Sleep/wakefulness state change is regulated by neurons, however, its regulatory mechanism is still unclear. Here we found that GABAergic neurons in the ventral tegmental area (VTA) have an important role in the regulation of sleep/wakefulness. Adeno-associate virus (AAV) vectors were injected into VTA of glutamic acid decarboxylase (GAD)-Cre mice in which GABAergic neurons are exclusively express Cre. To manipulate GABAergic neurons in the VTA, channelrhodopsin2 (ChR2), anion-channelrhodopsin2 (ACR2) or hM3Dq was expressed by AAV. Chemogenetical activation of these neurons significantly increased time in NREM sleep. To reveal neural mechanism, slice patch clamp was performed. AAV was injected to VTA to express ChR2 in the GABAergic neurons in the VTA. Orexin neurons expressing fluorescent protein were identified and recorded. Then, GABAergic nerve terminals from VTA were stimulated by blue light. Blue light significantly inhibited activity of orexin neurons. On the other hand, optogenetical inhibition of these neurons using ACR2 immediately induced wakefulness. To evaluate physiological importance of this response, these neurons were inhibited during recovery sleep after sleep deprivation for 4 hr. Inhibition of GABAergic neurons induced wakefulness even in the very sleepy condition. These results suggest that activity of GABAergic neurons in the VTA is critical to change sleep/wakefulness state especially in the regulation of NREM sleep and wakefulness.

To: 要旨(抄録)