Chronobioassay of synthetic short-chain ACTH 1-17 (synchrodyn) effect upon circadian characteristics of murine liver glycogen

Metabolic Synchrodyn effects can be assayed by liver glycogen content in intact female mice when Synchrodyn is given in certain circadian stages, but not when it is given at other times. The phenomenon of stage-dependence of Synchrodyn responses characterizes the effects of this peptide upon the mesor, amplitude and acrophase of the circadian rhythm in liver glycogen. These findings broaden the scope of Synchrodyn effects at the cellular level. The results also demonstrate a chronobioassay: a fixed dose of the compound investigated yields statistically significant effects upon certain rhythm characteristics at some circadian stages but not at others. More specifically, effects upon mesor are found at times different from those at which other characteristics are affected; for the same characteristic, the acrophase, the effect may be an advance at one time and a delay at another.