Fig. 7. Serotonin levels (+S.E.M.) in the brain (protocerebrum, antennal
lobe and optic lobe) of B. mori exposed to a 16 h:8 hlight:dark
cycle, at different time points over 24 h. The period during which the light
was turned off is indicated by a gray bar along the x-axis. The
N values for each group varied between 6 and 9. There was a circadian
variation of serotonin in the brain (one-way ANOVA, P<0.05).