Qandeel HG, Alonso F, Hernandez DJ, Duenes JA, Zheng Y, Scow JS, Sarr MG. Role of vagal innervation in diurnal rhythm of intestinal peptide transporter 1 (PEPT1).
J Gastrointest Surg 2009;
13:1976-85. [PMID:
19707837 PMCID:
PMC2830643 DOI:
10.1007/s11605-009-0984-6]
[Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 07/24/2009] [Indexed: 01/31/2023]
Abstract
BACKGROUND
Protein is absorbed predominantly as di/tripeptides via H(+)/peptide cotransporter-1 (PEPT1). We demonstrated previously diurnal variations in expression and function of duodenal and jejunal but not ileal PEPT1; neural regulation of this pattern is unexplored.
HYPOTHESIS
Complete abdominal vagotomy abolishes diurnal variations in gene expression and transport function of PEPT1.
METHODS
Twenty-four rats maintained in a 12-h light/dark room [6AM-6PM] underwent abdominal vagotomy; 24 other rats were controls. Four weeks later, mucosal levels of mRNA and protein were measured at 9AM, 3PM, 9PM, and 3AM (n = 6 each) by quantitative real-time PCR and Western blots, respectively; transporter-mediated uptake of dipeptide (Gly-Sar) was measured by the everted-sleeve technique.
RESULTS
Diurnal variation in mRNA, as in controls, was retained post-vagotomy in duodenum and jejunum (peak at 3PM, p < 0.05) but not in ileum. Diurnal variations in expression of protein and Gly-Sar uptake, however, were absent post-vagotomy (p > 0.3). Similar to controls, maximal uptake was in jejunum after vagotomy (V (max), nmol/cm/min: jejunum vs. duodenum and ileum; 163 vs. 88 and 71 at 3AM; p < 0.04); K (m) remained unchanged.
CONCLUSIONS
Vagal innervation appears to mediate in part diurnal variations in protein expression and transport function of PEPT1, but not diurnal variation in mRNA expression of PEPT1.
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