Fig. 5: Inhibition of CRH release in TRN consolidates NREMS.

a Schematic of the experimental approach for optogenetic inhibition of CRH release. The inhibitory opsin Parapinopsin (PPO) was virally expressed in CRH-IRES-Cre mice that targeted all CRH projections to the sensory TRN. Mice were implanted with bilateral optic fibers above the TRN and electrodes for EEG/EMG recordings. CRH release was selectively photoinhibited during NREMS using 456 nm light stimulation at 10 Hz, triggered every 50 s of closed-loop detected NREMS with a minimum interval of 50 s between stimulations. The depiction of LED train stimulation is illustrative. Representative images on the right show an example of optic fiber positioning (scale bar is 500 µm). b Example images from the same mouse showing the retrograde expression of PPO-Venus (yellow) in somas of the expected input regions containing CRH-releasing neurons (scale bars are 200 µm). Comparable expression was found in n = 5 infected mice. c Example of a polysomnographic recording with photoinhibition of CRH release in TRN during baseline and stimulation in the same mouse. The hypnograms at the top indicate the vigilance states and the occurrence of microarousals (MAs, marked by red dots), with the corresponding sigma power at the bottom. Yellow-shaded areas indicate the timing of photostimulation. d PPO decreased the number of MAs, with no effect on the average sigma power (e) but an increase in delta power throughout NREMS (f). g The surge in sigma power at the transition to REMS was not affected by PPO (h) or the latency to REMS from the sigma peak (i). Data are represented as mean ± SEM and n = 5. Statistical analysis was performed by a two-tailed paired t-test, with *p < 0.05, **p < 0.01, ***p < 0.001. For additional statistical information, see Supplementary Table 1. Source data are provided as a Source data file.