title: Disruption of brain MEK-ERK sequential phosphorylation and activation during midazolam-induced hypnosis in mice: Roles of GABAAreceptor, MEK1 inactivation, and phosphatase MKP-3.
abstract: Midazolam is a positive allosteric modulator at GABAAreceptor that induces a short hypnosis and neuroplasticity, in which the sequential phosphorylation of MEK1/2 and ERK1/2 was shown to play a role. This study investigated the parallel activation of p-MEK and p-ERK and regulatory mechanisms induced by midazolam through the stimulation of GABAAreceptors in the mouse brain. During the time course of midazolam (60mg/kg)-induced sleep in mice (lasting for about 2h) p-Ser217/221 MEK1/2 was increased (+146% to +258%) whereas, unexpectedly, p-Tyr204/Thr202 ERK1/2 was found decreased (-16% to -38%), revealing uncoupling of MEK to ERK signals in various brain regions. Midazolam-induced p-MEK1/2 upregulation was prevented by pretreatment (30min) with flumazenil (10mg/kg), indicating the involvement of GABAAreceptors. Also unexpectedly, midazolam-induced p-ERK1/2 downregulation was not prevented by flumazenil (10 or 30mg/kg). Notably, during midazolam-induced sleep the content of inactivated p-Thr286 MEK1, which can dampen ERK1/2 activation, was increased (+33% to +149%) through a mechanism sensitive to flumazenil (10mg/kg). Midazolam also increased MKP-3 (+13% to +73%) content and this upregulation was prevented by flumazenil (10mg/kg); an effect suggesting ERK inactivation because MKP-3 is the phosphatase selective for ERK1/2 dephosphorylation. The results indicate that during midazolam-induced sleep in mice there is an uncoupling of p-MEK (increased) to p-ERK (decreased) signals. p-ERK1/2 downregulation (not involving GABAAreceptors) is the result of increased inactivated MEK1 and phosphatase MKP-3 (both effects involving GABAAreceptors). These findings are relevant for the neurobiology and clinical use of benzodiazepines.
authors.affiliation: Laboratory of Neuropharmacology, IUNICS-IdISPa, University of the Balearic Islands (UIB), Palma de Mallorca, Spain; Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), ISCIII, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Álvaro-Bartolomé
authors.affiliation: Laboratory of Neuropharmacology, IUNICS-IdISPa, University of the Balearic Islands (UIB), Palma de Mallorca, Spain; Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), ISCIII, Madrid, Spain.
authors.forename: Glòria
authors.initials: G
authors.lastname: Salort
authors.affiliation: Laboratory of Neuropharmacology, IUNICS-IdISPa, University of the Balearic Islands (UIB), Palma de Mallorca, Spain; Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), ISCIII, Madrid, Spain. Electronic address: jesus.garcia-sevilla@uib.es.
authors.forename: Jesús A
authors.initials: JA
authors.lastname: García-Sevilla
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D054642:Dual Specificity Phosphatase 6 / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005442:Flumazenil / Q000494:pharmacology; D018757:GABA Modulators / Q000633:toxicity*; D008297:Male; D051379:Mice; D008874:Midazolam / Q000633:toxicity*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D012890:Sleep / Q000187:drug effects*; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D018757:GABA Modulators; D005442:Flumazenil; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D054642:Dual Specificity Phosphatase 6; D008874:Midazolam
keywords: Flumazenil; Hypnosis; MEK-ERK; MKP-3; Midazolam; Mouse brain