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Determination of the source of increased serotonin (5‐HT) concentrations in blood and peritoneal fluid of colic horses with compromised bowel
Author(s) -
DELESALLE C.,
WALLE G. R.,
NOLTEN C.,
DONCK L.,
HEMELRIJCK A.,
DRINKENBURG W.,
BOSSCHERE H.,
CLAES P.,
DEPREZ P.,
LEFERE L.,
TORFS S.,
LEFEBVRE R. A.
Publication year - 2008
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.2746/042516408x293583
Subject(s) - laminitis , medicine , peritoneal fluid , pathophysiology , horse , platelet activation , jejunum , platelet factor 4 , gastroenterology , serotonin , endocrinology , platelet , receptor , biology , paleontology
Summary Reasons for performing study : Increased plasma (5‐HT) concentrations are reported in horses predisposed to develop laminitis and after i.v. infusion of endotoxins. In the equine jejunum contractile 5‐HT 1A ‐like receptors show tachyphylaxia upon prolonged activation with 5‐HT. Therefore, increased systemic 5‐HT release in colic horses could play a possible role in the pathophysiology of ileus. Objective : To investigate possible increased systemic release of 5‐HT in colic horses with compromised bowel and to identify the source of 5‐HT overload. Methods : Concentrations of 5‐HT were determined in plasma and peritoneal fluid (PF) of healthy horses (n = 10), strangulating small intestinal colic horses (n = 18), nonsurgical colic horses (n = 10) and cryptorchid stallions (n = 6). It was attempted to identify the source of 5‐HT overload by comparing the blood and PF 5‐HT concentrations within horses and by assessing the in vivo platelet activation through determination of the β‐thromboglobulin (β‐TG)/platelet factor 4 (PF4) ratio. Results : All horses in the strangulating small intestinal colic group had plasma (P = 0.006) and PF (P = 0.01) 5‐HT concentrations above those found in the control group. Plasma β‐TG/PF4 ratio in these horses exceeded 2 in all cases, indicating in vivo platelet activation. Concentrations of 5‐HT in PF of colic horses with compromised bowel were significantly lower than the corresponding plasma concentrations (P = 0.005). Potential relevance : 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‐HT 1A ‐like receptors, this increased systemic 5‐HT release could play a role in the pathophysiology of ileus in horses.