Álvaro-Bartolomé María, Salort Glòria, García-Sevilla Jesús A
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.
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.
Prog Neuropsychopharmacol Biol Psychiatry. 2017 Apr 3;75:84-93. doi: 10.1016/j.pnpbp.2017.01.008. Epub 2017 Jan 19.
Midazolam is a positive allosteric modulator at GABA receptor 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 GABA receptors 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 GABA receptors. 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 GABA receptors) is the result of increased inactivated MEK1 and phosphatase MKP-3 (both effects involving GABA receptors). These findings are relevant for the neurobiology and clinical use of benzodiazepines.
咪达唑仑是γ-氨基丁酸（GABA）受体的正变构调节剂，可诱导短暂催眠和神经可塑性，其中丝裂原活化蛋白激酶激酶1/2（MEK1/2）和细胞外信号调节激酶1/2（ERK1/2）的顺序磷酸化被证明发挥了作用。本研究通过刺激小鼠脑中的GABA受体，研究了咪达唑仑诱导的p-MEK和p-ERK的平行激活及其调节机制。在咪达唑仑（60mg/kg）诱导小鼠睡眠的过程中（持续约2小时），p-Ser217/221 MEK1/2增加（+146%至+258%），而出乎意料的是，p-Tyr204/Thr202 ERK1/2却下降（-16%至-38%），这表明在各个脑区MEK与ERK信号解偶联。氟马西尼（10mg/kg）预处理（30分钟）可阻止咪达唑仑诱导的p-MEK1/2上调，表明GABA受体参与其中。同样出乎意料的是，氟马西尼（10或30mg/kg）并不能阻止咪达唑仑诱导的p-ERK1/2下调。值得注意的是，在咪达唑仑诱导睡眠期间，可抑制ERK1/2激活的失活型p-Thr286 MEK1的含量通过对氟马西尼（10mg/kg）敏感的机制增加（+33%至+149%）。咪达唑仑还增加了双特异性磷酸酶3（MKP-3）的含量（+13%至+73%），这种上调可被氟马西尼（10mg/kg）阻止；这一效应表明ERK失活，因为MKP-3是选择性使ERK1/2去磷酸化的磷酸酶。结果表明，在咪达唑仑诱导小鼠睡眠期间，p-MEK（增加）与p-ERK（减少）信号解偶联。p-ERK1/2下调（不涉及GABA受体）是失活型MEK1和磷酸酶MKP-3增加的结果（这两种效应均涉及GABA受体）。这些发现与苯二氮䓬类药物的神经生物学和临床应用相关。
