Properties Of Neuronal Cells Research Articles

IGF1R expression by adult oligodendrocytes is not required in the steady-state but supports neuroinflammation.

In the central nervous system (CNS), insulin-like growth factor 1 (IGF-1) regulates myelination by oligodendrocyte (ODC) precursor cells and shows anti-apoptotic properties in neuronal cells in different in vitro and in vivo systems. Previous work also suggests that IGF-1 protects ODCs from cell death and enhances remyelination in models of toxin-induced and autoimmune demyelination. However, since evidence remains controversial, the therapeutic potential of IGF-1 in demyelinating CNS conditions is unclear. To finally shed light on the function of IGF1-signaling for ODCs, we deleted insulin-like growth factor 1 receptor (IGF1R) specifically in mature ODCs of the mouse. We found that ODC survival and myelin status were unaffected by the absence of IGF1R until 15 months of age, indicating that IGF-1 signaling does not play a major role in post-mitotic ODCs during homeostasis. Notably, the absence of IGF1R did neither affect ODC survival nor myelin status upon cuprizone intoxication or induction of experimental autoimmune encephalomyelitis (EAE), models for toxic and autoimmune demyelination, respectively. Surprisingly, however, the absence of IGF1R from ODCs protected against clinical neuroinflammation in the EAE model. Together, our data indicate that IGF-1 signaling is not required for the function and survival of mature ODCs in steady-state and disease.

The effects of NP-POL, the nonapeptide constituent of Colostrinin, on intracellular antioxidant system

Introduction: Latest findings show that the proline-rich polypeptide complex (PRP), known as Colostrinin, and its component peptides may have beneficial effects on cellular response to oxidative stress, which is the main aspect of aging and an essential feature in neurodegenerative disorders. Recently isolated and described nonapeptide NP-POL (RPKHPIKHQ) was shown to have potential protective properties in neuronal cells, including the regulation of cell survival, neurite protection and intracellular ROS release. Based on those findings, further studies were performed covering the possible effects of NP-POL on molecular and enzymatic mechanisms of response to oxidative stress. Materials/Methods: To evaluate the regulatory effects of NP-POL on oxidative stress, 6-hydroxydopamine-treated rat pheochromocytoma (PC12) cells were used as an experimental model and a series of assays were performed, including H2O2 release, glutathione turnover and the expression and activity of superoxide dismutases (Mn-SOD and Cu-Zn-SOD). Results: NP-POL was shown to modify the cellular antioxidative response to reverse the toxic effects of 6-hydroxydopamine. The direct effects of NP-POL include a significant reduction of the total amount of released H2O2 and enhanced glutathione activation. Moreover, NP-POL enhanced the expression of superoxide dismutase in untreated cells, which confirms its contribution in secondary enzymatic response. Discussion: The newly discovered peptide NP-POL, isolated from the colostrum-derived polypeptide complex Colostrinin, was shown to have potential antioxidant and neuroprotective properties, which makes it very promising as a natural therapeutic in neurodegenerative diseases.

H2O2 attenuates IGF-1R tyrosine phosphorylation and its survival signaling properties in neuronal cells via NR2B containing NMDA receptor.

Impairment of insulin-like growth factor I (IGF-I) signaling plays an important role in the development of neurodegeneration. In the present study, we investigated the effect of H2O2 on the survival signaling of IGF-1 and its underlying mechanisms in human neuronal cells SH-SY5Y. Our results showed that IGF-1 promoted cell survival and stimulated phosphorylation of IGF-1R as well as its downstream targets like AKT and ERK1/2 in these cells. Meanwhile, these effects of IGF-1 were abolished by H2O2 at 200μM concentration which did not cause any significant toxicity to cells itself in our experiments. Moreover, studies using various glutamate receptor subtype antagonists displayed that N-methyl-D -aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) blocked the effects of H2O2, whereas other glutamate receptor subtype antagonists, such as non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), metabolic glutamate receptor antagonists LY341495 and CPCCOEt, had no effect. Further studies revealed that NR2B-containing NMDARs are responsible for these effects as its effects were blocked by pharmacological inhibitor Ro25-698 or specific siRNA for NR2B, but not NR2A. Finally, our data also showed that Ca2+ influx contributes to the effects of H2O2. Similar results were obtained in primary cultured cortical neurons. Taken together, the results from the present study suggested that H2O2 attenuated IGF-1R tyrosine phosphorylation and its survival signaling properties via NR2B containing NMDA receptors and Ca2+ influx in SH-SY5Y cells. Therefore, NMDAR antagonists, especially NR2B-selective ones, combined with IGF-1 may serve as an alternative therapeutic agent for oxidative stress related neurodegenerative disease.

