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ROLE OF BRAIN PROSTANOIDS IN GLUCAGON‐LIKE PEPTIDE‐1‐INDUCED CENTRAL ACTIVATION OF SYMPATHO‐ADRENOMEDULLARY OUTFLOW IN RATS
Author(s) -
Arai Junichi,
Okada Shoshiro,
Yamaguchishima Naoko,
Shimizu Takahiro,
Sasaki Tsuyoshi,
Yorimitsu Mieko,
Wakiguchi Hiroshi,
Yokotani Kunihiko
Publication year - 2008
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2008.04957.x
Subject(s) - medicine , endocrinology , chemistry , thromboxane , antagonist , catecholamine , receptor antagonist , glucagon like peptide 1 , cyclooxygenase , receptor , thromboxane b2 , platelet , diabetes mellitus , enzyme , type 2 diabetes , biochemistry
SUMMARY1 The aim of the present study was to characterize the source of plasma catecholamines induced by centrally administered glucagon‐like peptide‐1 (GLP‐1), with regard to brain prostanoids, in urethane‐anaesthetized rats. 2 Glucagon‐like peptide‐1 and other compounds were administered intracerebroventricularly (i.c.v.) and blood samples were collected via a cannula inserted into the femoral artery. Catecholamines were extracted from plasma with activated alumina and were assayed electrochemically using high‐performance liquid chromatography. 3 At 0.3, 1.0 and 3.0 nmol/animal, GLP‐1 dose‐dependently elevated plasma levels of noradrenaline and adrenaline and the 1.0 nmol GLP‐1‐induced response was dose‐dependently reduced by 5 and 10 nmol/animal exendin (5–39), a selective GLP‐1 receptor antagonist. The GLP‐1‐induced elevation of concentrations of both catecholamines was abolished by 1.2 µmol/animal indomethacin, an inhibitor of cyclo‐oxygenase, whereas 1.2 µmol/animal baicalein, a lipoxygenase inhibitor, had no effect. 4 Both furegrelate (1.8 µmol/animal; an inhibitor of thromboxane A 2 synthase) and (+)S‐145 (625 nmol/animal; a thromboxane A 2 receptor antagonist) attenuated the GLP‐1‐induced increases in plasma adrenaline concentrations, but had no effect on the increases in plasma noradrenaline. The GLP‐1‐induced increase in plasma adrenaline concentrations was abolished by acute bilateral adrenalectomy, but the procedure had no effect on increases in plasma noradrenaline. 5 These results suggest that, in rats, centrally administered GLP‐1 induces the secretion of adrenaline from the adrenal medulla by brain thromboxane A 2 ‐mediated mechanisms, whereas the peptide evokes the release of noradrenaline from sympathetic nerves by brain prostanoids via mechanisms other than those mediated by thromboxane A 2 .