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Trophic effect of cholera toxin B subunit in cultured cerebellar granule neurons: Modulation of intracellular calcium by GM1 ganglioside
Author(s) -
Wu G.,
Lu Z.H.,
Nakamura K.,
Spray D.C.,
Ledeen R.W.
Publication year - 1996
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19960501)44:3<243::aid-jnr5>3.0.co;2-g
Subject(s) - cholera toxin , ganglioside , biology , calcium , intracellular , voltage dependent calcium channel , activator (genetics) , receptor , microbiology and biotechnology , chemistry , endocrinology , biochemistry , organic chemistry
Survival of cerebellar granule cells (CGC) in culture was significantly improved in the presence of cholera toxin B subunit (Ctx B), a ligand which binds to GM1 with specificity and high affinity. This trophic effect was linked to elevation of intracellular calcium ([Ca 2+ ] i ), and was additive to that of high K + . Survival was optimized when Ctx B was present for several days during the early culture period. 45 Ca 2+ and cell survival studies indicated the mechanism to involve enhanced influx of Ca 2+ through L‐type voltage‐sensitive channels, since the trophic effect was blocked by antagonists specific for that channel type. Inhibitors of N ‐methyl‐ D ‐aspartate receptor/channels were without effect. During the early stage of culture Ctx B, together with 25 mM K + , caused [Ca 2+ ] i to rise to 0.2–0.7 μM in a higher proportion of cells than 25 mM K + alone. A significant change in the nature of GM1 modulation of Ca 2+ flux occurred after 7 days in culture, at which time Ctx B ceased to elevate and instead reduced [Ca 2+ ] i below the level attained with 25 mM K + . GM1 thus appears to serve as intrinsic inhibitor of one or more L‐type Ca 2+ channels during the first 7 days in vitro, and then as intrinsic activator of (possibly other) L‐type channels after that period. This is the first demonstration of a modulatory role for GM1 ganglioside affecting Ca 2+ homeostasis in cultured neurons of the CNS. © 1996 Wiley‐Liss, Inc.