Design of Experimental Hypoxia Chamber for Cell Culture with Manipulatable Microprobe

Hypoxia chambers are a well developed device for investigating the biochemical effect of tissue under hypoxic conditions. The enclosed design of the chamber is essential to prevent re-oxygenation by external air but also limits access to measurements during experiments, resulting in fewer sampling points or only pre- and post-hypoxia data. The present study implements a non-enclosed hypoxia chamber to provide free entry for manipulating microprobes, which makes frequent sampling during experiments feasible. A steady deoxygenated environment is created directly by supplying nitrogen to the culture medium or indirectly by supplying a pre-prepared deoxygenated medium. Three hypoxia chamber schemes were designed and validated to induce a low oxygen level. In addition, nerve growth factor (NGF)-differentiated PC12 cells were utilized to verify the efficiency of ischemic conditions. Results indicate that the design with a continuous supply of nitrogen into the water-trapped chamber provides the most stable deoxygenated environment and prevents the dehydration effect caused by nitrogen pumping. The designed hypoxia chamber can be used for continuous monitoring of optical or electrical properties of neuronal cells insulted by ischemia for drug screening or fundamental research.

Neuroprotective Effects of a Novel Peptide Purified from Venison Protein

A novel antioxidative peptide (APVPH I, antioxidative peptides from venison protein hydrolysates I) was purified from venison by enzymatic hydrolysis, column chromatography of DEAE-Sephacel and high performance liquid chromatography. The molecular weight of the purified peptide was found to be 9,853 Da and the amino acid sequences of the purified peptide was Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly. The purpose of this study was to evaluate the effects of APVPH I against H2O2-induced neuronal cells damage in PC-12 cells. Antioxidative enzyme levels in cultured neuronal cells were increased in the presence of the peptide. In addition, APVPH I inhibited productions of nitric oxide (NO), reactive oxygen species (ROS), malondialdehyde (MDA) and cell death against H2O2-induced neuronal cells damage in PC-12 cells. It was presumed to be APVPH I involved in regulating the apoptosis-related gene expression in the cell environment. Present results indicate APVPH I substantially contribute to antioxidative properties in neuronal cells.

Granulocyte colony-stimulating factor for recalcitrant postherpetic neuralgia: a prospective, open, pilot study in three patients

Summary Recent experimental studies have shown that granulocyte colony-stimulating factor (G-CSF) has neuroprotective and regenerative properties in neuronal cells, suggesting its use as a potential treatment for recalcitrant postherpetic neuralgia (PHN). We evaluated the efficacy and safety of G-CSF in patients with recalcitrant PHN. Three patients with recalcitrant PHN were treated with subcutaneous injection of recombinant human G-CSF 10 μg/kg once daily for 5 days. Assessments were performed at baseline and at weeks 1, 4, 8, 12 and 48 using the Brief Pain Inventory (BPI) and the Clinician Global Impression (CGI) score. All patients found improvement in BPI and CGI scores throughout the study. We suggest that G-CSF may help alleviate neuropathic pain and improve the overall quality of life in patients with PHN.

Melatonin increases cell proliferation in the dentate gyrus of maternally separated rats.

Melatonin in mammals, produced by the pineal gland and elsewhere, has shown antioxidant and neuroprotective properties in neuronal cells. We investigated whether melatonin would increase newly born cells (cell proliferation) in the dentate gyrus of maternally separated rats. To examine the effect of melatonin on cell proliferation of the dentate gyrus in maternally separated rats, 5-bromo-2'-deoxyuridine (BrdU) immunohistochemistry was performed. Rat pups were separated from their mothers and socially isolated on postnatal day 14. Melatonin (10 mg/kg, i.p.) and BrdU (50 mg/kg, i.p.) were given to them for 7 days. The number of BrdU-positive cells was significantly increased in the dentate gyrus of maternally separated pups with melatonin administration (P < 0.001). In addition, the expression of glucocorticoid receptor was significantly decreased in the dentate gyrus compared with maternally separated pups not given melatonin (P < 0.001). This is the first report that melatonin increases cell proliferation in the dentate gyrus of maternally separated rats.

