RESUMEN
The aim of this study was to investigate the influences of ovariectomy on histopathological and hematological parameters during the course of Trypanosoma cruzi infection. Hematological and immunological homeostasis is influenced by gonadal steroid hormones. Ovariectomy exerts profound influences on parasitic diseases including T. cruzi infection through modulation of the host's immune response. Three groups of female Mus musculus were infected with 4000 blood trypomastigotes of the Y strain of T. cruzi. One group was subjected to ovariectomy, another to simulated surgery before the infection, and a third group of unoperated animals were used as controls. Marked differences were detected in the responses of blood and tissue parasites. On day 9, post-infection parasitism was significantly higher in ovariectomized animals (P<0.05). These results were confirmed by histopathological studies, in which ovariectomized animals displayed hearts with higher number of amastigote burdens, increased inflammatory infiltrate, enhanced tissue fibers disorganization and decreased lytic antibody percentage, when compared to their counterparts. On day 9 the hematological changes were more apparent, with a decrease in erythrocytes, platelets and leucocytes for ovariectomized infected animals. Simulated surgery, as a stressful agent, did not cause any imbalance in parasitism or in the hemogram profile. The results confirm the importance of the female steroids in resistance against T. cruzi infection.