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Neuronal Phenotype (neuronal + phenotype)
Selected AbstractsDepolarization promotes GAD 65-mediated GABA synthesis by a post-translational mechanism in neural stem cell-derived neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2008Nidhi Gakhar-Koppole Abstract Neuronal activity regulates neurogenesis and neuronal differentiation in the mammalian brain. The commencement of neurotransmitter expression establishes the neuronal phenotype and enables the formation of functional connectivity between neurons. In addition, release of neurotransmitters from differentiating neurons may modulate the behaviour of neural precursors. Here, we show that neuronal activity regulates ,-aminobutyric acid (GABA) expression in neurons generated from stem cells of the striatum and adult subventricular zone (SVZ). Differentiating neurons display spontaneous Ca2+ events, which are voltage-gated calcium channel (VGCC) dependent. Depolarization increases both the frequency of Ca2+ transients and the amount of Ca2+ influx in differentiating neurons. We show that depolarization-dependent GABA expression is regulated by the amplitude and not by the frequency of Ca2+ influx. Brief activation of VGCCs leads to Ca2+ influx that in turn promotes a rapid expression of GABA. Depolarization-dependent GABA expression does not require changes in gene expression. Instead, it involves cAMP-dependent protein kinase (PKA) and Ca2+ and phospholipid-dependent protein kinase (PKC) signalling. Activity increases the number of glutamic acid decarboxylase (GAD) 65-immunoreactive neurons in a PKA-dependent manner, without altering the expression of GAD 65, suggesting that depolarization promotes recruitment of GAD 65 by a post-translational mechanism. In line with this, depolarization does not permanently increase the expression of GABA in neurons derived from neural stem cells of the embryonic striatum, cortex and adult SVZ. Thus, neuronal activity does not merely accelerate neuronal differentiation but it may alter the mechanism of GABA synthesis in newly generated neurons. [source] Functional dentate gyrus neurogenesis in a rapid kindling seizure modelEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2006Paul D. Smith Abstract Neurogenesis in the adult mammalian hippocampus resulting in long-term persistence of new neurons with features of capacity for functional activation is recognized. Many stimuli are capable of increasing the rate of neurogenesis, including seizure activity. Whether these insults result in an increased number of new functionally active neurons over and above the baseline rate of neurogenesis is not known. The rapid electrical amygdala kindling (REAK) model of seizures isolates the effects of seizures alone in the absence of neuronal death and the resulting seizures induce expression of c-Fos in the vast majority of dentate gyrus (DG) granule cells. C57BL/6 mice were exposed to REAK then injected with bromodeoxyuridine (BrDU) to label dividing cells, then re-exposed to REAK after a delay period to allow detection of functional activation in new neurons by measurement c-Fos expression in response to seizures. Adult subgranular zone cells migrated into the DG granule cell layer (GCL), assumed a neuronal phenotype and demonstrated seizure-dependent responsiveness. Larger absolute numbers of new neurons demonstrating seizure-dependent activation were found in the GCL of previously kindled mice. Seizures are capable of increasing the number of new neurons with the capacity for functional activation laid down in the postseizure period and incorporated into seizure-activated circuitry. [source] Expression of functional NR1/NR2B-type NMDA receptors in neuronally differentiated SK-N-SH human cell lineEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2002Marina Pizzi Abstract The present study demonstrates that human SK-N-SH neuroblastoma cells, differentiated by retinoic acid (RA), express functional NMDA receptors and become vulnerable to glutamate toxicity. During exposure to RA, SK-N-SH cells switched from non-neuronal to neuronal phenotype by showing antigenic changes typical of postmitotic neurons together with markers specific for cholinergic cells. Neuronally differentiated cells displayed positive immunoreactivity to the vesicular acetylcholine transporter and active acetylcholine release in response to depolarizing stimuli. The differentiation correlated with the expression of NMDA receptors. RT-PCR and immunoblotting analysis identified NMDA receptor subunits NR1 and NR2B, in RA-differentiated cultures. The NR1 protein