Interleukin-10 modulates [Ca2+]i response induced by repeated NMDA receptor activation with brief hypoxia through inhibition of InsP(3)-sensitive internal stores in hippocampal neurons.

The goal of this study was to evaluate an effect of interleukin-10 (IL-10) on the Ca(2+) response induced by repeated NMDA receptor activation with brief hypoxia in cultured hippocampal neurons. We focused on the importance of internal Ca(2+) stores in the modulation of this Ca(2+) response by IL-10. To test this, we compared roles of InsP(3)- and ryanodine-sensitive internal stores in the effects of IL-10. Measurements of intracellular cytosolic calcium concentration (Ca(2+)) in cultured hippocampal neurons were made by imaging Fura-2AM loaded hippocampal cells. Repeated episodes of NMDA receptor activation with brief hypoxia induced the spontaneous (s) Ca(2+) increases about 3 min after each hypoxic episode. The amplitude of the sCa(2+) increases was progressively enhanced from the first hypoxic episode to the third one. IL-10 (1 ng/ml) abolished these sCa(2+) increases. Exposure of cultured hippocampal neurons with thapsigargin (1 μM) or an inhibitor of phospholipase C (U73122, 1 μM) for 10 min also abolished the sCa(2+) increases. On the other hand, antagonist of ryanodine receptors (ryanodine, 1 μM) did not affect this Ca(2+) response. These studies appear to provide the first evidence that Ca(2+) release from internal stores is affected by anti-inflammatory cytokine IL-10 in brain neurons. It is suggested that these data increase our understanding of the neuroprotective mechanisms of IL-10 in the early phase of hypoxia.