Brain prostanoid TP receptor-mediated adrenal noradrenaline secretion and EP3 receptor-mediated sympathetic noradrenaline release in rats.
Sympathetic nerves release noradrenaline, whereas adrenal medullary chromaffin cells secrete noradrenaline and adrenaline. Therefore, plasma noradrenaline reflects the secretion from adrenal medulla in addition to the release from sympathetic nerves, however the exact mechanisms of adrenal noradrenaline secretion remain to be elucidated. The present study was designated to characterize the source of plasma noradrenaline induced by intracerebroventricularly (i.c.v.) administered bombesin and prostaglandin E2 in urethane-anesthetized rats. Bombesin (1.0 nmol/animal, i.c.v.) elevated plasma noradrenaline and adrenaline, while prostaglandin E2 (0.3 nmol/animal, i.c.v.) elevated only plasma noradrenaline. The bombesin-induced elevations of both catecholamines were attenuated by pretreatments with furegrelate (an inhibitor of thromboxane A2 synthase) [250 and 500 microg (0.9 and 1.8 micromol)/animal, i.c.v.)] and [(+)-S-145] [(+)-(1R,2R,3S,4S)-(5Z)-7-(3-[4-3H]-phenylsulphonyl-aminobicyclo[2.2.1]hept-2-yl)hept-5-enoic acid sodium salt] (an antagonist of prostanoid TP receptors) [100 and 250 microg (250 and 625 nmol)/animal)], and abolished by acute bilateral adrenalectomy. On the other hand, the prostaglandin E2-induced elevation of plasma noradrenaline was not influenced by acute bilateral adrenalectomy. These results suggest that adrenal noradrenaline secretion and sympathetic noradrenaline release are mediated by differential central mechanisms; brain prostanoid TP receptors activated by bombesin are involved in the adrenal noradrenaline secretion, while brain prostanoid EP (probably EP3) receptors activated by prostaglandin E2 are involved in the sympathetic noradrenaline release in rats. Brain prostanoid TP receptors activated by bombesin are also involved in the adrenal adrenaline secretion.
Yokotani
Keiko
K
Department of Neuropharmacology, Program of Neural Integration, Graduate School of Medicine, Kochi University, Nankoku, Kochi 783-8505, Japan. yokotani@med.kochi-u.ac.jp
Okada
Shoshiro
S
Nakamura
Kumiko
K
Yamaguchi-Shima
Naoko
N
Shimizu
Takahiro
T
Arai
Junichi
J
Wakiguchi
Hiroshi
H
Yokotani
Kunihiko
K
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000315:Adrenalectomy; D000818:Animals; D001572:Benzofurans / Q000494:pharmacology; D001839:Bombesin / Q000008:administration & dosage / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D001643:Bridged Bicyclo Compounds / Q000494:pharmacology; D015232:Dinoprostone / Q000008:administration & dosage / Q000494:pharmacology; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D009638:Norepinephrine / Q000097:blood / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018078:Receptors, Prostaglandin E / Q000502:physiology*; D058308:Receptors, Prostaglandin E, EP3 Subtype; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism*; D013930:Thromboxane-A Synthase / Q000037:antagonists & inhibitors
D001572:Benzofurans; D001643:Bridged Bicyclo Compounds; D005229:Fatty Acids, Monounsaturated; D018078:Receptors, Prostaglandin E; D058308:Receptors, Prostaglandin E, EP3 Subtype; D017482:Receptors, Thromboxane; C056566:S 145; D013930:Thromboxane-A Synthase; D015232:Dinoprostone; C039936:furegrelate; D001839:Bombesin; D009638:Norepinephrine