Influence of a dorsomedial hypothalamus lesion on the circadian changes in the enzyme development and activity of intestinal brushborder membranes in the rat.

Circadian changes in activities and electrophoretic pattern of the intestinal brushborder enzymes alkaline phosphatase (EC 3.1.3.1), isomaltase (EC 3.2.1.10) and sucrase (EC 3.2.1.26) of normal rats and of rats with a lesion of the dorsomedial hypothalamus (DMH-rats) were studied. In contrast to the rhythm found in normal rats, there are no significant differences between the average enzyme activities in the light or dark period for the DMH-rats. The peak ratio in the electrophoretic pattern for sucrase-isomaltase (SI) over pro-sucrase-isomaltase (pro-SI) changes over 24 hr with higher values during the active (dark) period of the normal rat. In DMH-rats this ratio is much higher, but no significant difference could be demonstrated between the values near the acrophase in these rats.