The role of nitric oxide in aloe-induced diarrhoea in the rat.
The role of nitric oxide (NO) on aloe-induced diarrhoea was studied in the rat. Nine hours after oral administration, aloe produced diarrhoea at doses of 5 g kg(-1)(20% rats with diarrhoea) and 20 g kg(-1) (100% of rats with diarrhoea). Lower doses of aloe (0.1 and 1 g kg(-1) did not produce a diarrhoeal response. Pre-treatment (i.p.) of rats with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME 2.5-25 mg kg(-1) reduced the diarrhoea induced by aloe (20 g kg(-1) 9 h after its oral administration. L-NAME (25 mg kg(-1)) also reduced the increase in faecal water excretion produced by aloe (20 g kg(-1). L-arginine (1500 mg kg(-1), i.p.), administered to rats pre-treated with L-NAME (25 mg kg(-1), drastically reduced the effect of L-NAME on diarrhoea and increase in faecal water excretion induced by aloe (20 g kg(-1). Given alone, L-arginine did not modify aloe-induced diarrhoea. Basal Ca2+ -dependent NO synthase activity in the rat colon was dose-dependently inhibited by aloe (0.1-20 g kg(-1)) and by aloin (0.1-1 g kg(-1)), the active ingredient of aloe. These results suggest that endogenous NO modulates the diarrhoeal effect of aloe.
Izzo
A A
AA
Department of Experimental Pharmacology, University of Naples Federico II, Italy.
Sautebin
L
L
Borrelli
F
F
Longo
R
R
Capasso
F
F
D000504:Aloe / Q000009:adverse effects*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001834:Body Water / Q000187:drug effects / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D003672:Defecation / Q000187:drug effects; D003967:Diarrhea / Q000139:chemically induced / Q000503:physiopathology* / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005243:Feces / Q000737:chemistry; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010946:Plants, Medicinal; D051381:Rats; D017208:Rats, Wistar; D019323:omega-N-Methylarginine / Q000494:pharmacology
D002614:Chelating Agents; D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D004533:Egtazic Acid; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester