Distribution of mRNA coding for 5-hydroxytryptamine receptor subtypes in the intestines of healthy dairy cows and dairy cows with cecal dilatation-dislocation.
OBJECTIVE
To investigate the distribution of mRNA coding for 7 subtypes of 5-hydroxytryptamine receptors (5-HTRs) in the intestines of healthy dairy cows and dairy cows with cecal dilatation-dislocation (CDD).


METHODS
Full-thickness intestinal wall biopsy specimens were obtained from the ileum, cecum, proximal loop of the ascending colon, and external loop of the spiral colon (ELSC) of 15 cows with CDD (group 1) and 15 healthy dairy cows allocated to 2 control groups (specimens collected during routine laparotomy [group 2] or after cows were slaughtered [group 3]).


METHODS
Amounts of mRNA coding for 7 subtypes of 5-HTRs (5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, and 5-HT4) were measured by quantitative real-time reverse transcriptase-PCR assay. Results were expressed as the percentage of mRNA expression of a housekeeping gene.


RESULTS
Expression of mRNA coding for 5-HTR1B, 5-HTR2B, and 5-HTR4 was significantly lower in cows with CDD than in healthy cows. For 5-HTR2B and 5-HTR4, significant differences between cows with CDD and control cows were most pronounced for the ELSC. Expression of mRNA for 5-HTR1D, 5-HTR1F, and 5-HTR2A was extremely low in all groups, and mRNA for 5-HTR1A was not detected.


CONCLUSIONS
Relative concentrations of mRNA coding for 5-HTR1B, 5-HT2B, and 5-HTR4 were significantly lower in the intestines of cows with CDD than in the intestines of healthy dairy cows, especially for 5-HT2B and 5-HTR4 in the ELSC. This supports the hypothesis that serotonergic mechanisms, primarily in the spiral colon, are implicated in the pathogenesis of CDD.
Engel
Ladina
L
Clinic for Ruminants, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Berne, Bremgartenstrasse 109a, PO Box 8466, 3001 Berne, Switzerland.
Kobel
Barbara
B
Ontsouka
Edgar C
EC
Graber
Hans U
HU
Blum
Jürg W
JW
Steiner
Adrian
A
Meylan
Mireille
M
D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism*; D002429:Cecal Diseases / Q000378:metabolism / Q000662:veterinary*; D004108:Dilatation, Pathologic / Q000662:veterinary; D005260:Female; D014644:Genetic Variation; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000601:surgery; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary
D020033:Protein Isoforms; D012333:RNA, Messenger; D011985:Receptors, Serotonin; C078730:serotonin 5 receptor