HB-EGF and zinc activate EGFR to induce reactive neural stem cells in the mouse hippocampus after seizures

Abstract

Hippocampal seizures mimicking mesial temporal lobe epilepsy (MTLE) cause a profound disruption of the adult neurogenic niche in mice. Seizures provoke neural stem cells to switch to a reactive phenotype (reactive-neural stem cells, React-NSCs)) characterized by multibranched hypertrophic morphology, massive activation to enter mitosis, symmetric division and final differentiation into reactive astrocytes. As a result, neurogenesis is chronically impaired. Here we, using a mouse model of MTLE, show that the epidermal growth factor receptor (EGFR) signalization pathway is key for the induction of React-NSCs and that its inhibition exerts a beneficial effect on the neurogenic niche. We show that during the initial days after the induction of seizures by a single intrahippocampal injection of kainic acid, a strong release of zinc and heparin-binding epidermal growth factor, both activators of the EGFR signalization pathway in neural stem cells, is produced. Administration of the EGFR inhibitor gefitinib, a chemotherapeutic in clinical phase IV, prevents the induction of React-NSCs and preserves neurogenesis.