Intestinal nutrient-gene interaction: The effect of feed refeeding on cholecystokinin and proglucagon gene deprivation and expression

tested the hypothesis that dietary components reaching the bovine small int estine influence the expression of genes that encode the gastrointestinal n europeptides cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1). The amount of digesta reaching the intestine was manipulated during the experi ment by withholding feed from five heifers fitted with ruminal, duodenal, a nd ileal cannulas for 48 h and then subsequent refeeding. Duodenal and ilea l biopsies were collected using a fiber-optic endoscope. A Northern hybridi zation procedure was used to evaluate changes in gene expression. Blood con centrations of CCK and GLP-1 were determined with RIA. The data indicate th at CCK blood concentration and mRNA abundance decreased during the period o f feed deprivation, but they returned to predeprivation values within 16 to 24 h of refeeding. The GLP-1 blood concentration also decreased during fee d deprivation and returned to predeprivation values within 4 to 8 h of refe eding, despite the fact that proglucagon mRNA abundance did not change sign ificantly during feed deprivation and refeeding. These findings provide evi dence that CCK and GLP-1 are released in response to nutrients that reach t he small intestine and may be involved in the physiological process of dige stion and possibly play a role in regulating feed intake in ruminants.