GLP-2 potentiates L-type Ca<sup>2+</sup> channel activity associated with stimulated glucose uptake in hippocampal neurons

  • Yi Wang
    State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, China;
  • Xinfu Guan
    United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics; and

抄録

<jats:p> Glucagon-like peptide-2 (GLP-2) is a neuropeptide secreted from endocrine cells in the gut and neurons in the brain. GLP-2 stimulates intestinal crypt cell proliferation and mucosal blood flow while decreasing gastric emptying and gut motility. However, a GLP-2-mediated signaling network has not been fully established in primary cells. Since the GLP-2 receptor mRNA and protein were highly expressed in the mouse hippocampus, we further characterized that human <jats:sup>125</jats:sup>I-labeled GLP-2<jats:sub>1–33</jats:sub> specifically bound to cultured hippocampal neurons with K<jats:sub>d</jats:sub> = 0.48 nM, and GLP-2 acutely induced subcellular translocalization of the early gene c-Fos. Using the whole cell patch clamp, we recorded barium currents ( I<jats:sub>Ba</jats:sub>) flowing through voltage-gated Ca<jats:sup>2+</jats:sup> channels (VGCC) in those neurons in the presence of GLP-2 with and without inhibitors. We showed that GLP-2 (20 nM) enhanced the whole cell I<jats:sub>Ba</jats:sub> mediated by L-type VGCC that was defined using an L-type Ca<jats:sup>2+</jats:sup> channel blocker (nifedipine, 10 μM). Moreover, GLP-2-potentiation of L-type VGCC was abolished in neurons pretreated with a PKA inhibitor (PKI<jats:sub>14–22</jats:sub>, 1 μM). Finally, using a fluorescent nonmetabolized glucose analog (6-NBDG) tracing imaging, we showed that glucose was taken up directly by cultured neurons. GLP-2 increased 2-deoxy-d-[<jats:sup>3</jats:sup>H]glucose uptake that was dependent upon dosage, activation of PKA, and potentiation of L-type VGCC. We conclude that GLP-2 potentiates L-type VGCC activity through activating PKA signaling, partially stimulating glucose uptake by primary cultured hippocampal neurons. The potentiation of L-type VGCC may be physiologically relevant to GLP-2-induced neuroendocrine modulation of neurotransmitter release and hormone secretion. </jats:p>

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