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Pharm Res. 2001 Jun;18(6):807-13.

PEPT2-mediated uptake of neuropeptides in rat choroid plexus.

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  • 1College of Pharmacy and Upjohn Center for Clinical Pharmacology, The University of Michigan, Ann Arbor 48109, USA.

Abstract

PURPOSE:

The peptide transporter PEPT2 was recently shown to be functionally active in rat choroid plexus, suggesting that it may play a role in neuropeptide homeostasis in the cerebrospinal fluid. This study, therefore, examined the role of PEPT2 in mediating neuropeptide uptake into choroid plexus.

METHODS:

Whole-tissue rat choroid plexus uptake studies were performed on GlySar in the absence and presence of neuropeptides and on carnosine.

RESULTS:

The neuropeptides NAAG, CysGly, GlyGln, kyotorphin, and carnosine inhibited the uptake of radiolabeled GlySar at 1.0 mM concentrations. In contrast, TRH, [D-Arg2]-kyotorphin, glutathione, and homocarnosine did not inhibit GlySar uptake. Kyotorphin, an analgesic, was a competitive inhibitor of GlySar with a Ki of 8.0 microM. The direct uptake of carnosine was also shown to be mediated by PEPT2 in isolated choroid plexus (Km = 39.3 microM; Vmax = 73.9 pmol/mg/min). Radiolabeled carnosine uptake was inhibited by 1.0 mM concentrations of GlySar or carnosine but not homocarnosine, L-histidine, or beta-alanine.

CONCLUSIONS:

These findings indicate that PEPT2 mediates the uptake of a diverse group of neuropeptides in choroid plexus, and suggests a role for PEPT2 in the regulation of neuropeptides, peptide fragments, and peptidomimetics in cerebrospinal fluid.

PMID:
11474785
[PubMed - indexed for MEDLINE]
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