Behavioural alterations are independent of sickness behaviour in chronic experimental Chagas disease

The existence of the nervous form of Chagas diseaseis a matter of discussion since Carlos Chagas described neurological disorders, learning and behavioural alterationsin Trypanosoma cruzi-infected individuals. In most patients, the clinical manifestations of the acute phase, including neurological abnormalities, resolve spontaneously without apparent consequence in the chronic phase of infection. However, chronic Chagas diseasepatients have behavioural changes such as psychomotor alterations, attention and memory deficits, and depression. In the present study, we tested whether or not behavioural alterationsare reproducible in experimental models. We show that C57BL/6 mice chronically infected with the Colombian strain of T. cruzi (150 days post-infection) exhibit behavioural changes as (i) depression in the tail suspension and forced swim tests, (ii) anxiety analysed by elevated plus mazeand open field test sand and (iii) motor coordinationin the rotarod test. These alterationsare neither associated with neuromuscular disorders assessed by the grip strengthtest nor with sickness behaviour analysed by temperature variation sand weight loss. Therefore, chronically T. cruzi-infected mice replicate behavioural alterations(depression and anxiety) detected in Chagas diseasepatients opening an opportunity to study the interconnection and the physiopathology of these two biological processes in an infectious scenario.