Tumor necrosis factor-alpha regulates inducible nitric oxide synthase gene expression in the portal hypertensive gastric mucosa of the rat.
Increased expression of both nitric oxide synthase (NOS) and tumor necrosis factor-alpha (TNF-alpha) have been implicated in the hyperdynamic circulation of portal hypertension. Since overexpression of these proteins would affect gastric mucosal defenses, which are impaired in portal hypertension, we examined the expression and interrelationships of TNF-alpha and NOS in the gastric mucosa of portal hypertensive rats. Following staged portal vein ligation, gastric strips from portal hypertensive rats were incubated in organ culture medium with or without TNF-alpha antibody. The expression of TNF-alpha and NOS mRNAs was assessed by reverse transcription-polymerase chain reaction (RT-PCR) at baseline and after 1, 2, and 6 hours of incubation. RT-PCR demonstrated a threefold increase in inducible NOS mRNA and a 50% increase in TNF-alpha mRNA expression at baseline in portal hypertensive animals as compared to sham-operated animals. In tissue incubated with TNF-alpha neutralizing antibody, inducible NOS mRNA expression was significantly decreased by 40%, 70%, and 80% after 1, 2, and 6 hours, respectively. Since increased TNF-alpha and NOS production could potentially impair gastric mucosal defenses, our findings suggest a major role for these proteins in the development of portal hypertensive gastropathy.
Kaviani
A
A
Department of Surgery, Department of Veterans Affairs Medical Center, Long Beach, Calif, USA.
Ohta
M
M
Itani
R
R
Sander
F
F
Tarnawski
A S
AS
Sarfeh
I J
IJ
D000818:Animals; D005753:Gastric Mucosa / Q000201:enzymology*; D005786:Gene Expression Regulation; D006975:Hypertension, Portal / Q000201:enzymology* / Q000235:genetics; D008297:Male; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III