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Taurine‐induced neuronal differentiation: the influence of calcium and the ganglioside gm1
Author(s) -
Spoerri P. E.,
Caple C. G.,
Roisen F. J.
Publication year - 1990
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/0736-5748(90)90081-c
Subject(s) - taurine , neurite , ionophore , ganglioside , calcium , extracellular , chemistry , biochemistry , microbiology and biotechnology , endocrinology , medicine , biology , biophysics , in vitro , amino acid , organic chemistry
Taurine‐induced differentiation was examined in the murine neuroblastoma Neuro‐2a cell line in the presence or absence of the monosialoganglioside GM1 and under conditions in which Ca 2+ levels were manipulated. Taurine (4 mM), GM1 (200 μg/ml), or taurine with GM1 were applied to culture media that contained either various concentrations of Ca 2+ or the Ca 2+ ionophore A23187. Taurine or GM1 and taurine with GM1 increased the number of cells emitting neuntes above that found for controls. A significant interaction was found between treatment (taurine, GM1 or taurine+GM1) and the manipulations of Ca 2+ levels, affecting the number of neuntes and producing changes on the neuritic and perikaryal surfaces. Treatment with both taurine and taurine+GM1 and the various concentrations of Ca 2+ resulted in a significant increase in neurite elongation. The Ca 2+ ionophore A23187 in the presence of taurine or taurine+GM1 caused neuntes to grow longer than observed in media containing Ca 2+ , either in a low concentration (about 125 μM) or at 1–2 mM. Taurine‐treated cultures in the presence of extracellular Ca 2+ or A23187 were characterized by surfaces with numerous microvillar, spine‐like projections. This effect was enhanced with GM1 and was less pronounced in the medium containing low levels of Ca 2+ . Transmission electron microscopy of the taurine‐stimulated neurons revealed an excessive number of clear‐core vesicles (40–200 nm in diameter) in perikarya, neuntes and neuritic varicosities and growth cones. In addition, numerous aggregates of intermediate filaments were seen. They were most abundant in the taurine+GM1 treated cultures. The taurine+A23187 cultures also exhibited numerous microtubules within the elongated processes. The different neuritic patterns induced by taurine under conditions in which Ca 2+ levels were manipulated and/or when cells were exposed to exogenous GM1 suggest that taurine's actions depend in part on Ca 2+ flux.