[Experimental dilatation of the cecum and colon in rats. III. A model induced by prolonged administration of lactose in the diet of animals in the chronic phase of infection by the Y strain of T. cruzi].

Female Wistar albino rats (30 days of age), weighing about 60 g, were inoculated intraperitoneally with 1000 parasites/g of the Y strain of T. cruzi. The strain of T. cruzi has been maintained by in vivo passage of the parasites from mice to mice in the Department of Parasitology, Microbiology and Immunology, Medical School of Ribeirão Preto. Rats of the same sex and age were used as controls. One-hundred 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 ether anesthesia. The volume of the large intestine was measured, and the weight of cecum and colon were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)