Abstract
1. We studied the effects of intracerebroventricular (i.c.v.) administration of prostaglandin E2 (PGE2) and its receptor subtype ligands on plasma levels of catecholamines in urethane-anaesthetized rats. 2. Administration of PGE2 (0.15, 0.3 and 1.5 nmol per animal, i.c.v.) dose-dependently elevated plasma levels of noradrenaline (NA), while the levels of adrenaline were not affected. 3. Administration of sulprostone (EP3/EP1 agonist) and misoprostol (EP3/EP2 agonist) effectively elevated plasma NA levels in a dose-dependent manner (0.1, 0.3, and 1.0 nmol per animal). Butaprost (EP2 agonist) (0.3, 1.0 and 3.0 nmol per animal) was without effect. 17-Phenyl-omega-trinor PGE2 (EP1/EP3 agonist) effectively elevated plasma NA levels only at its highest dose (1.0 nmol per animal), but this elevation was not attenuated by pretreatment with SC-19220 (selective EP1 antagonist) (20 nmol per animal, i.c.v.). 4. The potency of these test agents in elevating plasma levels of NA was as follows; misoprostol > sulprostone > PGE2 > > 17-phenyl-omega-trinor PGE2 > > > butaprost. These results suggest that activation of central prostanoid EP3-receptors induces central sympathetic outflow in rats.