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P009. The changes of the NO-ergic system, arginase and oxidative processes in the muscular layer of the colon under the conditions of stress and experimental colitis

V. Yemelyanenko1, O. Sklyarov1, 1Danylo Halytsky Lviv National Medical University, Biochemistry, Lviv, Ukraine

Background

Stress affects the function of the digestive organs, causing alterations of the motility, secretion, microcirculation, membranes permeability and biocenosis. Both stress and colitis cause the decrease of the motor-evacuating function of the colon, alterations of the digestion, water and electrolytes transport. Nitric oxide is assumed to play the key role in the mechanisms of the dilatation of the smooth muscles of the colon.

Methods

Aim of the study was to evaluate the changes of the enzymes of NO-synthases system, lipid peroxidation, antioxidant defense enzymes and nitrite anion content in the muscular layer of the colon (MLC) and L-arginine concentration in plasma in experimental colitis and stress. The studies were conducted on 38 white male rats. Stress was induced by epinephrine 2 mg/kg intraperitoneally. Colitis was induced by 1 ml 4% acetic acid intrarectally. One of the groups of experimental animals was exposed both to stress and colitis. 24 hours later the rats were sacrificed and NO-synthases (NOS) and arginase activity, nitrite anion content, lipid peroxidation and antioxidant enzymes activity in MLC were assessed and L-arginine concentration in plasma.

Results

In control animals the activity of constitutive NOS (cNOS) in MLC was dominating, whereas inducible NOS (iNOS) activity was low. Epinephrine-induced stress caused 5-fold rise of iNOS activity, 30% increase of cNOS, 26% increase of nitrite anion and 39% increase of MDA content in MLC, whereas L-arginine concentration in plasma decreased for 40%. Arginase activity decreased for 40% in MLC. The development of colitis caused 5.9-fold rise of iNOS, 49% rise of cNOS, 33% increase of nitrite anion and 55% rise of MDA in MLC and 41% decrease of L-arginine concentration in plasma. Arginase activity in MLC had tendancy to decrease.

The effect of epinephrine-induced stress in colitis caused 24% increase of iNOS, compared to colitis, whereas nitrite anion and MDA level and arginase activity coincided with the level of these indices in colitis.

Conclusion

The increase of the area of the colonic damage in stress and colitis is accompanied by increase of iNOS and lipid peroxidation, whereas arginase activity decreases. iNOS activity is colitis is superior to that in stress. The exposure of the animals, suffering from colitis, to stress increases iNOS activity.