Determination of the source of increased serotonin (5‐HT) concentrations in blood and peritoneal fluid of colic horses with compromised bowel

Abstract

In horses with compromised bowel, significant amounts of 5-HT can be released into the systemic circulation, through massive release of platelet-stored 5-HT. 5-HT is a very potent proinflammatory, vasoconstrictive and immunomodulatory agent. In view of the rapid and prolonged tachyphylaxia, shown for the jejunal 5-HT1A-like receptors, this increased systemic 5-HT release could play a role in the pathophysiology of ileus in horses.

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

“…A total of 152 platelet-poor ethylenediamine tetraacetic acid (EDTA) plasma samples were prepared according to protocols earlier described. 7,13 Further, 6 activated platelet samples, prepared by adding collagen a (15 µg/ml) to platelet-rich EDTA plasma, and 6 serum samples were collected to obtain a wide range of serotonin concentrations.…”

“…Reported PPP serotonin values in healthy horses range from 2.5 ng/ml to 90 ng/ml with a majority varying between 3 ng/ml and 30 ng/ml. 1,2,4,6,7,13,[17][18][19]21 One possible explanation for this inconsistency is the use of different analytical techniques. Therefore, it is essential to develop fast and reliable detection methods, which are well validated for use on equine plasma samples.…”

“…5,10,21 An association has been found between increased plasma 5-HT concentrations and digital hypoperfusion causing laminitis. [4][5][6]21,22 Other research groups have demonstrated serotonin changes in surgical colic cases, 3,13 recurrent airway obstruction, 17 Cushingoid horses, 18 and other acute or chronic disease states. 3 Serotonin plasma levels are also subject to physiological variations.…”

“…Different methods have been described for serotonin measurement; however, most were developed for human plasma analysis. High-performance liquid chromatography (HPLC) with amperometric detection, 25,32 electrochemical detection, 1,6,30,33,35 coulometric detection, 20,34 and fluorescence detection 13 have been reported. It must be mentioned that none of these methods make use of a more conventional ultraviolet detector, due to the insufficient ultravioletabsorbing capacities of serotonin.…”

Study on bronchoconstriction induced by histamine or serotonin in “Precision Cut Lung Slices” of the horse

“…In the horse, much attention has been paid to the prokinetic effects of serotonin on the gastrointestinal tract (Delesalle et al 2008) and its vasoconstrictive effects in laminitis (Menzies-Gow et al 2008, Zerpa et al 2007), whereas its effects on equine small airways has not been studied ex vivo. The PCLS technique was described by Martin et al (1996) and Wohlsen et al (2001) in mice and human lung tissue.…”