Calbindin-D28k Is Expressed in Osteoblastic Cells and Suppresses Their Apoptosis by Inhibiting Caspase-3 Activity

The rate of osteoblast apoptosis is a critical determinant of the rate of bone formation. Because the calcium-binding protein calbindin-D(28k) has anti-apoptotic properties in neuronal cells and lymphocytes, we searched for the presence of this protein in osteoblastic cells and investigated whether it can modify their response to proapoptotic signals. Calbindin-D(28K) was expressed at low levels in several osteoblastic cell lines and at high levels in primary cultures of murine osteoblastic cells. Transient transfection of rat calbindin-D(28k) cDNA blocked tumor necrosis factor alpha (TNFalpha)-induced apoptosis in osteoblastic MC3T3-E1 cells, as determined by cell viability and nuclear morphology of cells cotransfected with the green fluorescent protein targeted to the nucleus, whereas transfection of the empty vector had no effect. Calbindin-D(28k) levels in several stably transfected MC3T3-E1 lines were directly related to protection from TNFalpha-induced apoptosis. Purified rat calbindin-D(28k) markedly reduced the activity of caspase-3, a critical molecule for the degradation phase of apoptosis, in a cell-free assay. In addition, cell extracts from MC3T3-E1 cells expressing high levels of calbindin-D(28k) decreased caspase-3 activity, compared with extracts from vector-transfected cells. This effect was apparently unrelated to the calcium binding properties of calbindin, as chelation of calcium by EGTA or addition of other calcium-binding proteins such as calbindin-D(9k), S100, calmodulin, and osteocalcin, did not affect caspase-3 activity. Last, calbindin-D(28k) interacts with the active form of caspase-3 as demonstrated by a GST pull-down assay. These results demonstrate that calbindin-D(28k) is a biosynthetic product of osteoblasts with a role in the regulation of apoptosis. They also reveal that the antiapoptotic properties of calbindin-D(28k) may result not only from calcium buffering but also from the ability of the protein to interact with and to inhibit caspase-3 activity, a property that is independent of its calcium binding capability.

The effects of exposure to exogenous fatty acids and membrane fatty acid modification on the electrical properties of NG108-15 cells

The role of membrane lipid composition in determining the electrical properties of neuronal cells was investigated by altering the available fatty acids in the growth medium of cultured neuroblastoma X glioma hybrid cells, clone NG108-15. Growth of the cells for several days in the presence of polyunsaturated fatty acids (linoleic, linolenic, and arachidonic) caused a pronounced decrease in the Na+ action-potential rate of rise (dV/dt) and smaller decreases in the amplitude, measured by intracellular recording. Oleic acid had no effect on the action potentials generated by the cells. In contrast, a saturated fatty acid (palmitate) and a trans monounsaturated fatty acid (elaidate) caused increases in both the rate of rise and the amplitude. No changes in the resting membrane potentials or Ca2+ action potentials of fatty acid-treated cells were observed. The membrane capacitance and time constant were not altered by exposure to arachidonate, oleate, or elaidate, whereas arachidonate caused a small increase in membrane resistance. Examination of the membrane phospholipid fatty acid composition of cells grown with various fatty acids revealed no consistent alterations which could explain these results. To examine the mechanism for arachidonate-induced decreases in dV/dt, the binding of 3H-saxitoxin (known to interact with voltage-sensitive Na+) channels was measured. Membranes from cells grown with arachidonate contained fewer saxitoxin binding sites, suggesting fewer Na+ channels in these cells. We conclude that conditions which lead to major changes in the membrane fatty acid composition have no effect on the resting membrane potential, membrane capacitance, time constant, or Ca2+ action potentials in NG108-15 cells. Membrane resistance also does not appear to be very sensitive to membrane fatty acid composition. However, changes in the availability of fatty acids and/or changes in the subsequent membrane fatty acid composition lead to altered Na+ action potentials. The primary mechanism for this alteration appears to be through changes in the number of Na+ channels in the cells.

Growth and morphology of neuronal cell lines cultured in perfusion.

To optimize culture conditions and gain a more reliable culturing system for studies of metabolic properties of neuronal cells, a simplified perfusion chamber was developed. It consists of two parts: a perfusion block and a standard plastic culture dish. To confirm the suitability of this chamber for continuous culturing of anchorage-dependent cells, the growth and morphology of the four neuronal cell lines, glioma C6 and glioma 138MG, neuroblastoma C1300, clones N1E115 and N18 were followed for 4 d using both traditional and perfusion techniques. A marked increase in growth and a decrease in the degree of morphological differentiation were obtained with the latter technique compared to the former.