title: Effects of ghrelin on growth hormone secretion from cultured adenohypophysial cells in cattle.
abstract: To clarify the direct effects of ghrelin on growth hormone (GH) release from anterior pituitary (AP) cells in cattle, GH-releasing effects of human ghrelin (hGhrelin) and rat ghrelin (rGhrelin) on bovine AP cells were compared with those of GH-releasing hormone (GHRH) in vitro. The AP cells were obtained from Holstein steers and were incubated for 2 h with the peptides after incubating in DMEM for 3 days. hGhrelin and rGhrelin significantly stimulated GH release from the cultured cells at doses from 10(-10) to 10(-7) M and from 10(-9) to 10(-7) M, respectively (P<0.05). The rates of increase in GH at 10(-10), 10(-9), 10(-8) and 10(-7) M hGhrelin were 26, 26, 59 and 100% compared with controls, respectively, and those of increase in GH at 10(-9), 10(-8) and 10(-7) M rGhrelin were 58, 74 and 106%, respectively. GHRH significantly increased GH concentrations in cultured media at a dose as low as 10(-13) M compared with the control (P<0.05). When hGhrelin (10(-8) M) and GHRH (10(-8) M) were added together, the release of GH induced by both peptides was significantly greater than that by hGhrelin alone (P<0.05), and tended to be greater than that by GHRH alone. Somatostatin (SS, 10(-7) M) significantly blunted GH release induced by hGhrelin (10(-8) M) and GHRH (10(-8) M) (P<0.05). In the presence of SS, the percent increase in GH released with hGhrelin plus GHRH was 42% and 14% greater than that by either hGhrelin or GHRH alone, respectively (P<0.05). These results show that ghrelin directly stimulates the release of GH from anterior pituitary cells, and that SS modifies ghrelin-stimulated GH release in cattle.
authors.affiliation: Faculty of Agriculture, Iwate University, Ueda 3, Morioka 020-8550, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hashizume
authors.forename: Mami
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Naomi
authors.initials: N
authors.lastname: Tate
authors.forename: Sumie
authors.initials: S
authors.lastname: Nonaka
authors.forename: Masayasu
authors.initials: M
authors.lastname: Kojima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosoda
authors.forename: Kenji
authors.initials: K
authors.lastname: Kangawa
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D054439:Ghrelin; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D036361:Peptide Hormones / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D013004:Somatostatin / Q000378:metabolism*
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones; D013004:Somatostatin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone