Variations of meal-to-meal liver glycogen in rats

Liver glycogen content was determined in free feeding rats sacrificed at the beginning of nocturnal meals or 60 min later. It was found that the glycogen content at the beginning of meals and 60 min later was highly correlated with the cumulative food intake since the beginning of the dark cycle, and therefore, increased from meal to meal. The comparison of these correlations between the cumulative food intake and the liver glycogen at the beginning of the meal and 60 min after ruled out the possibility that a constant decrement of glycogen might be involved in both meal onset and prandial periodicity of feeding. Rather the results are consistent with the view that the glycogen load during the night is a minute carbohydrate store which, like the fat store, is involved in the diurnal 12/12 hr feeding periodicity.