Ghrelin suppresses noradrenaline release in the brown adipose tissue of rats.
To clarify the role of ghrelin in the regulatory mechanism of energy metabolism, we analyzed the effects of centrally and peripherally administered ghrelin on noradrenaline release in the brown adipose tissue (BAT) of rats using a microdialysis system. I.c.v. administration of ghrelin at a dose of 500 pmol suppressed noradrenaline release in BAT, and microinjection of ghrelin (50 pmol) into the paraventricular nucleus (PVN) or arcuate nucleus (ARC) of the hypothalamus also suppressed noradrenaline release in BAT. In addition, i.v. administered ghrelin (30 nmol) suppressed noradrenaline release in BAT, and this suppression was blocked by a vagotomy. Neither i.c.v. nor i.v. administration of des-acyl ghrelin, which does not bind to GH secretagogue receptor type 1a (GHS-R1a), affected noradrenaline release in BAT. These results indicate that ghrelin increases energy storage by suppressing the activity of the sympathetic nerve innervating BAT. It seems that the PVN and ARC, which express GHS-R1a, are the sites of action of ghrelin in the brain and that the action of peripheral ghrelin on the sympathetic nerve activity innervating BAT is mediated by the vagal nerve, which also expresses GHS-R1a.
Department of Physiology, Nippon Medical School, Bunkyo-ku, Tokyo, Japan. asuka@nms.ac.jp
Asuka
A
Mano-Otagiri
Hisayuki
H
Ohata
Azusa
A
Iwasaki-Sekino
Takahiro
T
Nemoto
Tamotsu
T
Shibasaki
D002001:Adipose Tissue, Brown / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D054439:Ghrelin / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D008297:Male; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D009638:Norepinephrine / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D054440:Receptors, Ghrelin / Q000235:genetics / Q000378:metabolism; D000071256:Uncoupling Protein 1; D014630:Vagus Nerve / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
D054439:Ghrelin; D007473:Ion Channels; D024101:Mitochondrial Proteins; D054440:Receptors, Ghrelin; D000071256:Uncoupling Protein 1; D009638:Norepinephrine