AbstractThe sensitivity of many ion channels to phosphatidylinositol-4,5-bisphosphate (PIP₂) levels in the cell membrane suggests that PIP₂ fluctuations are important and general signals modulating neuronal excitability. Yet the PIP₂ dynamics of central neurons in their native environment remained largely unexplored. Here, we examined the behavior of PIP₂ concentrations in response to activation of Gq-coupled neurotransmitter receptors in rat CA1 hippocampal neurons in situ in acute brain slices. Confocal microscopy of the PIP₂-selective molecular sensors tubby_CT-GFP and PLCδ1-PH-GFP showed that pharmacological activation of muscarinic acetylcholine (mAChR) or group I metabotropic glutamate (mGluRI) receptors induces transient depletion of PIP₂ in the soma as well as in the dendritic tree. The observed PIP₂ dynamics were receptor-specific, with mAChR activation inducing stronger PIP₂ depletion than mGluRI, whereas agonists of other Gα_q-coupled receptors expressed in CA1 neurons did not induce measureable PIP₂ depletion. Furthermore, the data show for the first time neuronal receptor-induced oscillations of membrane PIP₂ concentrations. Oscillatory behavior indicated that neurons can rapidly restore PIP₂ levels during persistent activation of Gq and PLC. Electrophysiological responses to receptor activation resembled PIP₂ dynamics in terms of time course and receptor specificity. Our findings support a physiological function of PIP₂ in regulating electrical activity.