title: Riluzole inhibits spontaneous Ca2+ signaling in neuroendocrine cells by activation of K+ channels and inhibition of Na+ channels.
abstract: The neuroprotective drug riluzole has multiple effects on cellular signaling. We found that riluzole rapidly and reversibly inhibited spontaneous Ca2+ oscillations in both immortalized GnRH-secreting hypothalamic neurons (GT1 cells) and in the prolactin and growth-hormone-secreting GH3 cell line. At lower concentrations (100 nm-5 microM), riluzole reduced the amplitude and frequency of spontaneous Ca2+ oscillations, whereas at higher concentrations it abolished spontaneous Ca2+ signaling. Whole-cell current clamp recordings in GH3 cells revealed that riluzole decreased the action potential frequency, amplitude, and duration. Riluzole inhibited voltage-gated Na+ currents, increased iberiotoxin-sensitive voltage-gated K+ currents, and had no effect on voltage-gated Ca2+ currents in GH3 cells. Riluzole also inhibited voltage-gated Na+ currents and increased voltage-gated K+ channels in GT1 cells. The inhibitory effects of riluzole on Ca2+ signaling were blocked by pretreatment with iberiotoxin in GH3 cells, but only partially reduced by iberiotoxin in GT1 cells. These results indicate that riluzole inhibits Ca2+ signaling primarily by activation of K+ channels in GH3 cells, and also by inhibition of Na+ channels in GT1 cells. Riluzole's inhibition of spontaneous excitability and Ca2+ signaling may be involved in its multiple effects on cellular function in the nervous system.
authors.affiliation: Department of Neurology, UCLA School of Medicine, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Beltran-Parrazal
authors.forename: Andrew
authors.initials: A
authors.lastname: Charles
mesh_terms: D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D009490:Neurosecretory Systems / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D019782:Riluzole / Q000494:pharmacology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000378:metabolism*
chemical_list: D015221:Potassium Channels; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D019782:Riluzole