immunolocalized to the neuronal cell population and assembled with the NR2B subunit to form functional N -methyl- d -aspartate (NMDA) receptors. Glutamate or NMDA application, concentration-dependently increased the intracellular Ca2+ levels and acetylcholine release in differentiated cultures, but not in undifferentiated SK-N-SH cells. Moreover, differentiated cultures became vulnerable to NMDA receptor-mediated excitotoxicity. The glutamate effects were enhanced by glycine application and were prevented by the NMDA receptor blocker MK 801, as well as by the NR2B selective antagonist ifenprodil. These data suggest that SK-N-SH cells differentiated by brief treatment with RA may represent an unlimited source of neuron-like cells suitable for studying molecular events associated with activation of human NR1/NR2B receptors. [source] Postnatal neurogenesis in the dentate gyrus of the guinea pigHIPPOCAMPUS, Issue 3 2005Sandra Guidi Abstract In all species examined, the dentate gyrus develops over an extended period that begins during gestation and continues up to adulthood. The aim of this study was to investigate the pattern of postnatal cell production in the dentate gyrus of the guinea pig, a rodent whose brain development has features more closely resembling the human condition than the most commonly used rodents (rat and mouse). Animals of different postnatal (P) ages received one or multiple injections of bromodeoxyuridine (BrdU), and the number of labeled cells in the dentate gyrus was counted after time intervals of 24 h or longer. The total granule cell number and the volume of the granule cell layer were evaluated in Nissl-stained brain sections from P1 and P30 animals. P1,P5 animals were treated with MK-801 to analyze the effect of NMDA receptor blockade on cell proliferation. Cell production occurred at a high rate (9,000,13,000 labeled cells 24 h after one injection) from P1 to P20, with a peak at 3,6 days of age, and then slowly declined from P20 to P30. The production of new cells continued in adult animals, although at a much-reduced rate (400 cells 24 h after one injection). About 20% of the labeled cells survived after a 17-day period and most (60%) of these cells had a neuronal phenotype. The total number of granule cells increased over the first postnatal month; in 30-day-old animals, it was 20% greater than in 1-day-old animals. Administration of MK-801 to P1,P5 animals caused an increase in cell proliferation restricted to the dorsal dentate gyrus. The present data show that, although the guinea pig dentate gyrus develops largely before birth, the production of new neurons continues at a high rate during the first postnatal month, leading to a considerable increase in cell number. This developmental pattern, resembling the human and nonhuman primate condition, may make the guinea pig a useful rodent model in developmental studies on dentate gyrus neurogenesis. © 2004 Wiley-Liss, Inc. [source] Novel stem/progenitor cells with neuronal differentiation potential reside in the leptomeningeal nicheJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 9b 2009Francesco Bifari Abstract Stem cells capable of generating neural differentiated cells are recognized by the expression of nestin and reside in specific regions of the brain, namely, hippocampus, subventricular zone and olfactory bulb. For other brain structures, such as leptomeninges, which contribute to the correct cortex development and functions, there is no evidence so far that they may contain stem/precursor cells. In this work, we show for the first time that nestin-positive cells are present in rat leptomeninges during development up to adulthood. The newly identified nestin-positive cells can be extracted and expanded in vitro both as neurospheres, displaying high similarity with subventricular zone,derived neural stem cells, and as homogeneous cell population with stem cell features. In vitro expanded stem cell population can differentiate with high efficiency into excitable cells with neuronal phenotype and morphology. Once injected into the adult brain, these cells survive and differentiate into neurons, thus showing that their neuronal differentiation potential is operational also in vivo. In conclusion, our data provide evidence that a specific population of immature cells endowed of neuronal differentiation potential is resident in the leptomeninges throughout the life. As leptomeninges cover the entire central nervous system, these findings could have relevant implications for studies on cortical development and for regenerative medicine applied to neurological disorders. [source] Neurogenesis