title: Extracellular presence of IL-8 in the astrocyte-rich cultured cerebellar granule cells under acidosis.
abstract: In order to evaluate the functional role of chemotactic cytokines in the regulation of brain function, we examined the effects of acidosis on the production of IL-8 in cultured neurons and/or astrocyte-rich cerebellar granule cells as assessed by the ELISA method. A time-dependent and significant production of IL-8 was detected in the extracellular fluid of astrocyte-rich cultured cells at 2, 3 and 6 hrs after treatment with acidified Krebs-HEPES buffer (pH 6.9), although such production did not appear in the fluid of neuron-rich cells. Additionally, microglia were detected by microscopic examination in both cultured cells under acidotic conditions. Only astrocyte-containing cultured cells produced a marked increase in intracellular IL-8 under acidotic conditions, although this production was much less than that seen in the extracellular fluid at 6 hrs under acidosis. The increase of IL-8 in astrocyte-rich cultures induced by acidosis was potentiated by treatment with glutamate, which enhanced the increase of cytosolic Ca2+ levels under acidosis, and was affected by extracellular Ca2+ conditions, by cyclosporine A, an inhibitor of calcineurin, and by trifluoperazine, an inhibitor of phospholipase A2. Significant inhibition of IL-8 production was detected after 6 hrs of pretreatment with trifluoperazine. Furthermore, the production of IL-8 under acidosis was associated with the appearance of astrocyte damage. These results suggest that Ca2+-dependent IL-8 is produced by astrocytes, but not neuronal cells, under acidosis, and that this production may be related to the process of cell dysfunction resulting from membrane destruction induced by acidosis.
authors.affiliation: Department of Pharmacology, Tokyo Medical College, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: I
authors.initials: I
authors.lastname: Miura
authors.forename: Y
authors.initials: Y
authors.lastname: Ohgami
authors.forename: M
authors.initials: M
authors.lastname: Fujiwara
mesh_terms: D000138:Acidosis / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D016572:Cyclosporine / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018491:Dopamine Agonists / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D016209:Interleukin-8 / Q000378:metabolism*; D051381:Rats; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D018491:Dopamine Agonists; D007166:Immunosuppressive Agents; D016209:Interleukin-8; D014268:Trifluoperazine; D018698:Glutamic Acid; D016572:Cyclosporine; D002118:Calcium