title: Circadian rhythmicity in several small intestinal functions is independent of use of the intestine.
abstract: Fifty milliliters of a liquid diet were administered daily to rats in three different ways: 1) orally, beginning at 0000 h; 2) by continuous intravenous infusion; and 3) by discontinuous intravenous infusion from 0000 to 1400 h. Animals were killed every 6 h over a 24-h period. Activity profiles as a function of time of day were determined for the following small intestinal parameters; monosaccharide transport; five disaccharidases; alkaline phosphatase; gamma-glutamyltransferase; leucylnaphthylamide hydrolyzing activity; villus height and width; and number of columnar cells lining a villus section. Circadian rhythmicity as previously reported was observed for all parameters in rats fed orally for 7 days but was not observed in any parameters in rats fed by continuous infusion for 9 days. Rats fed by discontinuous infusion for 10 days maintained circadian rhythmicity in the following functions: monosaccharide transport; disaccharidase activities; and columnar cell number. Thus, rhythmicity in these functions can exist without nutrient delivery to the alimentary tract and presumably arises from involvement of a neuro-endocrine component. The other activities tested appear to require the alimentary tract for the existence of circadian rhythmicity.
mesh_terms: D000284:Administration, Oral; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D002452:Cell Count; D002940:Circadian Rhythm; D005526:Food, Formulated; D007263:Infusions, Parenteral; D007421:Intestine, Small / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007931:Leucyl Aminopeptidase / Q000378:metabolism; D008297:Male; D051381:Rats; D005723:gamma-Glutamyltransferase / Q000378:metabolism
chemical_list: D005723:gamma-Glutamyltransferase; D000469:Alkaline Phosphatase; D007931:Leucyl Aminopeptidase