in a rat model of age-related cognitive declineAGING CELL, Issue 4 2004J. L. Bizon Summary Age-related decrements in hippocampal neurogenesis have been suggested as a basis for learning impairment during aging. In the current study, a rodent model of age-related cognitive decline was used to evaluate neurogenesis in relation to hippocampal function. New hippocampal cell survival was assessed approximately 1 month after a series of intraperitoneal injections of 5-bromo-2,-deoxyuridine (BrdU). Correlational analyses between individual measures of BrdU-positive cells and performance on the Morris water maze task provided no indication that this measure of neurogenesis was more preserved in aged rats with intact cognitive abilities. On the contrary, among aged rats, higher numbers of BrdU-positive cells in the granule cell layer were associated with a greater degree of impairment on the learning task. Double-labelling studies confirmed that the majority of the BrdU+ cells were of the neuronal phenotype; the proportion of differentiated neurons was not different across a broad range of cognitive abilities. These data demonstrate that aged rats that maintain cognitive function do so despite pronounced reductions in hippocampal neurogenesis. In addition, these findings suggest the interesting possibility that impaired hippocampal function is associated with greater survival of newly generated hippocampal neurons at advanced ages. [source] The more you have, the less you get: the functional role of inflammation on neuronal differentiation of endogenous and transplanted neural stem cells in the adult brainJOURNAL OF NEUROCHEMISTRY, Issue 6 2010Patricia Mathieu J. Neurochem. (2010) 112, 1368,1385. Abstract The differentiation of neural stem cells toward a neuronal phenotype is determined by the extracellular and intracellular factors that form the neurogenic niche. In this review, we discuss the available data on the functional role of inflammation and in particular, pro- and anti-inflammatory cytokines, on neuronal differentiation from endogenous and transplanted neural stem/progenitor cells. In addition, we discuss the role of microglial cell activation on these processes and the fact that microglial cell activation is not univocally associated with a pro-inflammatory milieu. We conclude that brain cytokines could be regarded as part of the endogenous neurogenic niche. In addition, we propose that accumulating evidence suggests that pro-inflammatory cytokines have a negative effect on neuronal differentiation, while anti-inflammatory cytokines exert an opposite effect. The clarification of the functional role of cytokines on neuronal differentiation will be relevant not only to better understand adult neurogenesis, but also to envisage complementary treatments to modulate cytokine action that could increase the therapeutic benefit of future progenitor/stem cell-based therapies. [source] Steroid-induced sexual differentiation of the developing brain: multiple pathways, one goalJOURNAL OF NEUROCHEMISTRY, Issue 5 2008Jaclyn M. Schwarz Abstract Hormone exposure, including testosterone and its metabolite estradiol, induces a myriad of effects during a critical period of brain development that are necessary for brain sexual differentiation. Nuclear volume, neuronal morphology, and astrocyte complexity are examples of the wide range of effects by which testosterone and estradiol can induce permanent changes in the function of neurons for the purpose of reproduction in adulthood. This review will examine the multitude of mechanisms by which steroid hormones induce these permanent changes in brain structure and function. Elucidating how steroids alter brain development sheds light on how individual variation in neuronal phenotype is established during a critical period. [source] Rho-associated kinase (ROCK) inhibitor, Y27632, promotes neurite outgrowth in PC12 cells in the absence of NGFJOURNAL OF NEUROCHEMISTRY, Issue 2002R. Nath Neurite extension and retraction are very important processes in the formation of neuronal networks. A strategy for fostering axonal regrowth/regeneration of injured adult neurons is attractive therapeutically for various diseases such as traumatic brain injury, stroke and Alzheimer's disease. The Rho family of small GTPases, including Rac and Cdc42 have been shown to be involved in promoting neurite outgrowth. On the other hand, activation of RhoA induces collapse of growth cone and retraction of neurites. Rho-associated kinase (ROCK) an effector molecule of RhoA, is downstream of a number of axonal outgrowth and growth cone collapse inhibition