Article date: August 1999
By: Yutaro Obara, Masami Takahashi, Norimichi Nakahata, Yasushi Ohizumi, in Volume 127, Issue 7, pages 1577-1582
The aim of the present study was to determine the effects of maitotoxin on nerve growth factor production and the Ca2+ influx in clonal rat glioma cells (C6‐BU‐1).
Maitotoxin (1–10 ng ml−1) induced a profound increase in 45Ca2+ influx in an extracellular Ca2+‐dependent manner. However, high KCl had no effect at all. These effects were supported by the results from the analysis of intracellular Ca2+ concentration using fura 2.
The maitotoxin‐induced 45Ca2+ influx was inhibited by inorganic Ca2+ antagonists, such as Mg2+, Mn2+ and Co2+. The inhibitory effect of Co2+ was antagonized by increasing the extracellular Ca2+ concentrations.
Maitotoxin (3 ng ml−1) as well as A‐23187 (1 μM) and dibutyryl cyclic AMP (0.5 mM) caused an acceleration of nerve growth factor (NGF) production in C6‐BU‐1 cells, as determined by NGF enzyme immunoassay.
Reverse transcription polymerase chain reaction (RT–PCR) analysis showed that maitotoxin (10 ng ml−1) enhanced the expression of NGF mRNA, which was abolished by the removal of extracellular Ca2+. A‐23187 also accelerated its expression.
These results suggest that maitotoxin activates a voltage‐insensitive Ca2+ channel and accelerates NGF production mediated through a Ca2+ signalling pathway in C6‐BU‐1 glioma cells.
The aim of the present study was to determine the effects of maitotoxin on nerve growth factor production and the Ca2+ influx in clonal rat glioma cells (C6‐BU‐1).
Maitotoxin (1–10 ng ml−1) induced a profound increase in 45Ca2+ influx in an extracellular Ca2+‐dependent manner. However, high KCl had no effect at all. These effects were supported by the results from the analysis of intracellular Ca2+ concentration using fura 2.
The maitotoxin‐induced 45Ca2+ influx was inhibited by inorganic Ca2+ antagonists, such as Mg2+, Mn2+ and Co2+. The inhibitory effect of Co2+ was antagonized by increasing the extracellular Ca2+ concentrations.
Maitotoxin (3 ng ml−1) as well as A‐23187 (1 μM) and dibutyryl cyclic AMP (0.5 mM) caused an acceleration of nerve growth factor (NGF) production in C6‐BU‐1 cells, as determined by NGF enzyme immunoassay.
Reverse transcription polymerase chain reaction (RT–PCR) analysis showed that maitotoxin (10 ng ml−1) enhanced the expression of NGF mRNA, which was abolished by the removal of extracellular Ca2+. A‐23187 also accelerated its expression.
These results suggest that maitotoxin activates a voltage‐insensitive Ca2+ channel and accelerates NGF production mediated through a Ca2+ signalling pathway in C6‐BU‐1 glioma cells.
British Journal of Pharmacology (1999) 127, 1577–1582; doi:10.1038/sj.bjp.0702706
DOI: 10.1038/sj.bjp.0702706
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