open access

Vol 62, No 4 (2011)
Review article
Published online: 2011-08-30
Submitted: 2013-02-15
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Technological difficulties in ghrelin and obestatin assays

Jerzy Kosowicz, Aleksandra Baumann-Antczak, Hanna Zamysłowska, Jerzy Sowiński
Endokrynologia Polska 2011;62(4):336-339.

open access

Vol 62, No 4 (2011)
Review article
Published online: 2011-08-30
Submitted: 2013-02-15

Abstract

In recent years we have performed more than 1,000 radioimmunoassays of ghrelin and obestatin. In these assays, we have encountered several technological obstacles. Another difficulty was the enormous discrepancy of plasma ghrelin results published by different authors. The aim of this article is to comment on these problems. Not all peptides of the hypothalamus and intestines are present in blood circulation. Several neuropeptides do not cross the blood-brain barrier, and several gastrointestinal peptides are present in extremely low concentrations in the blood. That requires time-consuming and laborious extraction. In these procedures, considerable amounts of peptides may be lost. In addition, these peptides are very unstable and prone to enzymatic degradation. This makes it mandatory to add enzymatic inhibitors to plasma samples. The peptides are also unstable in elevated temperatures, hence the assays should be performed in air-conditioned laboratories and the kits should be transported in proper low temperature conditions. Peptides may appear in several isoforms of different biological activity, but antibodies routinely used in these assays are polyclonal and do not differentiate between these forms. This complicates clinical evaluation of the results. To date, there are no international standards of ghrelin, obestatin or other active peptides, probably because of their extreme instability. Because of technological difficulties, the results of peptide assays performed in different scientific research institutions vary greatly and cannot be compared to each other. This disadvantage may be partially diminished by including samples of healthy subjects in each assay run to check whether the peptide concentrations of the patients differ significantly from that of control subjects.
(Pol J Endocrinol 2011; 62 (4): 336–339)

Abstract

In recent years we have performed more than 1,000 radioimmunoassays of ghrelin and obestatin. In these assays, we have encountered several technological obstacles. Another difficulty was the enormous discrepancy of plasma ghrelin results published by different authors. The aim of this article is to comment on these problems. Not all peptides of the hypothalamus and intestines are present in blood circulation. Several neuropeptides do not cross the blood-brain barrier, and several gastrointestinal peptides are present in extremely low concentrations in the blood. That requires time-consuming and laborious extraction. In these procedures, considerable amounts of peptides may be lost. In addition, these peptides are very unstable and prone to enzymatic degradation. This makes it mandatory to add enzymatic inhibitors to plasma samples. The peptides are also unstable in elevated temperatures, hence the assays should be performed in air-conditioned laboratories and the kits should be transported in proper low temperature conditions. Peptides may appear in several isoforms of different biological activity, but antibodies routinely used in these assays are polyclonal and do not differentiate between these forms. This complicates clinical evaluation of the results. To date, there are no international standards of ghrelin, obestatin or other active peptides, probably because of their extreme instability. Because of technological difficulties, the results of peptide assays performed in different scientific research institutions vary greatly and cannot be compared to each other. This disadvantage may be partially diminished by including samples of healthy subjects in each assay run to check whether the peptide concentrations of the patients differ significantly from that of control subjects.
(Pol J Endocrinol 2011; 62 (4): 336–339)
Get Citation

Keywords

ghrelin; obestatin; assays; technological difficulties

About this article
Title

Technological difficulties in ghrelin and obestatin assays

Journal

Endokrynologia Polska

Issue

Vol 62, No 4 (2011)

Pages

336-339

Published online

2011-08-30

Bibliographic record

Endokrynologia Polska 2011;62(4):336-339.

Keywords

ghrelin
obestatin
assays
technological difficulties

Authors

Jerzy Kosowicz
Aleksandra Baumann-Antczak
Hanna Zamysłowska
Jerzy Sowiński

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