Skip to main content
. 2021 Jun 18;4:761. doi: 10.1038/s42003-021-02239-2

Fig. 4. Altered spontaneous action potential firing in the SCN of WT and neuropeptide signaling-deficient mice and its manipulation by SVE.

Fig. 4

Box plots overlaid with dot plots (a, c), example recordings (b, d), and topographical heatmaps (e, f) showing multiunit MEA recordings of spontaneous action potential firing at (~CT13 for non-SVE control mice, 1 h following onset of wheel availability/onset of activity for SVE Vipr2−/− animals, and either 1 h following the onset of wheel availability (SVE(1)) or onset of behavior (drinking; SVE(2)) in WT mice). Also see Fig. S5. In the dorsal SCN subregion, firing rate varied across genotypes and exercise condition (1-way ANOVA; p < 0.0001) (see also Table S1). In the WT SCN, scheduled exercise did not alter action potential frequency in the dorsal subregion (mean ± SEM; 3.1 ± 0.3, 3.2 ± 0.4, and 2.1 ± 0.4 Hz, respectively, for non-SVE, SVE(1), and SVE(2) (n = 48, 54, and 45 recording electrodes); both p > 0.05; a, b; Table S1). Firing rate in the Vipr2−/− dorsal SCN did not differ from WT mice (p > 0.05), but scheduled exercise reduced spontaneous action potential frequency (3.8 ± 0.5 vs. 2.3 ± 0.3 Hz; n = 59 and 67; p = 0.041 a, b). In the ventral subregion, firing rate varied across genotypes and exercise condition (1-way ANOVA; <0.0001). In the WT ventral SCN, action potential frequency was reduced by scheduled exercise in the SVE(1) condition (8.8 ± 1.1 vs. 4.9 ± 0.6 Hz; n = 35 and 47, p = 0.01) but not in the SVE(2) group (6.8 ± 0.7 Hz; n = 48, p > 0.05; c, d). In the Vipr2−/− ventral SCN, spontaneous firing rate was lower than WT (p < 0.0001), but scheduled exercise did not significantly alter firing rate (1.9 ± 0.3 vs. 1.1 ± 0.2 Hz; n = 47 and 45; p > 0.05; c, d). Heatmaps show average firing (e) and differences in firing between non-SVE WT and Vipr2−/− SCN (f). Horizontal red lines in b, d show detection threshold at −17 µV. Gray shaded boxes in a, c represent the interquartile distance between the upper and lower quartile with the median plotted as a horizontal line within the box. Whiskers depict the lower quartile − 1.5 × interquartile distance and upper quartile + 1.5 × interquartile distance. Individual data points are overlaid. Recordings were made from six SCN-containing brain slices from WT non-SVE mice, and seven slices each from WT SVE(1), WT SVE(2), Vipr2−/− non-SVE, and Vipr2−/− SVE mice. *p < 0.05; **p < 0.01; ****p < 0.0001. Also see Fig. S4. Further details of statistical outcomes are in Table S1.