Fig. 3: CRH release in the TRN exhibits an infraslow oscillatory pattern during NREMS.
a Left, diagram showing stereotactic injections of the GRABCRH sensor targeting TRN in one hemisphere and the CRH-insensitive control sensor, GRABCRHmut, in the contralateral hemisphere. Center, time-synchronized photometry recordings were carried out together with EEG/EMG recordings. Right, example image of optical fiber positioning over TRN and viral expression of GRABCRH (green) (the scale bar is 500 µm). b Example hypnogram throughout the vigilance states with concomitant GRABCRH (dark green) and GRABCRHmut (light green) ΔF/F signals in the TRN. Both GRABCRH and GRABCRHmut show a decrease in relative fluorescence during wakefulness and REMS. However, during NREMS, GRABCRH shows large oscillations that are not present with GRABCRHmut. c Right, close-up of GRABCRH and GRABCRHmut during NREMS. Left, quantification of the peak-to-peak amplitude between GRABCRH and GRABCRHmut, showing significantly different amplitudes (n = 4). d Power spectral density analysis of CRH release during NREMS shows an overlapping peak with the infraslow oscillation of sigma centered around 0.02 Hz. e Example trace of the time-matched CRH signal and the infraslow oscillation of sigma during NREMS. Continuous vertical gray lines indicate sigma peaks, and dotted vertical gray lines indicate sigma valleys. f Left, cross-correlation of the two signals shows that they anti-correlate, with maximal CRH release during NREMS overlapping with periods of low spindle activity corresponding to sleep fragility (n = 12). Right, the upper violin plots show the individual variability of the cross-correlation, each dot is the correlation coefficient (r) at lag 0 (left) and at the maximum correlation (max corr, right) for each mouse; the lower violin plot shows the distribution of the lag values at maximum correlation (lag at max corr). Data are represented as mean ± SEM or KDE for violin plots, with dashed lines indicating the median and dotted lines indicating the upper and lower quartiles. 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.
