Extension Of Neurite-like Processes Research Articles

Neuroprotective effect of bellis perennis and hypericum perforatum on PC12 cells

The rat pheochromocytoma (PC12) cell line is widely applied as a model system to study a variety of neuronal functions. Upon addition of nerve growth factor (NGF), these cells undergo differentiation characterized by an increase in acetylcholinesterase (AChE) activity, and extension of neurite-like processes. Oxidative stress is implicated in the pathogenesis of neurodegenerative disorders and the purpose of this study was to evaluate the effect of Bellis perennis (Be) and Hypericum perforatum (Hy) (6C and 30C) on healthy neuronal cells. Both homeopathic medicines have been studied at three different concentrations of 2 μl/ml, 4 μl/ml and 8 μl/ml for 96 h in PC12 cells differentiated with NGF. The cell viability was tested by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) and NRU (Neutral Red Uptake). To observe the oxidative damage and evaluate the antioxidative status after exposure to homeopathic medicines, the level of thiobarbituric acid reactive species (TBARS), glutathione (GSH) level, activities of glutathione peroxidase (GPx), glutathione reductase (GR), AcetylCholine Esterase (AChE), Na+K+ATPase and Monoamine Oxidase (MAO) were assayed. These results were compared with positive control (90% alcohol). The content of LPO was significantly decreased in drug treated groups as compared to positive control while the level of GSH was significantly increased. The activities of all other enzymes were significantly restored in drug treated groups as compared to positive control. In conclusion, these medicines have preventive role on differentiated PC 12 cells.

Expression and functional characterization of the serine protease inhibitor neuroserpin in endocrine cells.

Serine proteases play essential roles in a wide variety of cellular processes in endocrine cells. There is a growing interest in the roles of serine protease inhibitors, or serpins, as key regulators of their activity. We have cloned two neuroserpin cDNAs from a rat pituitary cDNA library and confirmed tissue plasminogen activator as a potential target for this inhibitor. We show that neuroserpin transcripts are expressed by endocrine cells in the adrenal and pituitary glands and that immunoreactive neuroserpin is stored in densely cored secretory granules in these cells. Overexpression of neuroserpin in an anterior pituitary corticotroph cell line results in the extension of neurite-like processes, suggesting that neuroserpin may play a role in cell communication, cell adhesion, and/or cell migration.

Ultrastructural changes in pancreatic beta cells treated with NGF and dbcAMP.

Nerve growth factor (NGF) induces morphological and physiological changes in cultured pancreatic beta-cells, including the extension of neurite-like processes. This latter effect is potentiated by dibutyryl cAMP (dbcAMP). beta-cells cultured under these conditions maintain their immunoreactivity to insulin and gamma-amino-butyric acid (GABA). NGF, dbcAMP, and high glucose concentrations also increase the expression of the GABA-synthesizing enzyme glutamic acid decarboxylase-65 in cultured beta-cells. The aim of this work was to study the effect of NGF alone or in combination with dbcAMP on pancreatic beta-cell ultrastructural morphology, after 10 days in culture. We used light microscopy, scanning electron microscopy, and transmission electron microscopy to analyze the modifications in cell surface and neurite-like projections. Morphometric analysis showed that NGF and/or dbcAMP treatment substantially increased the insulin and GABA content in granules and rough endoplasmic reticulum. Given that pancreatic beta-cells express NGF receptors and that NGF is synthesized and secreted by beta-cells, these results further suggest that NGF could have trophic actions on pancreatic hormone synthesis and/or storage.

Effects of nerve growth factor and glucocorticoid on cultured human pheochromocytoma cells

Primary cell cultures of two human pheochromocytomas (PC) that were associated with high serum levels of adrenaline and noradrenaline were developed to study the effects of nerve growth factor (NGF) and dexamethasone on the morphology and function of PC cells in vitro. By phase-contrast microscopy, cultured cells were small and hyperchromatic on the first day of culture; neurite-like processes that extended to other cells developed several days later and were maintained for more than 3 months. NGF (100ng/ml), dexamethasone (10−5M), or NGF + dexamethasone were added to the culture media 2 weeks after the cultured cells had stabilized. Catecholamine concentrations in the medium were maintained at higher levels after addition of NGF, dexamethasone, or NGF + dexamethasone as compared to control cells. In the presence of NGF, extension of neurite-like processes was clearly accelerated, while high levels of dexamethasone inhibited growth of processes. These in vitro studies showed that the addition of NGF or the removal of dexamethasone induces differentiation of adrenal neurons present in pheochromocytomas, suggesting that adrenocortical steroid hormones influence the morphological control of adrenal medullary cells.

Neuron-like phenotypic changes in pancreatic β-cells induced by NGF, FGF, and dbcAMP

We studied the effects of nerve growth factor (NGF), fibroblast growth factor (FGF), and dibutyryl-cAMP (dbcAMP) on rat pancreatic β-cell morphology and of NGF and dbcAMP on insulin secretion. After 2 wk in culture, nearly 3% of β-cells extended neurite-like processes spontaneously; when cells were treated with NGF, almost 30% of them extended processes. In the presence of dbcAMP, almost all β-cells flattened, and the extension of neurite-like processes was more pronounced in fetal than in adult cells. The most prominent effect, regardless of age, was observed in cells treated with NGF and dbcAMP together, since the percentage of neurite-like bearing β-cells increased to 50%. β-cells cultured under these conditions maintained their immunoreactivity to insulin and nearly all β-cells and their neurite-like processes were also positive to GABA, tubulin, tau protein, and N-CAM. FGF increased the percentage of adult β-cells bearing neurite-like processes to 13%, and FGF and dbcAMP applied together to 40%. β-cells treated with NGF and dbcAMP for 5 to 7 d preserved their capability to secrete the hormone in response to different extracellular glucose concentrations. Insulin secretion of dbcAMP-treated β-cells was 2.5-fold higher than in control cells. NGF-treated cells were able to discriminate between different glucose concentrations, a property lost in control cells with time in culture.

Characteristics of 45Ca uptake stimulated by high KCl of differentiated and undifferentiated NG108-15 and PC12h cells.

The characteristics of KCl-stimulated 45Ca uptake by neuroblastoma X glioma hybrid NG108-15 cells induced to differentiate with dibutyryl cAMP (Bt2cAMP) and of PC12h pheochromocytoma cells induced to differentiate with nerve growth factor (NGF) were studied. The extent and rate of KCl-stimulated 45Ca uptake by differentiated NG108-15 cells induced with Bt2cAMP were significantly higher than those of the undifferentiated cells. However, differentiation of PC12h cells induced with NGF did not enhance their extent or rate of KCl-stimulated 45Ca uptake. The effects of Ca agonist and antagonists indicated that the characteristics of KCl-stimulated 45Ca uptake by Bt2cAMP-treated NG108-15 cells and NGF-treated PC12h cells mainly reflected those of peripheral L-type voltage-sensitive calcium channels activated by high KCl. These results suggest that differentiated neural cells did not all show an enhanced capacity for KCl-stimulated 45Ca uptake, although the characteristic patterns of differentiation (extension of neurite-like processes, etc.) and that of effect by Ca agonist or antagonists on NG108-15 cells and PC12h cells were similar.