Preservação seletiva de neurônios mioentéricos nitrérgicos em modelo de infecção experimental crônica pelo Trypanosoma cruzi (megacólon)

Abstract

Chagas disease is the important neglected tropical disease and in Latin America, considered endemic, it presents infectivity estimated 5.7 million people in 21 countries. The overall annual cost of health care is of the order of 627 million dollars due to disabilities related to high morbidity. The disease progresses chronically with changes in the enteric nervous system which have been associated with the development of esophageal achalasia and /or megacolon. The role of nitric oxide derived from intestinal inflammatory disorders in neurons has been investigated, but there are no studies in mice in models with chronic Chagas' disease. This work aimed to study the impact of inflammation and denervation induced by Y strain of Trypanosoma cruzi in mice. We use functional and structural markers such as PGP expression 9.5 (gene protein product 9.5) and nNOS (synthase neuronal nitric oxide) and Sub P rec (substance P receptor), ChAT (choline acetyltransferase) and VIP (vasoactive intestinal polypeptide) in neurons of the myenteric plexus in the acute and chronic phases of the experimental disease. For this purpose, consecutive sections of colon uninfected and infected mice in the acute and chronic phases were marked by PGP 9.5 and nNOS by immunohistochemistry (IHC) and assessed for morphology by light microscopy. Photographic documentation of slides was performed and the images analyzed. It was also performed RT-PCR on frozen samples to analyze expression of VIP, nNOS, ChAT and Substance P receptor. Our results demonstrate a reduction in the total number of neurons marked for PGP 9.5 in the chronic phase in infected mice compared to the controls. The immunohistochemically expressed nNOS positive neurons in the acute phase remained unchanged, while in the chronic phase, the inhibitory nitrergic neurons appeared increased. The nNOS protein expression by RT-PCR remains constant in groups in both phases. To the marker of excitatory neurons (Substance P), the expression by RT-PCR was significantly decreased in chronic phase with the control. Despite the need for additional analysis, our data suggest a reduction of excitatory neurons, while nitrergic neurons seem preserved, which contributes to the understanding of functional changes that characterize the megacolon.