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Exendin-4 increases blood glucose levels acutely in rats by activation of the sympathetic nervous system.
Am. J. Physiol. Endocrinol. Metab. 298, E1088-E1096 (2010)
Exendin-4 (Ex-4), an agonist of the glucagon-like peptide-1 receptor (GLP-1R), shares many of the actions of GLP-1 on pancreatic islets, the central nervous system (CNS), and the gastrointestinal tract that mediates glucose homeostasis and food intake. Because Ex-4 has a much longer plasma half-life than GLP-1, it is an effective drug for reducing blood glucose levels in patients with type 2 diabetes mellitus (T2DM). Here, we report that acute administration of Ex-4, in relatively high doses, into either the peripheral circulation or the CNS, paradoxically increased blood glucose levels in rats. This effect was independent of the insulinotropic and hypothalamic-pituitary-adrenal activating actions of Ex-4 and could be blocked by a GLP-1R antagonist. Comparable doses of GLP-1 did not induce hyperglycemia, even when protected from rapid metabolism by a dipeptidyl peptidase IV inhibitor. Acute hyperglycemia induced by Ex-4 was blocked by hexamethonium, guanethidine, and adrenal medullectomy, indicating that this effect was mediated by sympathetic nervous system (SNS) activation. The potency of Ex-4 to elevate blood glucose waned with chronic administration such that after 6 days the familiar actions of Ex-4 to improve glucose tolerance were evident. These findings indicate that, in rats, high doses of Ex-4 activate a SNS response that can overcome the expected benefits of this peptide on glucose metabolism and actually raise blood glucose. These results have important implications for the design and interpretation of studies using Ex-4 in rats. Moreover, since there are many similarities in the response of the GLP-1R system across mammalian species, it is important to consider whether there is acute activation of the SNS by Ex-4 in humans.
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Publikationstyp
Artikel: Journalartikel
Dokumenttyp
Wissenschaftlicher Artikel
Sprache
englisch
Veröffentlichungsjahr
2010
HGF-Berichtsjahr
0
ISSN (print) / ISBN
0193-1849
e-ISSN
1522-1555
Quellenangaben
Band: 298,
Heft: 5,
Seiten: E1088-E1096
Verlag
American Physiological Society
Begutachtungsstatus
Peer reviewed
Institut(e)
Institute of Diabetes and Obesity (IDO)
PubMed ID
20197503
WOS ID
000276635200020
Erfassungsdatum
2010-12-31