| OCR Text |
Show 80 limited approaches to monitoring intracellular astrocyte dynamics. In this report, we described acute changes in intrinsic calcium dynamics in reactive astrocytes, obtained from adult animals, which were detected with novel tools for observing calcium activity with high spatiotemporal resolution (Gee et al., 2014). Several groups have reported changes in astrocytic calcium activity following exposure to LPS. However, there were several major technology-related drawbacks to these studies. They were performed in cultured astrocytes, which in many ways do not represent astrocytes in situ. Cultured astrocytes are most often derived from the immature brain which differs from the mature brain in many ways (Sun et al., 2013). Bulk loaded synthetic dyes, which do not diffuse throughout the whole cytosolic compartment, were also used in previous studies. Therefore, the experiments reported in the past were performed in somas and large processes. In contrast, we administered LPS in vivo and subsequently recorded astrocytic calcium dynamics in acute brain slices (i.e., in situ) using GCaMP5G. Thus, we were able to readily observe calcium dynamics throughout the whole cytosolic compartment including in astrocytic fine processes. Our results obtained from somatic recordings are consistent with a previous report which demonstrated that calcium-dependent basal fluorescence acutely decreases in LPS-exposed cultured astrocytes (Strokin et al., 2011). Furthermore, we showed that intrinsic event frequency in astrocytic processes decreases following LPS-exposure, but lags behind the somatic decrease. The distinct temporal-dependent progression of changes in somatic and process activity could result from compartment-specific calcium source dependences and composition of calcium-dependent pathways. Differential expression of glutamatergic and purinergic responses has been described previously (Tang et al., 2015). We have not determined the calcium contributions to intrinsic events but they are likely to derive from |
