Role of capacitative calcium entry on glutamate-induced calcium influx in type-I rat cortical astrocytes

Capacitative calcium entry (CCE) has been described in a variety of cell ty pes. To date, little is known about its role in the CNS, and in particular in the cross-talk between glia and neurons. We have first analyzed the prop erties of CCE of astrocytes in culture, in comparison with that of the rat basophilic leukemia cell line (RBL-2H3), a model where calcium release-acti vated Ca2+ (CRAC) channels have been unambiguously correlated with CCE. We here show that (i) in astrocytes CCE activated by store depletion and Ca2influx induced by glutamate share the same pharmacological profile of CCE i n RBL-2H3 cells and (ii) glutamate-induced Ca2+ influx in astrocytes plays a primary role in glutamate-dependent intracellular Ca2+ concentration ([Ca 2+](i)) oscillations, being these latter reduced in frequency and amplitude by micromolar concentrations of La3+. Finally, we compared the expression of various mammalian transient receptor potential genes (TRP) in astrocytes and RBL-2H3 cells. Despite the similar pharmacological properties of CCE i n these cells, the pattern of TRP expression is very different. The involve ment of CCE and TRPs in glutamate dependent activation of astrocytes is dis cussed.