Plasma serotonin in horses undergoing surgery for small intestinal colic.

This study compared serotonin concentrations in platelet poor plasma (PPP) from healthy horses and horses with surgical small intestinal (SI) colic, and evaluated their association with postoperative ileus, strangulation and non-survival. Plasma samples (with EDTA) from 33 horses with surgical SI colic were collected at several pre- and post-operative time points. Serotonin concentrations were determined using liquid-chromatography tandem mass spectrometry. Results were compared with those for 24 healthy control animals. The serotonin concentrations in PPP were significantly lower (P < 0.01) in pre- and post-operative samples from surgical SI colic horses compared to controls. However, no association with postoperative ileus or non-survival could be demonstrated at any time point. In this clinical study, plasma serotonin was not a suitable prognostic factor in horses with SI surgical colic.

Sérotonine plasmatique chez des chevaux subissant une chirurgie pour des coliques du petit intestin. Cette étude a comparé les concentrations de sérotonine dans le plasma faible en plaquettes (PFP) de chevaux en santé et de chevaux atteints de coliques chirurgicales du petit intestin et a évalué leur association avec l'occlusion intestinale postopératoire, la strangulation et la non-survie. Des échantillons de plasma (avec EDTA) ont été prélevés auprès de 33 chevaux atteints de coliques du petit intestin à plusieurs moments préopératoires et postopératoires. Les concentrations de sérotonine ont été déterminées à l'aide d'un spectromètre de masse LC-ESI-MS/MS. Les résultats ont été comparés avec ceux de 24 animaux témoins en santé. Les concentrations de sérotonine du PFP étaient significativement inférieures (P < 0,01) dans les échantillons préopératoires et postopératoires provenant des chevaux atteints de coliques du petit intestin comparativement aux animaux témoins. Cependant, aucune association avec l'occlusion intestinale postopératoire ou la non-survie n'a pu être démontrée à aucun moment. Dans cette étude clinique, la sérotonine plasmatique ne s'est pas avéré un facteur de pronostic approprié chez les chevaux atteints de coliques chirurgicales du petit intestin.(Traduit par Isabelle Vallières).

Comparative analysis of serotonin in equine plasma with liquid chromatography--tandem mass spectrometry and enzyme-linked immunosorbent assay.

Serotonin is regularly measured in equine platelet-poor plasma in research settings. However, reported reference values vary between studies, partially because plasma serotonin concentrations are very low and a reliable and affordable detection method is lacking. A simple, rapid, and sensitive method for serotonin determination in equine platelet-poor plasma using liquid chromatography--tandem mass spectrometry (LC-MS/MS) was developed and validated. Results of a commercially available enzyme-linked immunosorbent assay (ELISA) were compared to the LC-MS/MS results, in order to validate a test more suitable for use in a clinical situation. For LC-MS/MS, 500 µl of plasma was required, and deuterated serotonin was used as an internal standard. The sample preparation was based upon a simple liquid extraction into ethyl acetate. Chromatographic separation was performed with an acetic acid--acetonitrile mobile phase gradient elution. Linearity was demonstrated between 3 ng/ml and 100 ng/ml. A limit of quantification of 3 ng/ml was achieved, corresponding to a limit of detection of 0.10 ng/ml. Comparison of LC-MS/MS and ELISA with Passing-Bablok regression and Bland--Altman plotting showed a poor agreement between the 2 methods, with an increasing difference within the higher range of measurements. Caution is needed when extrapolating results from sources using different analytical techniques.