Modulation of intestinal L-glutamate transport by luminal leptin

• Carmen Fanjul ^[1] ; Jaione Barrenetxe ^[1] ; María Pilar Lostao ^[1] ; Robert Ducroc ^[2]
  1. [1] Universidad de Navarra

     Universidad de Navarra

     Pamplona, España

     
  2. [2] French Institute of Health and Medical Research

     French Institute of Health and Medical Research

     París, Francia

     
• Localización: Journal of physiology and biochemistry, ISSN-e 1877-8755, ISSN 1138-7548, Vol. 71, Nº. 2 (June), 2015, págs. 311-317
• Idioma: inglés
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• Resumen

  • Leptin is secreted into the digestive tract and contributes to the absorption of dietary molecules by regulating transporters activity. Here, we studied the effect of luminal leptin on the intestinal transport of L-glutamate, an important component of human diet. We examined the effect of leptin on L-glutamate uptake in rat intestine in vitro measuring glutamate-induced short-circuit current (Isc) in Ussing chambers and L-[3H (U)]-glutamate uptake in jejunal everted rings. Glutamate-induced Isc was only observed in Na+-free conditions. This Isc was concentration (1–60 mmol L−1) and pH dependent. Luminal leptin increased glutamate Isc (∼100 %). Dose-response curve showed a biphasic pattern, with maximal stimulations observed at 10−13 and 10−10 mmol L−1, that were sensitive to leptin receptor antagonist. In everted rings, two glutamate transport mechanisms were distinguished: a Na+-dependent, H+-independent, that was inhibited by leptin (∼20 %), and a Na+-independent but H+-dependent, that was enhanced by leptin (∼20 %), in line with data obtained in Ussing chambers. Altogether, these data reveal original non-monotonic effect of luminal leptin in the intestine and demonstrate a new role for this hormone in the modulation of L-glutamate transport, showing that luminal active gut peptides can influence absorption of amino acids.