Neither intravenous nor intracerebroventricular administration of obestatin affects the secretion of GH, PRL, TSH and ACTH in rats.
To examine the effect of obestatin, a recently identified peptide derived from preproghrelin, on pituitary hormone secretion, obestatin was administered in anesthetized male rats. Intravenous administration of obestatin did not show any effect on plasma GH, PRL, ACTH and TSH levels. Since obestatin has been reported to have opposite effects of ghrelin in regulating food intake, gastric emptying and intestinal contractility, GH suppressive effect, which is opposite effect of ghrelin, was tested. Intravenous administration of GHRH or GHRP-2, a ghrelin receptor ligand, resulted in a marked plasma GH elevation. However obestatin did not show any effect on GHRH- or GHRP-2-induced GH rise. Furthermore intracerebroventricular administration of obestatin also did not influence plasma GH, PRL, ACTH and TSH levels. These findings suggest that obestatin has no effect on pituitary hormone secretions despite the presence of GPR39, a receptor for obestatin, in the pituitary.
Yamamoto
Daisuke
D
Department of Basic Allied Medicine, Kobe University School of Medicine, Kobe, Japan.
Ikeshita
Nobuko
N
Daito
Rie
R
Herningtyas
Elizabeth Henny
EH
Toda
Keizo
K
Takahashi
Kentaro
K
Iida
Keiji
K
Takahashi
Yutaka
Y
Kaji
Hidesuke
H
Chihara
Kazuo
K
Okimura
Yasuhiko
Y
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D004435:Eating / Q000187:drug effects; D054439:Ghrelin; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology; D019382:Human Growth Hormone / Q000097:blood*; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology; D036361:Peptide Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013972:Thyrotropin / Q000097:blood*
D054439:Ghrelin; D009842:Oligopeptides; D036361:Peptide Hormones; C505799:obestatin, human; D019382:Human Growth Hormone; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D013972:Thyrotropin; D013007:Growth Hormone-Releasing Hormone; C091874:growth hormone-releasing peptide-2