title: Transient Receptor Potential Vanilloid 4-Induced Modulation of Voltage-Gated Sodium Channels in Hippocampal Neurons.
abstract: Transient receptor potential vanilloid 4 (TRPV4) is reported to control the resting membrane potential and increase excitability in many types of cells. Voltage-gated sodium channels (VGSCs) play an important role in initiating action potentials in neurons. However, whether VGSCs can be modulated by the activation of TRPV4 in hippocampal pyramidal neurons remains unknown. In this study, we tested the effect of TRPV4 agonists (GSK1016790A and 4α-PDD) on voltage-gated sodium current (I Na) in hippocampal CA1 pyramidal neurons and the protein levels of α/β-subunit of VGSCs in the hippocampus of mice subjected to intracerebroventricular (icv.) injection of GSK1016790A (GSK-injected mice). Herein, we report that I Na was inhibited by acute application of GSK1016790A or 4α-PDD. In the presence of TRPV4 agonists, the voltage-dependent inactivation curve shifted to the hyperpolarization, whereas the voltage-dependent activation curve remained unchanged. The TRPV4 agonist-induced inhibition of I Na was blocked by the TRPV4 antagonist or tetrodotoxin. Moreover, blocking protein kinase A (PKA) markedly attenuated the GSK1016790A-induced inhibition of I Na, whereas antagonism of protein kinase C or p38 mitogen-activated protein kinase did not change GSK1016790A action. Finally, the protein levels of Nav1.1, Nav1.2, and Nav1.6 in the hippocampus increased in GSK-injected mice, whereas those of Nav1.3 and Navβ1 remained nearly unchanged. We conclude that I Na is inhibited by the acute activation of TRPV4 through PKA signaling pathway in hippocampal pyramidal neurons, but protein expression of α-subunit of VGSCs is increased by sustained TRPV4 activation, which may compensate for the acute inhibition of I Na and provide a possibility for hyper-excitability upon sustained TRPV4 activation.
authors.affiliation: Department of Physiology, Nanjing Medical University, No. 140, Hanzhong Road, Nanjing, 210029, China.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Hong
authors.affiliation: Department of Physiology, Nanjing Medical University, No. 140, Hanzhong Road, Nanjing, 210029, China.
authors.forename: Pinghui
authors.initials: P
authors.lastname: Jie
authors.affiliation: Department of Physiology, Nanjing Medical University, No. 140, Hanzhong Road, Nanjing, 210029, China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Department of Physiology, Nanjing Medical University, No. 140, Hanzhong Road, Nanjing, 210029, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Chen
authors.affiliation: Department of Physiology, Nanjing Medical University, No. 140, Hanzhong Road, Nanjing, 210029, China. chenl@njmu.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Physiology, Nanjing Medical University, No. 140, Hanzhong Road, Nanjing, 210029, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D013449:Sulfonamides / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000819:agonists / Q000502:physiology*; D061566:Voltage-Gated Sodium Channels / Q000502:physiology*
chemical_list: C530602:N-(1-((4-(2-(((2,4-dichlorophenyl)sulfonyl)amino)-3-hydroxypropanoyl)-1-piperazinyl)carbonyl)-3-methylbutyl)-1-benzothiophene-2-carboxamide; D013449:Sulfonamides; D050916:TRPV Cation Channels; C486576:Trpv4 protein, mouse; D061566:Voltage-Gated Sodium Channels; D007930:Leucine
keywords: Intracellular signaling pathway; TTX-sensitive sodium channel; Transient receptor potential vanilloid 4; Voltage-gated sodium channels; α-subunit of sodium channel