Circadian Insulin, GH, Prolactin, Corticosterone and Glucose Rhythms in Fed and Fasted Rats

Abstract

The effects of short term food deprivation on circadian plasma insulin, growth hormone, corticosterone and glucose patterns were studied in male rats. Insulin in the fed controls increased significantly during the latter part of the light phase as previously reported. Insulin in fasted rats also increased significantly during the latter part of the light phase but levels were below fed animals. The late afternoon increase of insulin in fed and fasted animals was not being driven by the glucose rhythms but plasma glucose appeared responsive to insulin changes. Growth hormone and prolactin were significantly elevated in fasting animals during part of the day as compared to fed animals. Corticosterone patterns were similar in fed and fasted animals.