title: Brain opioid and nociceptin receptors are involved in regulation of bombesin-induced activation of central sympatho-adrenomedullary outflow in the rat.
abstract: Previously, we reported that central administration of bombesin, a stress-related peptide, elevated plasma levels of catecholamines (noradrenaline and adrenaline) in the rat. The sympatho-adrenomedullary system, which is an important component of stress responses, can be regulated by the central opioid system. In the present study, therefore, we examined the roles of brain opioid receptor subtypes (µ, δ, and κ) and nociceptin receptors, originally identified as opioid-like orphan receptors, in the bombesin-induced activation of central sympatho-adrenomedullary outflow using anesthetized male Wistar rats. Intracerebroventricularly (i.c.v.) administered bombesin-(1 nmol/animal) induced elevation of plasma catecholamines was significantly potentiated by pretreatment with naloxone (300 and 1000 µg/animal, i.c.v.), a non-selective antagonist for µ-, δ-, and κ-opioid receptors. Pretreatment with cyprodime (100 µg/animal, i.c.v.), a selective antagonist for µ-opioid receptors, also potentiated the bombesin-induced responses. In contrast, pretreatment with naltrindole (100 µg/animal, i.c.v.) or nor-binaltorphimine (100 µg/animal, i.c.v.), a selective antagonist for δ- or κ-opioid receptors, significantly reduced the elevation of bombesin-induced catecholamines. In addition, pretreatment with JTC-801 (30 and 100 µg/animal, i.c.v.) or J-113397 (100 µg/animal, i.c.v.), which are selective antagonists for nociceptin receptors, also reduced the bombesin-induced responses. These results suggest that brain µ-opioid receptors play a suppressive role and that brain δ-, κ-opioid, and nociceptin receptors play a facilitative role in the bombesin-induced elevation of plasma catecholamines in the rat. Thus, in the brain, these receptors could play differential roles in regulating the activation of central sympatho-adrenomedullary outflow.
authors.affiliation: Department of Neurosurgery, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Yawata
authors.affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Youichirou
authors.initials: Y
authors.lastname: Higashi
authors.affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan. shimizu@kochi-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shimizu
authors.affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Shimizu
authors.affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Department of Gastroenterology and Hepatology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Taniuchi
authors.affiliation: Department of Neurosurgery, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ueba
authors.affiliation: Department of Pharmacology, Kochi Medical School, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Motoaki
authors.initials: M
authors.lastname: Saito
mesh_terms: D000313:Adrenal Medulla / Q000502:physiology*; D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D001921:Brain / Q000378:metabolism*; D002395:Catecholamines / Q000097:blood; D009019:Morphinans / Q000008:administration & dosage; D009270:Naloxone / Q000008:administration & dosage; D009271:Naltrexone / Q000008:administration & dosage / Q000031:analogs & derivatives; D051381:Rats; D011957:Receptors, Opioid / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D000094942:Nociceptin Receptor
chemical_list: D001839:Bombesin; D002395:Catecholamines; D009019:Morphinans; D009270:Naloxone; D009271:Naltrexone; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; C051843:binaltorphimine; C058450:cyprodime; C055382:naltrindole; C000722285:Oprl1 protein, rat
keywords: Bombesin; Brain; Nociceptin receptor; Opioid receptor; Sympatho-adrenomedullary system