Melanopsin Regulates Both Sleep-Promoting and Arousal-Promoting Responses to Light
A Fos induction in response to a 30 min light pulse was studied in wildtype mice exposed to blue or green light in both the SCN and VLPO (two-way ANOVA for wavelength x brain region interaction F(2,31) = 10.968 p ≤ 0.001). Mice exposed to blue light show greater Fos induction in the SCN compared with green light (posthoc Tukey dark versus blue p = 0.001, dark versus green p = 0.035, blue versus green p = 0.008). By contrast, in the VLPO, a greater response to green light than blue light was observed (dark versus blue p = 0.880, dark versus green p = 0.015). As a control, Gal induction was also studied, showing no induction in the SCN but significant induction in the VLPO (two-way ANOVA for wavelength and x brain region interaction F(2,30) = 3.774 p = 0.035). This response was only evident in response to green light (posthoc Tukey dark versus blue p = 0.742, dark versus green p = 0.011, blue versus green p = 0.003). Histograms show mean ± SEM, n = 5–8/group. Significant differences indicated by *** p ≤ 0.001, ** p ≤0.01, * p ≤0.05, NS = not significant. The data used to make this figure can be found in S6 Data.