Toxoplasma gondii infection causes structural changes in the jejunum of rats infected with different inoculum doses.

AIM: To evaluate the mucosal tunic and submucosal plexus of the jejunum of rats infected with different inoculum doses of Toxoplasma gondii.

MAIN METHODS: Rats were infected with different inoculum doses (50, 500, 1000 and 5000 oocysts) of the T. gondii for 30days, while a control group (CG) received saline solution. Blood and feces were collected before euthanasia for analysis of blood and fecal leukocytes (LEs). Histological analysis of the mucosa, submucosa, villi, crypts and enterocytes were performed. Goblet cells, intraepithelial lymphocytes (IELs) and Paneth cells were quantified. Immunohistochemistry was used to assess enteroendocrine serotonergic (5HT-IR) cells, proliferative cells (PCNA+ ) and mast cells. Whole mounts were obtained to determine the total submucosal neurons by Giemsa staining and metabolically active neurons (NADH-d+ ), nitrergic neurons (NADPH-d+ ) and glial cells (S100).

KEY FINDINGS: An increase in blood LEs was observed 30days post-infection (dpi). Fecal LEs were more abundant in the feces in all infected groups at 21 dpi when compared to the CG. The number of IELs, sulfomucin-producing goblet cells, Paneth cells, PCNA+ cells and mast cells increased, whereas the number of 5HT-IR cells decreased. The jejunal architecture was altered, with atrophy of the mucosa, submucosa, villi and crypts. The number of total submucosal neurons decreased, but the NADPH-d+ subpopulation increased.

SIGNIFICANCE: The results show how chronic toxoplasmic infection affects the tissue and cellular composition of the rat jejunum. These structural changes tend to intensify with the inoculum dose, demonstrating the importance of the parasitic load on intestinal alterations.