mechanisms. In the present study, we sought to identify the role of ROCK in neurite outgrowth in PC12 cells. Y27632, a specific inhibitor of ROCK, induced a robust increase in neurite outgrowth in these cells within 24,48 h as visualized by phase contrast microscopy. Staining with FITC-tubulin or phalloidin show extended neurites in PC12 cells treated with Y27632, comparable to that with 100 ng/mL of NGF. Assessment of other biochemical markers of neurite outgrowth such as GAP43, neurofilament and tyrosine hydroxylase phosphorylation further indicates that inhibition of ROCK in PC12 cells causes differentiation of these cells to a neuronal phenotype. [source] Nerve Growth Factor-Induced Differentiation Does Not Alter the Biochemical Properties of a Mutant Prion Protein Expressed in PC12 CellsJOURNAL OF NEUROCHEMISTRY, Issue 1 2000Roberto Chiesa Abstract : Insertional and point mutations in the gene encoding the prion protein (PrP) are responsible for familial prion diseases. We have previously generated lines of Chinese hamster ovary cells that express PrP molecules carrying pathogenic mutations, and found that the mutant proteins display several biochemical properties reminiscent of PrPSc, the infectious isoform of PrP. To analyze the properties and effects of mutant PrP molecules expressed in cells with a neuronal phenotype, we have constructed stably transfected lines of PC12 cells that synthesize a PrP molecule carrying a nine-octapeptide insertion. We report here that this mutant PrP acquires scrapie-like properties, including detergent insolubility, protease resistance, and resistance to phospholipase cleavage of its glycolipid anchor. A detergent-insoluble and phospholipase-resistant form of the mutant protein is also released spontaneously into conditioned medium. These scrapie-like biochemical properties are quantitatively similar to those seen in Chinese hamster ovary cells and are not affected by differentiation of the PC12 cells into sympathetic neurons by nerve growth factor. Moreover, there is no detectable effect of mutant PrP expression on the morphology or viability of the cells in either the differentiated or undifferentiated state. These results indicate that conversion of mutant PrP into a PrPSc -like form does not depend critically on the cellular context, and they suggest that mutant PrP expressed in cultured cells, even those having the phenotype of differentiated neurons, is not neurotoxic. [source] Intracerebral transplantation of neural stem cells combined with trehalose ingestion alleviates pathology in a mouse model of Huntington's diseaseJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2009Chia-Ron Yang Abstract The present investigation examined the neuroprotective benefits for combined trehalose administration with C17.2 neural stem cell transplantation in a transgenic mouse model of Huntington's disease (HD), R6/2. C17.2 neural stem cells have the potential of differentiating into a neuronal phenotype in vitro and have been shown to be effective in the treatment of a variety of lysosomal lipid storage disorders in the nervous system. In this study, we transplanted these cells into the lateral ventricle of R6/2 transgenic mice in order to examine the efficacy of using these cells for correcting the accumulated polyglutamine storage materials in HD. To improve efficacy, animals were fed with a diet rich in trehalose, which has been shown to be beneficial to retard aggregate formation. The combined treatment strategy not only decreased ubiquitin-positive aggregation in striatum, alleviated polyglutamine aggregation formation, and reduced striatal volume, but also extended life span in the R6/2 animal model. Behavioral evaluation showed that the combination treatment improved motor function. Statistical analysis revealed that the combination treatment was more effective than treatment with trehalose alone on the basis of the above biochemical and behavioral criteria. This study provides a strong a basis for further developing an effective therapeutic strategy for HD. © 2008 Wiley-Liss, Inc. [source] Hippocampal adult neurogenesis is enhanced by chronic eszopiclone treatment in ratsJOURNAL OF SLEEP RESEARCH, Issue 3 2010MELVI METHIPPARA Summary The adult hippocampal dentate gyrus (DG) exhibits cell proliferation and neurogenesis throughout life. We examined the effects of daily administration of eszopiclone (Esz), a commonly used hypnotic drug and ,-aminobutyric acid (GABA) agonist, compared with vehicle, on DG cell proliferation and neurogenesis, and on sleep,wake patterns. Esz was administered during the usual sleep period of rats, to