[Experimental dilatation of the cecum and colon in rats. IV. Evaluation of a model produced by the use of lactose in the food of animals in the chronic phase of infection by the Colombia strain of T. cruzi].

Female Wistar albino rats (30 day of age) were inoculated three times in intervals of 7 days with 1 x 10(7) epimastigote forms of T. cruzi and challenged 30 days after the last inoculation with 1 x 10(5) trypomastigote forms of the Colombia strain of T. cruzi. Rats of the same sex and age were used as controls. One-hundred-fifty days after inoculation the animals were allocated into 4 groups: Group I (control), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); Group II (inoculated), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); Group III (control), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks); and Group IV (inoculated), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks). The disaccharide (lactose or saccharose) was added to a standard laboratory diet, 25 g/100 g of the final weight of the diet. At the end of the experimental periods the animals were sacrificed in light ether anesthesia. The volume of the large intestine was measured, and the weights of the cecum and colon were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)