Prostaglandin E2 induces glutamate release from subventricular zone astrocytes

It was recently reported that in one of the adult neurogenetic zones, the subventricular zone (SVZ), astrocyte-like cells release glutamate upon intracellular Ca2+ increases. However, the signals that control Ca2+ activity and glutamate release from SVZ astrocytes are not known. Here, we examined whether prostaglandin E2 (PGE2), which induces glutamate release from mature astrocytes, is such a signal. Using the gramicidin-perforated patch-clamp technique, we show that the activity of N-Methyl-D-Aspartate receptor (NMDAR) channel in neuroblasts is a high fidelity sensor of ambient glutamate levels. Using such sensors, we found that application of PGE2 led to increased ambient glutamate levels in the SVZ. In parallel experiments, PGE2 induced an increase in intracellular Ca2+ levels in SVZ cells, in particular astrocyte-like cells, as shown using Ca2+ imaging. Finally, a PGE2 enzyme immunoassay showed that the choroid plexus of the lateral ventricle and to a lesser extent the SVZ (ten-fold less) released PGE2. These findings suggest that PGE2 is a physiological signal for inducing glutamate release from SVZ astrocytes that is important for controlling neuroblast survival and proliferation. This signal may be accentuated following ischemia or injury-induced PGE2 release and may contribute to the injury-associated increased neurogenesis.