ISSN:
1471-4159
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Medizin
Notizen:
Abstract: The release of excitatory amino acids (EAAs) from neuron-free cultures of neocortical astrocytes was monitored using HPLC. The neuroligand bradykinin caused a dose-dependent receptor-mediated increase in release of the EAAs glutamate and aspartate from type 1 astrocyte cell cultures obtained from rat cerebral cortex. Removal of calcium from the extracellular fluid prevented the bradykinin-induced release of EAAs from astrocytes. The addition of the calcium ionophore ionomycin caused a calcium-dependent release of EAAs. Inhibitors of the glutamate transporters p-chloromercuriphenylsulfonic acid, l-trans-pyrrolidine-2,4-dicarboxylate, and dihydrokainate failed to impair the ability of bradykinin to stimulate glutamate release from astrocytes. α-Latrotoxin, an active compound of black widow spider venom, caused a significant increase of the release of glutamate in calcium-containing saline. In calcium-depleted saline, α-latrotoxin produced an initial increase in the concentration of glutamate followed by a decline in the concentration of glutamate indicating stimulation of exocytosis coupled with low calcium-induced inhibition of endocytosis. Taken together, these data suggest that astrocytes may release neurotransmitter through a mechanism that is similar to the neuronal secretory process. Given the important role of glutamate in the induction of long-term potentiation, learning, memory, and excitotoxicity, it will be important to determine external signals that control both the uptake and release of glutamate by astrocytes.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1046/j.1471-4159.1996.66020676.x
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