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  • 1
    Electronic Resource
    Electronic Resource
    Nerve Growth Factor and Dexamethasone Modulate Synthesis and Storage of Catecholamines in Cultured Rat Adrenal Medullary Cells: Dependence on Postnatal Age (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 46 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Catecholamine content and in vitro activities of tyrosine hydroxylase (TH) and noradrenaline N-meth-yltransferase (NMT) were measured in cultures of isolated adrenal medullary cells from newborn and young postnatal rats to study the effects of the differentiation factors glucocorticoids and nerve growth factor (NGF). During the 4-day culture period the cellular catechol-amine (CA) content and TH activity remained stable, whereas NMT activity dropped to about half of the initial level. In cells from 2- and 10-day-old rats 10 μM dexamethasone specifically prevented this loss in NMT activity. Furthermore, this glucocorticoid treatment increased, in a dose-dependent manner, the total CA content by 50–100% over control levels without changes in the adrenaline (A) proportion or TH activity. In contrast, NGF did not affect NMT activities at all. In cells from 10-day-old rats 100 ng/ml NGF elevated TH activity and total CA content to about 160% of controls and did not change the proportion of A. This increase in total CA content was linear with the NGF dose and required 〉5 ng/ml NGF. In chromaffin cells from 2-day-old rats 100 ng/ml NGF affected neither TH activity nor the total content, whereas it significantly reduced the proportion of A by about 25%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb12998.x
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  • 2
    Electronic Resource
    Electronic Resource
    6,6-Disubstituted hex-5-enoic acid derivatives as combined thromboxane A2 receptor antagonists and synthetase inhibitors (1994)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 37 (1994), S. 26-39 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00027a004
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  • 3
    Electronic Resource
    Electronic Resource
    Calcium buffering in bursting Helix pacemaker neurons (1993)
    Springer
    Pflügers Archiv 425 (1993), S. 499-505 
    Details
    ISSN: 1432-2013
    Keywords: Helix bursting neurons ; Calcium imaging ; Calcium buffering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bursting pacemaker neurons of the snail Helix pomatia were voltage-clamped and Ca currents in response to depolarizing steps were recorded. Simultaneously, changes in intracellular Ca concentrations were measured using the fluorescent dye fura-2 and a highly sensitive digital camera. Ca influx through voltage-gated channels induced a spatially non-uniform increase in intracellular Ca. The Ca signals decayed with a time constant of about 5 s. By increasing the concentration of the indicator dye, its Ca-buffering capacity was enhanced and Ca transients in response to depolarization were diminished. Thereby, the endogenous Ca buffer capacity could be determined and was calculated to be about 480 buffered ions for every free Ca ion. The buffer capacity did not vary significantly with the amount of Ca influx within the range tested, suggesting that the buffer is not saturated at Ca concentrations of up to 1μM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374877
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  • 4
    Electronic Resource
    Electronic Resource
    Calcium channel types contributing to excitatory and inhibitory synaptic transmission between individual hypothalamic neurons (1996)
    Springer
    Pflügers Archiv 432 (1996), S. 248-257 
    Details
    ISSN: 1432-2013
    Keywords: Key words Hypothalamus ; Calcium channel ; ω-Conotoxin GVIA ; ω-Conotoxin MVIIC ; ω-agatoxin IVA ; Nifedipine ; Synaptic transmission ; Transmitter release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The contribution of L-, N-, P- and Q-type Ca2+ channels to excitatory and inhibitory synaptic transmission and to whole-cell Ba2+ currents through Ca2+ channels (Ba2+ currents) was investigated in rat hypothalamic neurons grown in dissociated cell culture. Excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) were evoked by stimulating individual neurons under whole-cell patch-clamp conditions. The different types of high-voltage-activated (HVA) Ca2+ channels were identified using nifedipine, ω-Conus geographus toxin VIA (ω-CTx GVIA), ω-Agelenopsis aperta toxin IVA (ω-Aga IVA), and ω-Conus magus toxin VIIC (ω-CTx MVIIC). N-, but not P- or Q-type Ca2+ channels contributed to excitatory as well as inhibitory synaptic transmission together with Ca2+ channels resistant to the aforementioned Ca2+ channel blockers (resistant Ca2+ channels). Reduction of postsynaptic current (PSC) amplitudes by N-type Ca2+ channel blockers was significantly stronger for IPSCs than for EPSCs. In most neurons whole-cell Ba2+ currents were carried by L-type Ca2+ channels and by at least two other Ca2+ channel types, one of which is probably of the Q-type and the others are resistant Ca2+ channels. These results indicate a different contribution of the various Ca2+ channel types to excitatory and inhibitory synaptic transmission and to whole-cell currents in these neurons and suggest different functional roles for the distinct Ca2+ channel types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050131
