TACHYKININS STIMULATE LIPID-PEROXIDATION MEDIATED BY FREE-RADICALS INGASTROINTESTINAL-TRACT OF RAT

Tissue concentrations of malondialdehyde in the gastrointestinal tract of the rat were quantified as indicators of lipid peroxidation and ti ssue damage after challenge with tachykinins and after pretreatment wi th allopurinol. Neurokinin A: neurokinin B, and substance P given intr avenously during 30 min increased the production of malondialdehyde in the stomach, duodenum, jejunum, and colon in a dose-dependent manner at doses from 100 to 400 pmol/kg/min (P < 0.05-0.01). However, the sto mach seemed less responsive to the tachykinin challenge. For compariso n, a similar dose-dependent increase of malondialdehyde was found in t he liver and lung, with more pronounced effects of neurokinin B (P < 0 .05-0.01). Pretreatment with allopurinol, 10 mg/kg, significantly redu ced malondialdehyde responses to tachykinin challenge in intestinal ti ssues (P < 0.001). In conclusion, elaboration of malondialdehyde is su ggested to reflect the ability of gastrointestinal tissues to react to tachykinins at high concentrations with liberation of free radicals a s part of an inflammatory reaction.