Pharmacogenetic inhibition of ventral tegmental area (VTA)/substantia nigra compacta (SNc) dopaminergic (DAergic) neurons promoted non-rapid eye movement (NREM) sleep in tyrosine hydroxylase (TH)-Cre mice.

(A, C) Time course changes of NREM and REM sleep and wakefulness after administration of saline or clozapine-N-oxide (CNO) in hM4Di-expressing TH-Cre mice in the VTA (A, n = 8) and SNc (C, n = 8) DAergic neurons. (B, D) Total sleep–wake amounts during 09:00–13:00 hours (B, VTA) or 09:00–12:00 hours (D, SNc) after administration of saline or CNO. (E–H) Number of NREM sleep bouts with different duration (E, G) and average power density of NREM sleep (F, H) in 4 hours (E, F, VTA) or 3 hours (G, H, SNc) after saline or CNO injection in TH-Cre mice. *p < 0.05, **p < 0.01 versus saline by paired t tests. CNO (1.0 mg/kg) was given by intraperitoneal (IP) injection at 09:00 hours. The horizontal open and filled bars on the x-axes indicate the 12-hour light period and the 12-hour dark period, respectively. Underlying data can be found in S1 Data.