiation of neural precursors from the fetal ventral mesencephalon.
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PMID:Ascorbic acid increases the number of dopamine neurons in vitro and in transplants to the 6-OHDA-lesioned rat brain. 1904 3

Transplantation of fetal dopaminergic (DA) neurons offers an experimental therapy for Parkinson's disease (PD). The low availability and the poor survival and integration of transplanted cells in the host brain are major obstacles in this approach. Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor with growth- and survival-promoting capabilities for developing DA neurons. In the present study, we examined whether pretreatment of ventral mesencephalic (VM) free-floating roller tube (FFRT) cultures with GDNF would improve graft survival and function. For that purpose organotypic cultures of E14 rat VM were grown for 2, 4 or 8 days in the absence (control) or presence of GDNF [10 ng/ml] and transplanted into the striatum of 6-hydroxydopamine-lesioned rats. While all groups of rats showed a significant reduction in d-amphetamine-induced rotations at 6 weeks posttransplantation a significantly improved graft function was observed only in the days in vitro (DIV) 4 GDNF pretreated group compared to the control group. In addition, no statistical significant differences between groups were found in the number of surviving tyrosine hydroxylase-immunoreactive (TH-ir) neurons assessed at 9 weeks posttransplantation. However, a tendency for higher TH-ir fiber outgrowth from the transplants in the GDNF pretreated groups as compared to corresponding controls was observed. Furthermore, GDNF pretreatment showed a tendency for a higher number of GIRK2 positive neurons in the grafts. In sum, our findings demonstrate that GDNF pretreatment was not disadvantageous for transplants of embryonic rat VM with the FFRT culture technique but only marginally improved graft survival and function.
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PMID:Effects of GDNF pretreatment on function and survival of transplanted fetal ventral mesencephalic cells in the 6-OHDA rat model of Parkinson's disease. 1938 87

Diadenosine tetraphosphate (AP(4)A), two adenosine moieties bridged by four phosphates, is an endogenous purinergic ligand found in brain. Previous studies have shown that AP(4)A reduced neurodegeneration caused by the dopaminergic neurotoxin 6-hydroxydopamine in rat striatum and substantia nigra. The purpose of this study was to determine whether AP(4)A is protective against methamphetamine (MA)-mediated toxicity. Primary neuronal cultures were prepared from rat embryonic (E14-E15) ventral mesencephalic tissue. Cultures treated with 2mM MA exhibited decreased tyrosine hydroxylase (TH) immunoreactivity and increased cleaved caspase-3 immunoreactivity and TUNEL labeling. All these changes were lessened by pretreatment with AP(4)A. The protective effect of AP(4)A was also found in vivo. Adult Sprague-Dawley rats were injected with AP(4)A (25 microg/20 microl) or vehicle intracerebroventricularly followed by 4 doses of MA (5 or 10 mg/kg), given subcutaneously every 2h. Administration of MA reduced locomotor activity 1 day after injection, which was significantly antagonized by the pretreatment with AP(4)A. Using immunohistochemical analysis, TH fiber density at the substantia nigra pars reticulata was found reduced while cleaved caspase-3 immunoreactivity in striatum was increased after MA treatment; these responses were also significantly antagonized by AP(4)A. Taken together, our data show that AP(4)A has protective effects against MA-mediated toxicity both in vitro and in vivo. The mechanism of action involves suppression of MA-induced apoptosis.
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PMID:Diadenosine tetraphosphate reduces toxicity caused by high-dose methamphetamine administration. 1944 29

Intracerebral transplantation of dopaminergic (DA) cells is currently further explored as a potential restorative therapy for Parkinson's disease (PD). However, before they can be considered for a more widespread clinical use a number of critical issues have to be resolved, including an optimized transplantation protocol. This study has been performed in a rat 6-hydroxydopamine model of PD and is based on the microtransplantation approach. The results demonstrate a reduced survival (threefold) for a single cell suspension of E14 rat ventral mesencephalon compared to a fragment suspension when a metal cannula is used for implantation. However, fragment suspensions result in a more variable graft survival and ectopically placed cells along the implantation tract. When a glass capillary is used for implantation, the survival of the single cell suspension (so-called "micrograft") improved by fourfold (vs. single cells/metal cannula) and is superior to the combination of the metal cannula and fragment suspension (+40%). The micrografts show a reduced variability in DA neuron survival as well as fewer ectopically placed cells. Moreover, the implantation time can significantly be reduced from 19 to 7 min in micrografted animals without a compromise in DA graft survival and functional behavioral outcome. Using the microtransplantation approach graft size can be tailored effectively by varying the density of the final cell suspension at least between 11,000 and 320,000 cells/microl, resulting in comparable survival of tyrosine hydroxylase (TH)-positive neurons in the range of 2-4%. With this approach no more than 100 surviving TH-positive neurons are necessary to produce functional effects in the amphetamine-induced rotation test. Interestingly, we found that DA micrografts into lesion striatum present 20% higher survival rates of TH neurons in comparison to the intact striatum. In summary, these results provide further evidence for the usefulness of the microtransplantation approach and allow for a more precise and tailored adaptation of the implantation parameters for further studies on DA, and possibly also other neural-, glial-, and stem cell-derived grafts.
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PMID:Microtransplantation of dopaminergic cell suspensions: further characterization and optimization of grafting parameters. 1949 1

