Release of taurine in apoptotic cerebellar granule neurons in culture

• Published in: Pflügers Archiv Vol. 439; no. 3; pp. 271 - 277
• Main Authors: Morán, J, Hernández-Pech, X, Merchant-Larios, H, Pasantes-Morales, H
• Format: Journal Article
• Language: English
• Published: Germany 01.01.2000
• Subjects: Animals; Apoptosis - drug effects; Apoptosis - physiology; Caspase 3; Caspases - metabolism; Cell Size - drug effects; Cell Survival - drug effects; Cells, Cultured; Cerebellum - cytology; Cerebellum - enzymology; Cerebellum - metabolism; Chloride Channels - drug effects; Chloride Channels - metabolism; Coloring Agents; Diffusion; Enzyme Precursors - metabolism; gamma-Aminobutyric Acid - metabolism; Glutamic Acid - metabolism; Membrane Potentials - physiology; Neurons - enzymology; Neurons - metabolism; Neurons - ultrastructure; Potassium Chloride - pharmacology; Rats; Sodium - metabolism; Taurine - metabolism; Tetrazolium Salts; Thiazoles
• ISSN: 0031-6768; 1432-2013
• DOI: 10.1007/s004240050940

Cell shrinkage is a distinctive feature of apoptotic death, but the mechanisms leading to cell volume loss are unclear at present. Activation of pathways extruding intracellular osmolytes such as K+, Cl- and organic molecules may be part of these mechanisms. This was examined in the present work measuring the release of taurine, gamma-amino-butyric acid (GABA) and glutamate in cerebellar granule neurons cultured in conditions resulting in apoptotic death after 4-7 days in vitro (DIV). The basal release of [3H]taurine from cells started to increase (38%) after 3 DIV and reached a maximal enhancement (250%) at 5 DIV. The increase in taurine efflux closely followed the occurrence of apoptotic death markers such as caspase induction and chromatin condensation. The efflux of glutamate (traced as D-aspartate) and [3H]GABA also increased but notably less than that of taurine (90% and 75%, respectively) at 5 DIV. Taurine release associated with apoptosis was unaffected by 4,4'-diisothiocyanatostilbene 2,2'-disulphonic acid (DIDS) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), blockers of the diffusive pathway activated during cell volume regulation in hyposmotic conditions. Taurine efflux was increased in Cl(-)-free (replaced by gluconate) and decreased in Na+-free media. Blockers of the energy-dependent glutamate and taurine carriers, dihydrokainate and guanidinoethane sulfonate, respectively, did not affect the release associated with apoptosis. These results implicate taurine in the mechanism of cell shrinkage during apoptosis.