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  • 5
    Electronic Resource
    Electronic Resource
    Survival, morphology, and catecholamine storage of chromaffin cells in serum-free culture: Evidence for a survival and differentiation promoting activity in medium conditioned by purified chromaffin cells (1987)
    Springer
    Neurochemical research 12 (1987), S. 995-1003 
    Details
    ISSN: 1573-6903
    Keywords: Chromaffin cells ; cell culture ; defined media ; neuronotrophic factors ; catecholamines ; neuronal plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adult bovine and young rat chromaffin cells cultured in serum-free medium were examined for their survival and differentiation following exposure to various additives, trophic agents and conditioned media. Adrenal chromaffin cells dissociated from 8 day old rats were maintained by dexamethasone, NGF and CNTF or without any additives in an N1-supplemented medium in similar numbers as in serum-containing medium for up to 6 days. Neuritic growth elicited by NGF or CNTF was enhanced in the absence of serum. Medium conditioned by purified bovine chromaffin cells improved cell survival and caused neurite outgrowth in a dose-dependent manner. The activiti(es) was sensitive to heat and trypsin and not blocked by the addition of anti-NGF antibodies. Bovine chromaffin cell survival was reduced by 30% when cells were maintained for one week in the absence as compared to the presence of serum. Addition of insulin, the N1 supplement, dexamethasone or dbcAMP single or in combinations improved the survival to different extents. A combination of insulin (5 μg/ml) and dexamethasone (5×10−6M) proved to be optimal in this respect. However, these supplements failed to restore the cellular catecholamine, noradrenaline and adrenaline contents to levels seen in the presence of serum. This was also true for a chromaffin cell-conditioned medium, which improved survival without elevating the catecholamine contents. Conditioned medium, however, partly restored a more physiological adrenaline-noradrenaline-ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00970928
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  • 6
    Electronic Resource
    Electronic Resource
    Embryonic rat adrenal glands in organ culture: Effects of dexamethasone, nerve growth factor and its antibodies on pheochromoblast differentiation (1985)
    Springer
    Cell & tissue research 241 (1985), S. 207-217 
    Details
    ISSN: 1432-0878
    Keywords: Pheochromoblasts ; Neural crest ; Differentiation ; Plasticity ; Tissue culture ; Catecholamine determinations ; Nerve growth factor ; Glucocorticoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present study we sought to determine the developmental potentialities and restrictions of adrenal medullary cells (pheochromoblasts) by investigating their morphological and biochemical response to nerve growth factor (NGF), anti-NGF antibodies and dexamethasone (DEX) after explantation into culture at different embryonic stages. With the exception of explants taken at embryonic day 15 (E 15) cultures of embryonic adrenal glands showed neurite outgrowth, which was not influenced by the addition of NGF, anti-NGF antibodies or DEX to the culture medium during the 4-day-culture period. Pheochromoblasts in E 17+4 explants showed spontaneous ultramorphological and biochemical maturation in terms of an increase in the number of catecholamine storage vesicles (CSVs) per μm2 of cytoplasmic area, diameters of the cores of CSVs, percentages of electron-lucent cores of CSVs indicative of increased storage of adrenaline, overall catecholamine (CA) content and relative amount of adrenaline. NGF did not significantly affect this maturational process. Anti-NGF antibodies slightly decreased the proportion of adrenaline. The most pronounced maturation was seen in response to DEX and DEX plus NGF, although a maturational state equivalent to the E 21 stage was not achieved. E 21+4 explants showed neither spontaneous nor drug-induced biochemical maturation. Medullary cells in NGF-treated E 21 explants frequently retained the morphological features of pheochromoblasts. Treatment with anti-NGF antibodies significantly reduced the portion of adrenaline as compared to any other treatment. We conclude that under the culture conditions employed (1) a few pheochromoblasts spontaneously express a neuronal phenotype, (2) differentiation of pheochromoblasts towards chromaffin cells is enhanced by glucocorticoids but not by NGF, and (3) anti-NGF antibodies do not impair spontaneous neuritic growth and morphological maturation of pheochromoblasts, but cause a small reduction in the relative amount of adrenaline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214643
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