mimic typical use in humans. Esz treatment for 7 days did not affect the rate of cell proliferation, as measured by 5-bromo-2,-deoxyuridine (BrdU) immunostaining. However, twice-daily Esz administration for 2 weeks increased survival of newborn cells by 46%. Most surviving cells exhibited a neuronal phenotype, identified as BrdU,neuronal nuclei (NeuN) double-labeling. NeuN is a marker of neurons. Non-rapid eye movement sleep was increased on day 1, but not on days 7 or 14 of Esz administration. Delta electroencephalogram activity was increased on days 1 and 7 of treatment, but not on day 14. There is evidence that enhancement of DG neurogenesis is a critical component of the effects of antidepressant treatments of major depressive disorder (MDD). Adult-born DG cells are responsive to GABAergic stimulation, which promotes cell maturation. The present study suggests that Esz, presumably acting as a GABA agonist, has pro-neurogenic effects in the adult DG. This result is consistent with evidence that Esz enhances the antidepressant treatment response of patients with MDD with insomnia. [source] Temporal and spatial regulation of ,6 integrin expression during the development of the cochlear-vestibular ganglionTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2007Dawn Davies Abstract The neurons of the cochlear-vestibular ganglion (CVG) that innervate the sensory hair cells of the inner ear are derived from the otic epithelium early in development. Neuroblasts detach from neighboring cells, migrate into the mesenchyme where they coalesce to form the ganglion complex, then send processes back into the epithelium. Cell migration and neuronal process formation involve changes in cellular interactions with other cells and proteins in the extracellular matrix that are orchestrated by cell surface-expressed adhesion molecules, including the integrins. I studied the expression pattern of the ,6 integrin subunit during the early development of the CVG using immunohistochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR) in murine tissue sections, otocyst, and ganglion explants. At embryonic day (E)10.5 ,6 integrin was expressed in the otic epithelium but not in migrating neuroblasts. Importantly, the loss of ,6 was associated with exit from the epithelium, not neuronal determination, revealing differentiation cues acutely associated with the cellular environment. Markers of glial and neuronal phenotype showed that ,6-expressing cells present in the CVG at this stage were glia of neural crest origin. By E12.5 ,6 expression in the ganglion increased alongside the elaboration of neuronal processes. Immunohistochemistry applied to otocyst cultures in the absence of glia revealed that neuronal processes remained ,6-negative at this developmental stage and confirmed that ,6 was expressed by closely apposed glia. The spatiotemporal modulation of ,6 expression suggests changing roles for this integrin during the early development of inner ear innervation. J. Comp. Neurol. 502:673,682, 2007. © 2007 Wiley-Liss, Inc. [source] EXPRESSION OF P2X PURINOCEPTORS IN PC12 PHAEOCHROMOCYTOMA CELLSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2007Ji-Hu Sun SUMMARY 1The PC12 cell line, which was cloned from a rat adrenal phaeochromocytoma, is a useful model system. It expresses neuronal properties after treatment with nerve growth factor (NGF). The nervous system-specific P2X receptor subtype P2X2 was initially cloned from PC12 cells, but little is known about the expression of other subtypes of P2X receptors in PC12 cells. The aim of the present study was to investigate whether PC12 cells express the other P2X receptors when exposed to NGF. 2Reverse transcription,polymerase chain reaction at the mRNA level and immunocytochemisty at the protein level showed that, among the seven P2X purinoceptor subtypes, only P2X2 was found to be expressed in undifferentiated PC12 phaeochromocytoma cells, but all seven P2X purinoceptor subtypes were expressed in differentiated PC12 cells treated with 50 µg/mL NGF. 3Electrophysiological recordings indicated that ATP (30 µmol/L) but not ,,,-methylene ATP (,,,-meATP; 30 µmol/L) evoked an inward current in undifferentiated PC12 cells, but both ,,,-meATP and ATP evoked inward currents in differentiated PC12 cells. The results indicate that the NGF-induced P2X receptors expressed in PC12 cells are functional channels. 