Trypanosoma cruzi: Choline acetyltransferase activity in tissues of susceptible and resistant mice infected with the Brazil strain

In order to ascertain if there were biochemical differences in the autonomic nervous system of both C57BL/6-(resistant) and C3H/HeJ-(susceptible) mice infected with the "Brazil" strain of Trypanosoma cruzi we studied the depletion of the enzyme, choline acetyltransferase (EC 2.3.1.6) in the hearts and brains of these infected mice. In the hearts of C3H/HeJ mice, a 30-35% depletion of choline acetyltransferase was evident by day 7 of infection, a time characterized by lack of obvious parasitemia and frank morphological changes in the myocardium or atrial ganglia. When these mice were moribund (day 25) the depletion of choline acetyltransferase was approximately 40%. Myocardial inflammation, necrosis, and increased pseudocyst numbers were evident as the infection proceeded and as the parasitemia rose. In addition, right atrial ganglia were involved with inflammatory cells but were devoid of amastigotes. In resistant (B6) mice choline acetyltransferase levels were not depleted during the course of infection. Brain choline acetyltransferase levels were significantly depleted in moribund C3H mice but there were no frank morphological changes. Extracts of T. cruzi were devoid of any substances capable of inhibiting choline acetyltransferase. Choline acetyltransferase depletion in the hearts of infected susceptible animals precedes morphological alteration. Depletion of this enzyme may be utilized as an early parameter of infection.