Vol 62, No 4 (2011)
Review paper
Published online: 2011-08-30
Technological difficulties in ghrelin and obestatin assays
Endokrynol Pol 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)
(Pol J Endocrinol 2011; 62 (4): 336–339)
Keywords: ghrelinobestatinassaystechnological difficulties
![](https://journals.viamedica.pl/plugins/generic/popups/images/icons/close.png)