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Postnatal development of circadian rhythms in disaccharidase activities in rat small intestine
Insights
Circadian rhythms in rat small intestine maltase and lactase activity emerge after weaning. Feeding time influences these enzyme rhythms, with higher activity observed at night in adults and around feeding times when restricted.
Area of Science:
- Physiology
- Biochemistry
- Chronobiology
Background:
- Circadian rhythms regulate physiological processes, including digestive enzyme activity.
- Postnatal development involves significant changes in gut function and metabolic regulation.
Purpose of the Study:
- To investigate the ontogeny of circadian rhythms in rat small intestinal maltase and lactase activity.
- To determine the influence of feeding patterns on these developing circadian rhythms.
Main Methods:
- Enzyme activity assays for maltase and lactase were performed on rat small intestine samples.
- Experiments involved different feeding regimens (ad libitum, daytime restriction) across postnatal developmental stages.
Main Results:
- No significant circadian rhythm in maltase or lactase activity was observed during the suckling or weaning periods under ad libitum feeding.
- Circadian rhythms with higher nocturnal activity, similar to adults, appeared several days post-weaning.
- Restricted daytime feeding post-weaning shifted the enzyme activity rhythm to coincide with feeding times.
Conclusions:
- Circadian regulation of small intestinal maltase and lactase activity in rats is established post-weaning.
- Feeding schedules play a crucial role in entraining these digestive enzyme circadian rhythms during development.
Abstract:
The circadian rhythms in the activities of maltase and lactase of the small intestine were examined at various stages of postnatal development in rats. When the rats were fed ad libitum, no circadian change in the enzyme activities was found during the suckling period or the weaning period. However, several days after the time of weaning, the enzymes showed the same circadian changes as in adult rats with higher activities at night. After weaning, when the rats were fed only during the daytime, the phase of the enzyme rhythm shifted about half a day, and the highest activity was observed around feeding time. However, during the suckling period, no circadian rhythm in the enzyme acvities was found, even when the rats were allowed to feed only during a restricted time of the day.