Cardiac autonomic denervation and expression of neurotrophins (NGF and BDNF) and their receptors during experimental Chagas disease.

Although cardiac dysautonomia is a distinctive feature of Chagas disease, its clinical and functional significance is still being speculated. Neurotrophic factors are potentially involved; however, studies of their effect in this infection are rare. Ultrastructural abnormalities in autonomic varicosities, levels of both nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF), as well as the expression of their receptors, were analysed in the heart of a rat model of Trypanosoma infection. Predominantly, at the early stage of the infection, cardiac autonomic varicosities displayed several signs of degeneration parallel to the elevation of cardiac levels of NGF, as well as expression of the receptors TrkA and p75NTR. For BDNF and TrkB, the changes were less conspicuous. Data obtained here can contribute to further clarify the factors related to the autonomic nervous system's adaptive changes that could determine the evolution of different clinical forms of Chagas disease; mainly, the cardiac form.