Long-term facilitation of spontaneous calcium oscillations in astrocytes with endogenous adenosine in hippocampal slice cultures

It is well established that astrocytes release gliotransmitters and moderate neuronal activity in the central nervous system via intracellular Ca2+ dynamics. Astrocytic Ca2+ oscillations are one type of spontaneous Ca2+ mobilization that occurs in astrocytes. However, the modulation of spontaneous astrocytic Ca2+ oscillations, especially in pathophysiological conditions, is not yet fully understood. Here, we demonstrate that activation of adenosine receptors induces a long-lasting increase in the frequency of astrocytic Ca2+ oscillations in rat hippocampal slice cultures. The long-term facilitation of the frequency of Ca2+ oscillations was mediated by endogenous adenosine generated via breakdown of extracellular ATP by ecto-ATPase. We also demonstrate that local tissue injury with ultraviolet irradiation can cause this long-term facilitation of Ca2+ oscillations via endogenous adenosine. Our data suggest that endogenous adenosine is one of the modulators of spontaneous astrocytic Ca2+ oscillations in the rat hippocampus, and may play a significant role in altered Ca2+ dynamics in astrocytes observed during pathophysiological conditions.