The effects of postoperative time intervals and diurnal variation on liver glycogen levels in rats with hippocampal lesions

Abstract

Liver glycogen levels were measured in rats with hippocampal lesions and in control animals. Liver glycogen levels were determined each week for the first ten postoperative weeks and eight months postoperatively. It was found that after one week, control animals and animals with hippocampal lesions were not significantly different in liver glycogen levels. By the end of the second week the group with hippocampal lesions was significantly higher than the control animals. This variation pattern continued during the third week. By the end of the third week the animals with hippocampal ablations had reached their highest level, which remained unchanged throughout the rest of the series. No significant changes in liver glycogen levels were obtained in the control animals. Liver glycogen levels were then measured in normal rats and rats with hippocampal lesions maintained on a diurnal rhythm of twelve light hours followed by twelve dark hours. One month postoperatively, rats with hippocampal lesions had a significantly higher liver glycogen level at all time periods as compared with normal animals. Both groups of rats showed the diurnal pattern of higher levels of liver glycogen in the beginning of the light phase and lower levels of liver glycogen in the beginning of the dark phase. The observed variations may be explained in terms of alterations in known homeostatic mechanisms controlling liver glycogen levels.