Changes in the mouse sciatic nerve action potential after epineural injection of sera from Trypanosoma cruzi infected mice

Pathology of chronic Chagas' disease involves peripheral nervous system (PNS) compromise. A high prevalence of antibodies reacting with nervous system antigens has been found in the sera of patients and infected animals, although their physiological role in mediating PNS tissue damage is unknown. Here, we demonstrate that epineural injection of sera from Trypanosoma cruzi infected mice affects the characteristics of the sciatic nerve action potential (SNAP) depending on the parasite strain. Sera from mice infected with the reticulotropic/neurotropic RA strain with reactivity against sciatic nerve (RA/Ne+ sera) induced delays on latency and diminished amplitudes 4 days after injection. Sera from mice infected with the myotropic CA-I strain failed to affect SNAP. Purified immunoglobulin (Ig)G from RA/Ne+ also diminished the amplitude of SNAP. Deposits of IgG labelling axonal fibres and/or myelin sheaths were detected in nerves injected with RA/Ne+ sera. No major histological damage or parasite DNA was found in those nerves. The SNAP changes after sera injection were similar to those observed in mice injected with trypomastigotes in the epineurum 17 days before and in chronically infected animals. This investigation suggests that autoantibodies triggered as a consequence of T. cruzi infection are able to mediate, at least in part, the electrophysiological abnormalities observed in PNS during the course of Chagas' disease.