Effects of phenylbutazone on gene expression of cyclooxygenase-1 and -2 in the oral, glandular gastric, and bladder mucosae of healthy horses.
OBJECTIVE
To assess gene expressions of cyclooxygenase-1 and -2 in oral, glandular gastric, and urinary bladder mucosae and determine the effect of oral administration of phenylbutazone on those gene expressions in horses.


METHODS
12 healthy horses.


METHODS
Horses were allocated to receive phenylbutazone or placebo (6 horses/group); 1 placebo-treated horse with a cystic calculus was subsequently removed from the study, and those data were not analyzed. In each horse, the stomach and urinary bladder were evaluated for ulceration via endoscopy before and after experimental treatment. Oral, glandular gastric, and urinary bladder mucosa biopsy specimens were collected by use of a skin punch biopsy instrument (oral) or transendoscopically (stomach and bladder) before and after administration of phenylbutazone (4.4 mg/kg, p.o., q 12 h) in corn syrup or placebo (corn syrup alone) for 7 days. Cyclooxygenase-1 and -2 gene expressions were determined (via quantitative PCR techniques) in specimens collected before and after the 7-day treatment period and compared within and between groups. Prior to commencement of treatment, biopsy specimens from 7 horses were used to compare gene expressions among tissues.


RESULTS
The cyclooxygenase-1 gene was expressed in all tissues collected. The cyclooxygenase-2 gene was expressed in the glandular gastric and bladder mucosae but not in the oral mucosa. Cyclooxygenase gene expressions were unaffected by phenylbutazone administration.


CONCLUSIONS
Cyclooxygenase-2 was constitutively expressed in glandular gastric and bladder mucosae but not in the oral mucosa of healthy horses. Oral administration of phenylbutazone at the maximum recommended dosage daily for 7 days did not affect cyclooxygenase-1 or -2 gene expression.
Comparative Gastrointestinal Laboratory, Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA 95616, USA. jenieto@ucdavis.edu
Jorge E
JE
Nieto
Monica
M
Aleman
Jonathan D
JD
Anderson
Ciara
C
Fiack
Jack R
JR
Snyder
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology*; D051545:Cyclooxygenase 1 / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D003558:Cystoscopy / Q000662:veterinary; D005260:Female; D005773:Gastroscopy / Q000662:veterinary; D005786:Gene Expression Regulation / Q000187:drug effects*; D006736:Horses / Q000378:metabolism*; D008297:Male; D009055:Mouth / Q000187:drug effects / Q000473:pathology; D009092:Mucous Membrane / Q000187:drug effects* / Q000473:pathology; D010653:Phenylbutazone / Q000008:administration & dosage / Q000494:pharmacology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012333:RNA, Messenger / Q000378:metabolism; D013270:Stomach / Q000187:drug effects / Q000473:pathology; D001743:Urinary Bladder / Q000187:drug effects / Q000473:pathology
D000894:Anti-Inflammatory Agents, Non-Steroidal; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D010653:Phenylbutazone