title: Diurnal rhythm of H+-peptide cotransporter in rat small intestine.
abstract: In mammals, most physiological, biochemical, and behavioral processes show a circadian rhythm. In the present study, we examined the diurnal rhythm of the H+-peptide cotransporter (PEPT1), which transports small peptides and peptide-like drugs in the small intestine and kidney, using rats maintained in a 12-h photoperiod with free access to chow. The transport of [14C]glycylsarcosine (Gly-Sar), a typical substrate for PEPT1 by in situ intestinal loop and everted intestine, was greater in the dark phase than the light phase. PEPT1 protein and mRNA levels varied significantly, with a maximum at 2000 and minimum at 800. Similar functional and expressional diurnal variations were observed in the intestinal Na+-glucose cotransporter (SGLT1). In contrast, renal PEPT1 and SGLT1 showed little diurnal rhythmicity in protein and mRNA expression. These findings indicate that the intestinal PEPT1 undergoes diurnal regulation in its activity and expression, and this could affect the intestinal absorption of dietary protein.
authors.affiliation: Department of Pharmacy, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto 606 - 8507, Japan.
authors.forename: Xiaoyue
authors.initials: X
authors.lastname: Pan
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Terada
authors.forename: Megumi
authors.initials: M
authors.lastname: Irie
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saito
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Inui
mesh_terms: D000042:Absorption; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002940:Circadian Rhythm; D004151:Dipeptides / Q000493:pharmacokinetics; D004386:Duodenum / Q000378:metabolism*; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D000074011:Peptide Transporter 1; D017440:Photoperiod; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D051269:Sodium-Glucose Transporter 1; D027981:Symporters / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D004151:Dipeptides; D008562:Membrane Glycoproteins; D009004:Monosaccharide Transport Proteins; D000074011:Peptide Transporter 1; D012333:RNA, Messenger; C489940:Slc15a1 protein, rat; C495676:Slc5a1 protein, rat; D051269:Sodium-Glucose Transporter 1; D027981:Symporters; C093694:hydrogen-coupled oligopeptide transporter PepT2; C004194:glycylsarcosine