TY - JOUR
T1 - Trophic effect of cholera toxin B subunit in cultured cerebellar granule neurons
T2 - Modulation of intracellular calcium by GM1 ganglioside
AU - Wu, G.
AU - Lu, Z. H.
AU - Nakamura, K.
AU - Spray, D. C.
AU - Ledeen, R. W.
PY - 1996
Y1 - 1996
N2 - 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. 45Ca 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.
AB - 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. 45Ca 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.
KW - L-type calcium channel
KW - calcium modulation
KW - cerebellar granule neurons
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U2 - 10.1002/(SICI)1097-4547(19960501)44:3<243::AID-JNR5>3.0.CO;2-G
DO - 10.1002/(SICI)1097-4547(19960501)44:3<243::AID-JNR5>3.0.CO;2-G
M3 - Article
C2 - 8723763
AN - SCOPUS:0029913460
SN - 0360-4012
VL - 44
SP - 243
EP - 254
JO - Journal of Neuroscience Research
JF - Journal of Neuroscience Research
IS - 3
ER -