Abstract
Ghrelin, the only known peripherally produced and centrally acting peptide that stimulates food intake, is synthesized primarily in the stomach and acts through the growth hormone secretagogue receptor (GHS-R1a). In addition to its orexigenic effect, ghrelin stimulates the release of growth hormone (GH). In this study, we investigated the biological properties of full-length and shortened ghrelin analogs in which octanoylated Ser3 is replaced with an octanoic acid moiety coupled to diaminopropionic acid (Dpr). Ghrelin analogs stabilized with Dpr(N-octanoyl) in position 3 and noncoded amino acids in position 1 (sarcosine) and/or position 4 (naphthylalanine or cyclohexylalanine) were found to possess affinities similar to those of ghrelin for cell membranes with transfected GHS-R1a. In vivo, the prolonged orexigenic effects of analogs containing Dpr(N-octanoyl)3 compared with that of ghrelin in adult mice and a similar impact on GH secretion in young mice were found. Full-length [Dpr(N-octanoyl)3]ghrelin and its analogs with a noncoded amino acid in position 1 and/or 4 showed significantly prolonged stability in blood plasma compared with that of ghrelin. Ghrelin analogs with a prolonged orexigenic effect are potential treatments for GH deficiency or cachexia that accompanies chronic diseases. Desoctanoylated ghrelin analogs and N-terminal penta- and octapeptides of ghrelin did not show any biological activity.
Footnotes
This work was supported by the Grant Agency of the Czech Republic [Grant 303/09/0744]; and the Academy of Sciences of the Czech Republic [Grant Z40550506].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
-
ABBREVIATIONS:
- GH
- growth hormone
- Cha
- cyclohexylalanine
- Dpr
- diaminopropionic acid
- ghr
- ghrelin
- GHS-R1a
- growth hormone secretagogue receptor
- LC-MS
- liquid chromatography-mass spectrometry
- Nal
- naphthylalanine, Sar sarcosine.
- Received June 22, 2011.
- Accepted December 16, 2011.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|