L. Cuzzolin et al., ROLE OF ENDOGENOUS AND EXOGENOUS NITRIC-OXIDE ON INTESTINAL-MUCOSA AND MICROFLORA IN THE RAT, Inflammation, 21(4), 1997, pp. 443-450
In the present study the effects of exogenous and endogenous nitric ox
ide (NO) on intestinal bacteria and on the intestinal tissue integrity
have been investigated in healthy rats and in rats receiving bacteria
l endotoxin (LPS). A segment of jejunum was taken in order to evaluate
tissue damage and hematoxylin-eosin staining; microbiological studies
were carried out collecting stool samples. Administration of LPS (5 m
g kg(-1) i.v.) induced a moderate jejunal damage, which was completely
prevented by N-G-nitro-L-arginine methyl ester (L-NAME, 5 mg kg(-1) s
.c.), thus suggesting a damage of endogenous NO on the intestinal muco
sa; sodium nitroprusside (SNP, 10 mg kg(-1) os) reduced significantly
jejunal damage induced by LPS. Endogenous NO produced by the administr
ation of LPS resulted to be cytotoxic for all examined aerobic and ana
erobic bacteria, while exogenous NO, released from SNP, showed an inhi
bitory effect only on Entero. faecalis and E coli growth. From our dat
a, it seems reasonable to conclude that high local levels of NO are re
quired in order to observe jejunal damage and cytotoxic effects on aer
obic and anaerobic faecal flora.