Insulin-like growth factor I potentiates kainate receptors through a phosphatidylinositol 3-kinase dependent pathway

Neurotrophic factors modulate synaptic plasticity through mechanisms that i nclude regulation of membrane ion channels and neurotransmitter receptors. Recently, it was shown that insulin-like growth factor I (IGF-I) induces de pression of AMPA-mediated currents without affecting NMDA-receptor function in neurons. We now report that IGF-I markedly potentiates the kainate-pref erring ionotropic glutamate receptor in young cerebellar granule neurons ex pressing functional kainate-, but not AMPA-mediated currents. Potentiation of kainate responses by IGF-I is blocked by wortmannin, a phosphatidylinosi tol 3-kinase (P13K) inhibitor, indicating a role for this kinase in the eff ect of IGF-I. These results reinforce the notion that modulation of ionotro pic glutamate receptors are involved in the regulatory actions of IGF-I on neuronal plasticity. NeuroReport 12:1293-1296 (C) 2001 Lippincott Williams & Wilkins.