title: Ghrelin inhibits in vitro angiogenic activity of rat brain microvascular endothelial cells.
abstract: Ghrelin, a 28-amino acid peptide originally isolated from rat stomach, is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R). Evidence has been provided that ghrelin and GHS-Rs are highly expressed in the cardiovascular system, including endothelial cells (ECs), of which they regulate the growth in vitro. It, therefore, seemed worthwhile to investigate the effect of ghrelin on in vitro angiogenesis, using cultures of rat ECs derived from brain microvessels (neuromicrovascular ECs, NECs). ECs, when cultured on a supportive matrix, form a network of tubule-like structures, and such process is enhanced by the classic angiogenic factors, including fibroblast growth factor-2 (FGF-2). After seeding on Matrigel-coated wells, NECs formed within 18 h a meshwork of capillary-like structures; vinblastine (2 x 10(-12) M) disrupted the meshwork, while FGF-2 (50 ng/ml) increased its density. Ghrelin (10(-8) M) exerted a vinblastine-like effect and counteracted the stimulatory action of FGF-2. Computerized image-analysis confirmed these observations. FGF-2 enhanced the proliferation rate and lowered the apoptotic rate of NECs cultured on plastic wells, and ghrelin exerted opposite effects and completely reversed the proliferogenic and antiapoptotic actions of FGF-2. In contrast to vinblastine, ghrelin did not increase lactate dehydrogenase release from cultured NECs, thereby ruling out the possibility that its effects may ensue from an aspecific cytotoxic action. FGF-2 enhanced tyrosine kinase (TK) and mitogen activated protein kinase (MAPK) p42/p44 activities of NECs. Ghrelin significantly decreased TK and MAPK p42/p44 activities and effectively counteracted the effect of FGF-2. Taken together, the present findings indicate that ghrelin exerts a marked in vitro antiangiogenic action, and that the mechanism underlying this effect involves the inhibition of TK/MAPK-dependent cascades.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, University of Padua, I-35121 Padua, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Baiguera
authors.forename: Maria Terresa
authors.initials: MT
authors.lastname: Conconi
authors.forename: Diego
authors.initials: D
authors.lastname: Guidolin
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Mazzocchi
authors.forename: Ludwik K
authors.initials: LK
authors.lastname: Malendowicz
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Parnigotto
authors.forename: Raffaella
authors.initials: R
authors.lastname: Spinazzi
authors.forename: Gastone G
authors.initials: GG
authors.lastname: Nussdorfer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D054439:Ghrelin; D008297:Male; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D036361:Peptide Hormones / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones