The effects of meal-feeding at different times of the day on daily changes in serum insulin, gastrin and liver enzymes in the rat.

Restricted feeding at two distinct times of the day was associated with different adaptive responses in rats. Animals meal-fed from 1400 to 1800 hours for 6 days demonstrated feeding-cued circadian rhythms in liver weight and in liver transaminase and lactic dehydrogenase enzyme activities. Daily fluctuations in the levels of blood immunoreactive insulin and gastrin were also found to be cued by food intake. By comparison, rats fed from 0700 to 1100 hours for 6 days exhibited altered liver function and blood immunoreactive gastrin patterns. It is suggested that meal-feeding in rats is associated with certain adaptive responses which are dependent upon the timing of the meal. The observed metabolic alterations consequent to meal-feeding are much more apparent in morning-fed than in afternoon-fed animals.