Fig. 6.

Cysteine administration induces a phase advance of the liver circadian clocks via increased IGF-1 production in the liver. (a) Experimental schedule. The green arrows indicate oral administration time of 0.5% CMC (Control) or Cysteine at ZT 5 for 3 consecutive days. The orange arrow indicates fasting. (b) Relative hepatic mRNA expression levels; the left graph shows IGF-1 levels at 6 time points per day. The right graph shows average IGF-1 levels at all time points (c) in the liver, and (d) in the serum. The Control and Cysteine groups at each point: n = 5. Data are presented as the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 by the Student t-test; ^#P < 0.05, ^##P < 0.01 (vs. Control) by the Mann-Whitney test. ^&P < 0.05 (vs. Control) by two-way ANOVA with Sidak post-hoc test.