Developmental changes in cyclooxygenase mRNA expression in the gastric mucosa of rats.
BACKGROUND
In newborn rats, gastric mucosa is more susceptible to various damaging agents and recovers from injury more quickly than in older animals. To determine whether metabolism of prostaglandins is responsible for this mucosal protective mechanism in developing rats, we studied cyclooxygenase (COX) mRNA expression in the mucosa using quantitative real-time polymerase chain reaction (PRC).


METHODS
Cyclooxygenase-1 and COX-2 mRNA was extracted from the gastric mucosa of rats of various ages and quantitatively analyzed using real-time PCR with dual-labeled fluorogenic probes. The copy numbers of cDNA for COX-1 and COX-2 were standardized to glyceraldehyde-3-phosphate dehydrogenase from the same sample.


RESULTS
Cyclooxygenase-1 mRNA expression was lowest in 1-week-old rats and highest in 4-week-old rats. Mucosal damage produced by 150 mmol/L HCl and 60% ethyl alcohol did not increase COX-1 mRNA expression in any age group. Cyclooxygenase-2 mRNA expression increased significantly with age. Mucosal injury increased COX-2 mRNA in each age group, especially in 1-week-old rats. Intraperitoneal lipopolysaccharide also increased COX-2 mRNA in both 1- and 4-week old rats.


CONCLUSIONS
The high level of COX-2 mRNA expression in the gastric mucosa of 1-week-old rats may be responsible for the physiologic characteristics of gastric mucosal defenses in this age group.
Tomomasa
Takeshi
T
Department of Pediatrics, Gunma University School of Medicine, Maebashi, Japan. tomomasa@showa.gunma-u.ac.jp
Ogawa
Tetsushi
T
Hikima
Akio
A
Tabata
Masahiko
M
Kaneko
Hiroaki
H
Morikawa
Akihiro
A
D000367:Age Factors; D000375:Aging / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D005753:Gastric Mucosa / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins; D016133:Polymerase Chain Reaction; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat