Neuromedin U facilitates oxytocin release from the pituitary via beta adrenoceptors.
Neuromedin U activates noradrenergic neurones in the medulla oblongata and oxytocin neurones in the hypothalamus. Here we examined roles of noradrenergic transmission in oxytocin release from the pituitary after intracerebroventricular administration of neuromedin U in rats. Neuromedin U administration facilitated noradrenaline release in the supraoptic nucleus. Administration of a beta1 adrenoceptor antagonist, metoprolol, or a beta2 antagonist, ICI 118551 but not an alpha1 antagonist, benoxathian, reduced increases in plasma oxytocin concentrations observed after administration of neuromedin U, but plasma ACTH concentrations were not significantly changed. All theses data suggest that neuromedin U stimulates oxytocin release from the pituitary, at least in part, via activation of beta adrenoceptors.
Rokkaku
Kumiko
K
Department of Medicine, Jichi Medical School, Tochigi-ken, Japan.
Onaka
Tatsushi
T
Okada
Nobukazu
N
Ideno
Junichi
J
Kawakami
Akio
A
Honda
Kazufumi
K
Yada
Toshihiko
T
Ishibashi
Shun
S
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D007276:Injections, Intraventricular; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D017551:Microdialysis; D009479:Neuropeptides / Q000494:pharmacology*; D010121:Oxytocin / Q000097:blood / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D011412:Propanolamines; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D009479:Neuropeptides; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; C056900:neuromedin U; C026777:ICI 118551; D010121:Oxytocin; D000324:Adrenocorticotropic Hormone; D008790:Metoprolol