[Ontogenetic changes in the circadian rhythm of plasma insulin and its correlation to food intake]

In experiments with laboratory mice of different age (3, 9, 13, 18, 31 and 52 weeks old) directed changes of the daily pattern of plasma insulin concentration depending on the development stage of the animals could be quantified. The circadian acrophase undergoes a negative shift from the end of dark/beginning of light period in 3-weeks-old mice to the end of light/beginning of dark period in adults. The amplitude decreases up to an age of 9 weeks, whereas the amount of ultradian components is high, and increases during further development. Similar changes could be obtained for the daily pattern of feeding activity, occurring however some weeks earlier. The result is a temporary desynchronisation. In adult animals the phase correlations are relatively stable. The plasma insulin concentration reaches its maximal value before the maximum of feeding activity, thus stimulating a high food consumption and utilisation rate.