The objective was to study the secretory pattern, both basal and stimulated either by histamine (0.1 mg/kg) or pentagastrin (64 ug/kg) in eighteen Cebus apella monkeys chronically infected with different T. cruzi strains (CA1, n=10; Colombian, n=4 and Tulahuen, n=4) and to describe the morphological findings in the gastrointestinal tract in twelve infected (6 sacrificed and 6 spontaneously dead) and four healthy monkeys. All infected monkeys and 35 healthy ones were evaluated by contrast X-ray examination. No differences were observed in basal acid output between control and infected groups. Animals infected with the Tulahuen and Colombian strains showed significant lower values of peak acid output in response to histamine or pentagastrin (p<0.01 and p<0.05 respectively; "t" test) in comparison to the controls. Barium contrast studies showed enlargement and dilatation of the colon in three infected animals. Histopathological lesions were seen in 75% of the autopsied animals either in colon alone (33%) or both, in colon and esophagus (42%). The normal secretion observed in the CA1 infected group could be due to a lower virulence of the strain, a lower esophagic tropism or the necessity of a longer post-infection time to cause lesions.

El objetivo fue estudiar la respuesta secretora basal y estimulada por histamina (0.1 mg/kg) o pentagastrina (64 ug/kg) en 18 monos Cebus apella cronicamente infectados con diferentes cepas de T. cruzi (CA1 n=10; Colombiana n=4 y Tulahuén n=4). Además se describieron los hallazgos morfológicos en el tracto gastrointestinal de 12 animales muertos (6 sacrificados y 6 espontaneamente). Se evaluó radiológicamente el tracto gastrointestinal de 35 Cebus sp. sanos (controles) y 18 infectados crónicamente. Se estudiaron histopatologicamente 4 controles y 12 infectados. No hubo diferencias en la secreción basal ácida entre los grupos control e infectado. Los animales infectados con la cepa Tulahuén y Colombian tuvieron valores más bajos en el pico de secreción ácida, como respuesta a la histamina o a la pentagastrina (p<0.01 y p<0.05 respectivamente; test "t") con respecto a los controles. Los estudios con contraste de bario mostraron agrandamiento y dilatación del colon en 3 animales infectados. En las autopsias de los chagásicos se encontraron lesiones histologicas en el 75% de los casos (solo en colon, 33%; en colon y esofago, 42%). En el grupo CA1, la secreción ácida estuvo dentro de los parámetros normales y esto se podría deber a una baja virulencia de la cepa, a un menor tropismo esofágico o a que el tiempo post-infección fue demasiado corto para causar lesiones.

Dezoito macacos Cebus apella (jovens e adultos de ambos os sexos) foram inoculados há 5 anos atrás, com 3 cepas de T. cruzi (CA1, n = 10; Colombiana, n =4 e Tulahuen, n =4) seja por via conjuntival ou intraperitonial, uma única vez ou repetidamente. Os achados parasitológicos, hematológicos, sorológicos, enzimáticos, radiográficos, eletro e ecocardiográficos foram anteriormente publicados15 e são semelhantes àqueles vistos no homem. O achado eletrocardiográfico mais freqüente foi o bloqueio do ramo direito. Seis animais, escolhidos ao acaso, foram sacrificados. Aqueles sacrificados 20 a 25 meses após a primeira inoculação mostraram acúmulos focais de leucócitos com miocitólise. Focos de fibrose intersticial difusa com pequeno infiltrado de leucócitos entre as fibras foram observados em animais sacrificados 36 a 47 meses após a inoculação. Não foram encontrados parasitas. As lesões foram mais proeminentes nas paredes ventriculares e no septo. O achado de infiltrados predominantemente, nos animais sacrificados em tempo mais curto em relação à primeira inoculação e a fibrose mais severa naqueles sacrificados após um tempo maior sugere que existe uma progressão das lesões infiltrativas até a fibrose, com atividade leucocítica indicativa de fase crônica. Estas lesões são semelhantes àquelas descritas na doença de Chagas crônica humana. Este modelo, portanto, é útil na avaliação do progresso e conhecimento da patogênese da doença, assim como de sua imunologia, imunogenesis e da ação da quimioterapia, tanto na sua fase crônica como indeterminada.

Eighteen Cebus apella monkeys, (juvenile and adult of both sexes) were inoculated five years ago, with three Trypanosoma cruzi strains (CA1, n = 10; Colombian, n=4 and Tulahuen, n=4), either by conjunctival or intraperitoneal route, once or repeatedly. Parasitological, hematological, serological, enzymatic, radiographic, electro and echocardiographic findings have been peviously published15 and they are similar to those observed in human pathology. The most frequent electrocardiographic alteration was right branch bundle block. Six animals, chosen at random, were sacrificed. Those sacrificed 20 to 25 months post-first inoculation showed focal accumuli of leukocytes with myocytolysis. Foci of diffuse interstitial fibrosis with mild infiltrate of leukocytes among fibers were observed in the animals sacrificed 36 to 47 months post-inoculation. No parasites were seen. The lesions were more prominent in the ventricular walls and the septum. The fact that the infiltrates were predominant in the animals sacrificed at a shorter time after first inoculation and that fibrosis was more severe in those sacrificed at a longer time suggests that there is a progression of the infiltrative lesions to fibrosis, with a leukocytic activity indicative of a chronic phase. These lesions are similar to those described in human chronic Chagas' disease. This would demonstrate that this model is useful in evaluating a progress in the knowledge of the pathogenesis which is still a controversial issue, immunology, immunogenesis and chemotherapeutic agents of the chronic and indeterminate phases of this disease.