Fig. 4: CCK-Ca2+ rhythm in VIP-deficient mice rapidly attenuates in DD.
From: Neuronal feedback loop of the suprachiasmatic nucleus generates robust circadian rhythms
a Schematic diagram of viral vector (AAV-CAG-FLEX-jGCaMP7s and AAV-TRE-jRGECO1a) injection and optical fiber implantation at the SCN in control (Cckwt/ires-Cre; Vipwt/tTA) or VIP-deficient mice (Cckwt/ires-Cre; ViptTA/tTA) for fiber photometry recording. b A representative coronal SCN section of mice with jGCaMP7s expression in CCK neurons and jRGECO1a in VIP neurons. A white dotted square shows the estimated position of the implanted optical fiber. Green, jGCaMP7s; magenta, jRGECO1a. Scale bar, 200 μm. Similar images were consistently observed across all mice used in this experiment. c Representative plots of the in vivo jGCaMP7s signal of CCK neurons (CCK-Ca2+, green) and jRGECO1a signal of VIP neurons (VIP-Ca2+, magenta) overlaid with the locomotor activity (black) in actograms. Detrended Ca2+ signals are shown with normalization in each row. Control and VIP-deficient mice were initially housed in 12:12-h LD and then in DD. Gray shading indicates the time when the light was off. Time courses of CCK-Ca2+ (d) and VIP-Ca2+ (e) rhythms for 26 days (6 days in LD, 20 days in DD). Detrended and smoothened data from control (lavender) or VIP-deficient (orange) mice are shown. f Averaged periodogram of detrended CCK-Ca2+ (green), VIP-Ca2+ (magenta) signals and the locomotor activity (black) of control and VIP-deficient mice for days 1–20 in DD (10-min bins). Gray line, significance level; black dotted line, 24 h. Time courses of periods (g) and amplitudes (Qp) (h) of CCK-Ca2+ (green), VIP-Ca2+ (magenta), and the locomotor activity (black) rhythms in DD by sequential periodogram analyses with shifting 5-day windows. *p < 0.05, **p < 0.01 by two-way repeated measures ANOVA; ns, not significant. Values are mean ± SEM. n = 3 for control; n = 6 for VIP-deficient mice (d–h). The exact p-values are as follows: LD, 0.1034; DD, 0.0018 (d), LD, 0.1242; DD, 0.0057 (e), Control, 0.6993; VIP-deficient, CCK-Ca2+ vs. VIP-Ca2+, 0.2802, CCK-Ca2+ vs. Locomotor activity, 0.0825, VIP-Ca2+ vs. Locomotor activity, >0.9999 (g). Gray lines indicate the 99.9% confidence levels in χ2 periodograms (f, h). Source data are provided as a Source data file.
