Horm Metab Res 2004; 36(9): 654
DOI: 10.1055/s-2004-825938
Letter to the Editor
© Georg Thieme Verlag KG Stuttgart · New York

Active Ghrelin Levels in Women with Polycystic Ovary Syndrome

S.  Ferrero1
  • 1Department of Obstetrics and Gynaecology · San Martino Hospital · University of Genoa · Genoa · Italy
Further Information

Publication History

Received 19 July 2004

Accepted without revision 18 August 2004

Publication Date:
15 October 2004 (online)

Re: Wasko R, Komarowska H, Warenik-Szymankiewicz A, Sowinski J. Elevated ghrelin plasma levels in patients with polycystic ovary syndrome. Horm Metab Res 2004; 36 : 170 - 173.

An interesting study on ghrelin plasma levels in patients with polycystic ovary syndrome (PCOS) was recently published by Wasko et al. [1]. I would like to point out some observations that may improve our understanding of ghrelin’s role in women with PCOS.

Ghrelin is a 28-amino acid peptide with a unique serine residue at the third position (Ser3); posttranslational esterification with octanoic acid of this residue is essential for binding to type 1a growth hormone secretagogue receptor and subsequent ghrelin biological activity, such as GH release from the pituitary gland [2].

The polyclonal antibody used by the authors (Phoenix Pharmaceutical, Belmont, CA, USA) does not distinguish octanoylated and non-octanoylated ghrelin. Importantly, non-octanoylated ghrelin does not activate type 1a growth hormone secretagogue receptor [3] [4] and is presumed to be inactive [2]. Therefore, the authors measured the total ghrelin levels in women with PCOS, but they could not evaluate the levels of active ghrelin; this limit in their study is particularly relevant, as non-octanoylated ghrelin is far more abundant than active octanoylated ghrelin [3].

Interestingly, Linco Research (St Charles, MO, USA) produces an antibody that is specific for the biologically active form of ghrelin with the octanoyl group on serine 3 (cat. no. GHRA-88HK). The active ghrelin form is very unstable and labile in plasma due to the nature of the octanoyl group on serine-3; as a consequence, special precautions must be taken. In particular, the samples should be kept on ice and processed as quickly as possible after blood is withdrawn. In addition, plasma acidification is recommended.

Measuring both total and biologically active ghrelin concentrations may improve our understanding of the role of this hormone in women with PCOS.

References

S. Ferrero

Department of Obstetrics and Gynaecology · San Martino Hospital · University of Genoa

Largo R. Benzi 1 · 16132 Genoa · Italy

Phone: +39 10511525 or +39 3477211682

Fax: +39 010511525

Email: simone.ferrero@fastwebnet.it