Distribuição das enzimas NADPH-Diaforase e Tirosina Hidroxilase na substância negra de camundongos infectados pelo Toxoplasma gondii

Abstract

Toxoplasma gondii is a worldwide intracellular protozoan parasite and an important cause of disease in both humans and domestic animals. In Brazil, up to 80% of the population may be infected, depending on the region. Acute infection is generally asymptomatic, with posterior development of tissues cysts located mostly in muscles, retina and the central nervous system. The latent infection can alter behavior in animals and provoke psychotic symptoms in humans. Studies suggest that this infection may contribute to the occurrence of both schizophrenia and Parkinson’s disease, which are associated with abnormalities of the dopaminergic system. In this study we evaluated immunoreactivity for tyrosine hydroxylase (TH) and NADPH-diaphorase activities in the substantia nigra of infected male swiss mice. The animals were inoculated with bradyzoites (10 cysts) from a Toxoplasma gondii (Me-49 strain). The brains were removed after 30 and 60 days, sectioned and submitted to protocols to reveal NADPH-diaforase activity and immunohistochemistry anti-TH. The densitometric analysis showed a lower reactivity to NADPH-diaforase in the substantia nigra of infected animals when comparated with non-infected controls. A similar reduction was also observed in immunoreactivity against TH in the substantia nigra. These results indicate that T. gondii may change the dopaminergic system in infected brains.