Neural stem cell (NSC) transplantation has the potential to treat neurodegenerative diseases such as Parkinson's disease (PD). In this study, we investigated the effect of transplanted NSCs in a PD animal model. NSCs isolated from the subventricular zone (SVZ) of E14 rats were cultured in vitro to produce neurospheres, which were subsequently infected with recombinant adeno-associated virus (rAAV(2)) expressing enhanced green fluorescent protein (EGFP). The PD animal model was established by unilateral injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle (MFB) of Sprague-Dawley rats. Once the model was established, EGFP-expressing NSCs were transplanted into the substantia nigra pars compacta (SNc) or striatum of PD rats. We found that NSCs transplanted into either site significantly reduced apomorphine-induced circling behavior of PD rats. Pathological analysis revealed that the EGFP-expressing NSCs could be detected at both injection sites at 1, 2 and 4 months after transplantation. SNc transplanted cells dispersed within the SNc with a significant portion differentiated into tyrosine hydroxylase-positive neurons. Whereas cells transplanted into the striatum migrated ventrally and posteriorly towards the SNc. These results suggest that the 6-OHDA damaged brain area attracts grafted NSCs, which migrated from the striatum and survived for a long time in SNc, resulting in behavioral improvement of PD rats.
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PMID:Grafted neural stem cells migrate to substantia nigra and improve behavior in Parkinsonian rats. 1959 3

The modification of the neural cell adhesion molecule (NCAM) with polysialic acid plays a pivotal role in the developing nervous system. Here we studied the expression and function of polysialic acid during development of the mesencephalic dopaminergic system of mice. Using immunohistochemistry, polysialic acid was detected on nestin-positive radial glia processes and on cell somata in the pial zone of the midbrain at embryonic day E11.5 and E14.5. As studied by quantitative real-time RT-PCR, mRNA profiles of NCAM and the polysialyltransferases, ST8SiaII and ST8SiaIV, matched the course of tyrosine hydroxylase, dopamine transporter, nur-related factor 1, and paired-like homeodomain transcription factor 3 expression, which were used as marker genes of dopaminergic development. Asking for a possible role of polysialylation during formation of the dopaminergic system, mice lacking polysialic acid because of ablation of both St8siaII and St8siaIV were analyzed at selected time points by tyrosine hydroxylase immunohistochemistry and by real-time RT-PCR of dopaminergic markers. Surprisingly, no differences between wild-type and mutant mice could be detected. Likewise, enzymatic removal of polysialic acid from cultured neurons of the ventral embryonic midbrain had no effect on the expression of dopaminergic marker genes. We conclude that despite its abundance polysialic acid is dispensable for the formation of the mesencephalic dopaminergic system.
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PMID:NCAM and polysialyltransferase profiles match dopaminergic marker gene expression but polysialic acid is dispensable for development of the midbrain dopamine system. 1961 34

In addition to the well-characterized direct and indirect projection neurons there are four major interneuron types in the striatum. Three contain GABA and either parvalbumin, calretinin or NOS/NPY/somatostatin. The fourth is cholinergic. It might be assumed that dissociated cell cultures of striatum (typically from embryonic day E18.5 in rat and E14.5 for mouse) contain each of these neuronal types. However, in dissociated rat striatal (caudate/putamen, CPu) cultures arguably the most important interneuron, the giant aspiny cholinergic neuron, is not present. When dissociated striatal neurons from E14.5 Sprague-Dawley rats were mixed with those from E18.5 rats, combined cultures from these two gestational periods yielded surviving cholinergic interneurons and representative populations of the other interneuron types at 5 weeks in vitro. Neurons from E12.5 CD-1 mice were combined with CPu neurons from E14.5 mice and the characteristics of striatal interneurons after 5 weeks in vitro were determined. All four major classes of interneurons were identified in these cultures as well as rare tyrosine hydroxylase positive interneurons. However, E14.5 mouse CPu cultures contained relatively few cholinergic interneurons rather than the nearly total absence seen in the rat. A later dissection day (E16.5) was required to obtain mouse CPu cultures totally lacking the cholinergic interneuron. We show that these cultures generated from two gestational age cells have much more nearly normal proportions of interneurons than the more common organotypic cultures of striatum. Interneurons are generated from both ages of embryos except for the cholinergic interneurons that originate from the medial ganglionic eminence of younger embryos. Study of these cultures should more accurately reflect neuronal processing as it occurs in the striatum in vivo. Furthermore, these results reveal a procedure for parallel culture of striatum and cholinergic depleted striatum that can be used to examine the function of the cholinergic interneuron in striatal networks.
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PMID:Striatal interneurons in dissociated cell culture. 2049 May 35


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