Figure 5.

Excessive GABA leads to suppression of neuronal activity. A, Quantification of paralyzed flies on exposure to 30°C. Ectopic activation of GABAergic neurons via GAD1-Gal4-induced expression of TrpA1 leads to acute suppression of neuronal activity and paralysis. B, Distinct impact of cortex glia and astrocyte Ca²⁺ signals on neuronal activity. Ca²⁺ influx in cortex glia leads to increased neural activity and seizure-like behavior, whereas enhanced astrocyte Ca²⁺ signal causes suppression of neuronal activity and paralysis. Together, they constitute a Ca²⁺-dependent glial mechanism to fine-tune neuronal function. C-C”, Model of how astrocyte Ca²⁺ signaling regulates neuronal activity. Astrocyte Ca²⁺ influx leads to acute endocytosis of membrane GAT, reduced GABA uptake, and suppression of neuronal activity. Inhibition of Rab11 function reduces the removal of membrane GAT and sustains GABA uptake, hence ameliorating the paralysis caused by astrocyte Ca²⁺ influx.