Activation of NMDA receptors suppresses Kv7 channel activity in corticotropin‐releasing hormone neurons in Amygdala

Abstract

Corticotropin-releasing hormone (CRH)-expressing neurons in the central nucleus of the amygdala (CeA) are critically involved in autonomic response during stress. Glutamate N-methyl-D-aspartate (NMDA) receptors and Kv7 channels regulate the neuronal activity. However, the interaction between NMDA receptors and Kv7 channels remains unclear. CeA-CRH neurons were identified by an AAV virus-mediated expressing enhanced green fluorescent protein (eGFP) driven by the rat CRH promoter. M-currents carried by Kv7 channels were recorded by whole-cell patch-clamp approach in eGFP-tagged CeA-CRH neurons and Kv7 proteins were measured by western-blot. Acute application of NMDA significantly reduced M-currents recorded from CeA-CRH neurons. NMDA-induced suppression of M-currents was eliminated by chelating intracellular Ca2+ or supplying phosphatidylinositol 4,5-bisphosphate (PIP2) intracellularly but not by inhibiting protein kinase C (PKC), calmodulin, or phosphoinositide3-kinase (PI3K). Incubation of brain slices with NMDA decreased Kv7.3 membrane protein levels and M-currents, while the Kv7.2 expression levels was not altered. Treatment brain slice with PKC inhibitor alleviated the decreases in surface Kv7.3 levels and M-currents in CeA-CRH neurons induced by NMDA incubation. PKC inhibitor alone did not alter surface Kv7 levels and M-currents in CeA-CRH neurons. These data suggest that activation of NMDA receptors suppresses Kv7 channel activity through Ca2+-dependent PIP2 signaling in acute phase and PKC-dependent pathway in chronic phase.