Effects of centrally administered prostaglandin E3 and thromboxane A3 on plasma noradrenaline and adrenaline in rats: Comparison with prostaglandin E2 and thromboxane A2

Previously, we reported the involvement of brain omega-6 prostanoids, especially prostaglandin E-2 and thromboxane A(2), in the activation of central sympatho-adrenomedullary outflow in rats. omega-3 Prostanoids, including prostaglandin E-3 and thromboxane A(3), are believed to be less bioactive than omega-6 prostanoids, although studies on the functions of omega-3 prostanoids in the central nervous system have not been reported. In the present study, therefore, we compared the effects of centrally administered omega-3 prostanoids, prostaglandin E-3 and thromboxane A(3), with those of omega-6 prostanoids, prostaglandin E-2 and thromboxane A(2), on the plasma catecholamines in anesthetized rats. Intracerebroventricularly (i.c.v.) administered prostaglandin E-2 (0.15, 0.3 and 1.5 nmol/animal) and prostaglandin E-3 (0.3 and 3 nmol/animal) predominantly elevated plasma noradrenaline but not adrenaline, but the latter was less efficient than the former. On the other hand, U-46619 (an analog of thromboxane A(2)) (30, 100 and 300 nmol/animal, i.c.v.) and Delta(17)-U-46619 (an analog of thromboxane A(3)) (100 and 300 nmol/animal, i.c.v.) both elevated plasma catecholamines (adrenaline >> noradrenaline) to the same degree. These results suggest that centrally administered prostaglandin E-3 is less effective than prostaglandin E-2 to elevate plasma noradrenaline, and that thromboxane A(3) is almost as equipotent as thromboxane A(2) to elevate plasma catecholamines in rats. (C) 2009 Elsevier B.V. All rights reserved.