RESUMEN
Sleep is conserved from invertebrates to vertebrates, and is tightly regulated in a homeostatic manner. The molecular and cellular mechanisms that determine the amount of rapid eye movement sleep (REMS) and non-REMS (NREMS) remain unknown. Here we identify two dominant mutations that affect sleep and wakefulness by using an electroencephalogram/electromyogram-based screen of randomly mutagenized mice. A splicing mutation in the Sik3 protein kinase gene causes a profound decrease in total wake time, owing to an increase in inherent sleep need. Sleep deprivation affects phosphorylation of regulatory sites on the kinase, suggesting a role for SIK3 in the homeostatic regulation of sleep amount. Sik3 orthologues also regulate sleep in fruitflies and roundworms. A missense, gain-of-function mutation in the sodium leak channel NALCN reduces the total amount and episode duration of REMS, apparently by increasing the excitability of REMS-inhibiting neurons. Our results substantiate the use of a forward-genetics approach for studying sleep behaviours in mice, and demonstrate the role of SIK3 and NALCN in regulating the amount of NREMS and REMS, respectively.
Asunto(s)
Canales Iónicos/genética , Mutagénesis , Mutación , Proteínas del Tejido Nervioso/genética , Proteínas Serina-Treonina Quinasas/genética , Sueño/genética , Sueño/fisiología , Secuencia de Aminoácidos , Animales , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Secuencia Conservada , Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Electroencefalografía , Electromiografía , Homeostasis/genética , Canales Iónicos/química , Canales Iónicos/metabolismo , Proteínas de la Membrana , Ratones , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/metabolismo , Neuronas/metabolismo , Fosforilación , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/metabolismo , Empalme del ARN/genética , Distribución Aleatoria , Privación de Sueño , Sueño REM/genética , Sueño REM/fisiología , Factores de Tiempo , Vigilia/genética , Vigilia/fisiologíaRESUMEN
A growing body of evidence suggests that dopamine plays a role in sleep-wake regulation, but the dopamine-producing brain areas that control sleep-wake states are unclear. In this study, we chemogenetically activated dopamine neurons in the ventral midbrain of mice to examine the role of these neurons in sleep-wake regulation. We found that activation of dopamine neurons in the ventral tegmental area (VTA), but not in the substantia nigra, strongly induced wakefulness, although both cell populations expressed the neuronal activity marker c-Fos after chemogenetic stimulation. Analysis of the pattern of behavioral states revealed that VTA activation increased the duration of wakefulness and decreased the number of wakefulness episodes, indicating that wakefulness was consolidated by VTA activation. The increased wakefulness evoked by VTA activation was completely abolished by pretreatment with the dopamine D2/D3 receptor antagonist raclopride, but not by the D1 receptor antagonist SCH23390. These findings indicate that the activation of VTA dopamine neurons promotes wakefulness via D2/D3 receptors.