title: Plasma and serum serotonin concentrations and surface-bound platelet serotonin expression in Cavalier King Charles Spaniels with myxomatous mitral valve disease.
abstract: OBJECTIVE
  To investigate serum and plasma serotonin concentrations, percentage of serotonin-positive platelets, level of surface-bound platelet serotonin expression (mean fluorescence intensity [MFI]), and platelet activation (CD62 expression) in platelet-rich plasma from Cavalier King Charles Spaniels with myxomatous mitral valve disease (MMVD).
  
  
  METHODS
  Healthy dogs (n = 15) and dogs with mild MMVD (18), moderate-severe MMVD (19), or severe MMVD with congestive heart failure (CHF; 10).
  
  
  METHODS
  Blood samples were collected from each dog. Serum and plasma serotonin concentrations were measured with an ELISA, and surface-bound platelet serotonin expression and platelet activation were determined by flow cytometry.
  
  
  RESULTS
  Dogs with mild MMVD had higher median serum (746 ng/mL) and plasma (33.3 ng/mL) serotonin concentrations, compared with MMVD-affected dogs with CHF (388 ng/mL and 9.9 ng/mL, respectively), but no other group differences were found. Among disease groups, no differences in surface-bound serotonin expression or platelet activation were found. Thrombocytopenic dogs had lower serum serotonin concentration (482 ng/mL) than nonthrombocytopenic dogs (731 ng/mL). In 26 dogs, a flow cytometry scatterplot subpopulation (FSSP) of platelets was identified; dogs with an FSSP had a higher percentage of serotonin-positive platelets (11.0%), higher level of surface-bound serotonin expression (MFI, 32,068), and higher platelet activation (MFI, 2,363) than did dogs without an FSSP (5.7%, 1,230, and 1,165, respectively). An FSSP was present in 93.8% of thrombocytopenic dogs and in 29.5% of nonthrombocytopenic dogs.
  
  
  CONCLUSIONS
  A substantive influence of circulating serotonin on MMVD stages prior to CHF development in Cavalier King Charles Spaniels was not supported by the study findings. An FSSP of highly activated platelets with pronounced serotonin binding was strongly associated with thrombocytopenia but not MMVD.
authors.forename: Signe E
authors.initials: SE
authors.lastname: Cremer
authors.forename: Annemarie T
authors.initials: AT
authors.lastname: Kristensen
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Reimann
authors.forename: Nynne B
authors.initials: NB
authors.lastname: Eriksen
authors.forename: Stine F
authors.initials: SF
authors.lastname: Petersen
authors.forename: Clara B
authors.initials: CB
authors.lastname: Marschner
authors.forename: Inge
authors.initials: I
authors.lastname: Tarnow
authors.forename: Mark A
authors.initials: MA
authors.lastname: Oyama
authors.forename: Lisbeth H
authors.initials: LH
authors.lastname: Olsen
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D001947:Breeding; D016022:Case-Control Studies; D004283:Dog Diseases / Q000097:blood*; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000150:complications / Q000662:veterinary*; D006349:Heart Valve Diseases / Q000097:blood / Q000150:complications / Q000662:veterinary*; D008297:Male; D008943:Mitral Valve; D015539:Platelet Activation; D053657:Platelet-Rich Plasma / Q000378:metabolism; D012701:Serotonin / Q000097:blood / Q000378:metabolism*
chemical_list: D012701:Serotonin