4The present study suggests that the NGF-induced neuronal phenotype of PC12 cells may be a model for the study of P2X heteromeric receptors. [source] The effects of social environment on adult neurogenesis in the female prairie voleDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2002Christie D. Fowler Abstract In the mammalian brain, adult neurogenesis has been found to occur primarily in the subventricular zone (SVZ) and dentate gyrus of the hippocampus (DG) and to be influenced by both exogenous and endogenous factors. In the present study, we examined the effects of male exposure or social isolation on neurogenesis in adult female prairie voles (Microtus ochrogaster). Newly proliferated cells labeled by a cell proliferation marker, 5-bromo-2,-deoxyuridine (BrdU), were found in the SVZ and DG, as well as in other brain areas, such as the amygdala, hypothalamus, neocortex, and caudate/putamen. Two days of male exposure significantly increased the number of BrdU-labeled cells in the amygdala and hypothalamus in comparison to social isolation. Three weeks later, group differences in BrdU labeling generally persisted in the amygdala, whereas in the hypothalamus, the male-exposed animals had more BrdU-labeled cells than did the female-exposed animals. In the SVZ, 2 days of social isolation increased the number of BrdU-labeled cells compared to female exposure, but this difference was no longer present 3 weeks later. We have also found that the vast majority of the BrdU-labeled cells contained a neuronal marker, indicating neuronal phenotypes. Finally, group differences in the number of cells undergoing apoptosis were subtle and did not seem to account for the observed differences in BrdU labeling. Together, our data indicate that social environment affects neuron proliferation in a stimulus- and site-specific manner in adult female prairie voles. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 115,128, 2002 [source] Genetic engineering of mouse embryonic stem cells by Nurr1 enhances differentiation and maturation into dopaminergic neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2002Sangmi Chung Abstract Nurr1 is a transcription factor critical for the development of midbrain dopaminergic (DA) neurons. This study modified mouse embryonic stem (ES) cells to constitutively express Nurr1 under the elongation factor-1, promoter. The Nurr1-expression in ES cells lead to up-regulation of all DA neuronal markers tested, resulting in about a 4- to 5-fold increase in the proportion of DA neurons. In contrast, other neuronal and glial markers were not significantly changed by Nurr1 expression. It was also observed that there was an additional 4-fold increase in the number of DA neurons in Nurr1-expressing clones following treatment with Shh, FGF8 and ascorbic acid. Several lines of evidence suggest that these neurons may represent midbrain DA neuronal phenotypes; firstly, they coexpress midbrain DA markers such as aromatic l -amino acid decarboxylase, calretinin, and dopamine transporter, in addition to tyrosine hydroxylase and secondly, they do not coexpress other neurotransmitters such as GABA or serotonin. Finally, consistent with an increased number of DA neurons, the Nurr1 transduction enhanced the ability of these neurons to produce and release DA in response to membrane depolarization. This study demonstrates an efficient genetic manipulation of ES cells that facilitates differentiation to midbrain DA neurons, and it will serve as a framework of genetic engineering of ES cells by key transcription factor to regulate their cell fate. [source] Stem cell biology of the central nervous systemJOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2002Hideyuki Okano Abstract Neural stem cells (NSCs) are multipotential progenitor cells that have self-renewal activities. A single NSC is capable of generating various kinds of cells within the central nervous system (CNS), including neurons, astrocytes, and oligodendrocytes. Because of these characteristics, there is increasing interest in NSCs and neural progenitor cells from the aspects of both basic developmental biology and therapeutic applications to the damaged brain. This special issue, dedicated to understanding the nature of the NSCs present in the CNS, presents an introduction to several avenues of research that may lead to feasible strategies for manipulating cells in situ to treat the damaged brain. The topics covered by these studies include the extracellular factors and signal transduction cascades involved in the differentiation and maintenance of NSCs, the population dynamics and locations of NSCs in embryonic and adult brains, prospective identification and isolation of NSCs, the induction of NSCs to adopt particular neuronal phenotypes, and their transplantation into the damaged CNS. © 2002 Wiley-Liss, Inc. [source] | |||||||||||||