Efeitos da infecção crônica por Toxoplasma gondii no comportamento do tipo depressivo em camundongos expostos a uma condição de estresse crônico

Abstract

Toxoplasma gondii (T. gondii) is an obligatory intracellular parasite that infects approximately one-third of the global human population, serving as the etiological agent of toxoplasmosis. Numerous studies have demonstrated its capacity to infect a diverse range of species, establishing latent infections in the brain and implicating its role in the pathogenesis of various psychiatric disorders, including schizophrenia, anxiety, obsessive-compulsive disorder, impulsivity disorders, and depression. The present study sought to investigate whether chronically infected mice with T. gondii, subjected to a chronic stress condition through movement restriction, displayed altered behavior. BALB/c mice were categorized into four groups based on the following criteria: a.) control: without stress and without chronic T. gondii infection; b.) stressed: animals subjected to stress without chronic T. gondii infection; c.) infected: animals without stress but with chronic T. gondii infection; d.) infected/stressed: animals experiencing both stress and chronic T. gondii infection. The impact on mice subjected to chronic T. gondii infection revealed an increase in depressive-like behavior compared to groups under stressed or non-stressed conditions, as well as to the both groups of uninfected animals. Notably, the immobility time of infected mice was higher, and they spent less time swimming than the groups of uninfected animals. No significant differences were observed in anti-T. gondii levels or parasite load in the brains of both groups of infected mice. Furthermore, akin to the group of stressed animals alone, the infected/stressed animals exhibited lower body weight gain compared to the control or only infected groups. In conclusion, our findings unveil new perspectives on understanding the consequences of T. gondii chronic infection, specifically in the presence of parasite cysts within the central nervous system.