PREGANGLIONIC FIBERS OF THE ADRENAL-MEDULLA AND CERVICAL SYMPATHETIC-GANGLIA - DIFFERENTIAL INVOLVEMENT DURING EXPERIMENTAL AMERICAN TRYPANOSOMIASIS IN RATS

The acute phase of experimental Chagas' disease in rats is associated with early lesions of the post-ganglionic sympathetic nerve terminals of the heart, the varicosities being the target. In the superior cervi cal and stellate ganglia the preganglionic fibres showed no signs of l esion in the course of experimental Chagas' disease. In the adrenal me dulla, however, the acute phase of the Trypanosoma cruzi infection ind uced a clear rarefaction of the acetylcholinesterase-positive nerve fi bres (20 and 32 days after infection). Recovery of the normal pattern occurred in most animals by day 125 after infection. At days 20, 32 an d 46 after infection, electron-microscopic studies demonstrated the oc currence of damage in cholinergic nerve terminals contacting the chrom affin cells. The signs of damage included dense bodies, clumps of syna ptic vesicles and filaments, rarefaction of all organelles, vacuoles a nd irregular contour. The ultrastructural peculiarities of the sympath etic ganglia may explain the ganglionar microenvironment protective ag ainst the hazardous factors elicited by acute Chagas' disease.