FUNCTIONAL-CHANGES OF THE SCIATIC-NERVE I N MICE CHRONICALLY INFECTEDWITH TRYPANOSOMA-CRUZI

The role of short chain fatty acids (SCFA) in murine colonic carcinoge nesis (MCC) has not yet been clarified. In rats, Freeman et al4 have r eported an increased number of colonic tumors induced with dimethylhyd razine (DMH) and sodium butyrate in drinking water. On the other hand, Deschner et al1 showed that tributyrin intake did not increase MCC in duced with azoxymethane. Both of them have reported high levels of fec al butyric acid with sodium butyrate and tributyrin intake. Although s alt intake has been positively associated with colorectal cancer12 som e authors do not support this association6. We have evaluated the infl uence of right hemicolectomy (RH) (right colon as main source of SCFA) and the intake of 2% - pH 7 sodium butyrate (S.BUT) and 4 g/l sodium chloride (S.CHL) in drinking water, in MCC. Forty eight male Wistar ra ts weighing 150 g were divided into 4 groups: RH, S.BUT, S.CHL, contro l (C). Half of the animals received weekly DMH 20 mg/kg subcutaneously for 12 weeks. Necropsy was performed after 6 months. We have determin ed fecal SCFA content by gas chromatography. Neoplasm was present in 7 0% of rats treated with DMH. The number of animals with tumors was: RH 4/6, S.BUT 4/6, S.CHL 3/5, C 6/6. Tumor frequency was: RH 1,17 +/- 0, 48, S.BUT 1,50 +/- 0,76, S.CHL 1,20 +/- 0,49, C 1,50 +/- 0,22. S.BUT g roup, treated with DMH, presented a lower butyric acid concentration ( p < 0,05) in comparison with other groups. We have no explanation for this finding; gastric absorption of sodium butyrate may be an importan t factor. In conclusion: S.BUT, S.CHL intake in drinking water and RH non significantly reduced colonic carcinogenesis in this animal model.