ABSTRACT.-Costa S.Z.R., Peixoto P.V., Brust L.A.C., d' Avila M.S., Santos A.M., Driemeier D., Nogueira V. A. & França T.N. 2016. [Troponin C in the immunohistochemistry detection of early regressive changes in sheep myocardium naturally poisoned by Amaranthus spinosus (Amaranthaceae).] Troponina C na detecção imuno-histoquímica de alterações regressivas precoces no miocárdio de ovinos naturalmente intoxicados por Amaranthus spinosus (Amaranthaceae). Pesquisa Veterinária Brasileira 36(2):83-89. Curso de Pós-Graduação em Medicina Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, BR-465 Km 7, Seropédica, RJ 23890-000, Brazil. E-mail: samayzillmann@gmail.com Amaranthus spp. are nephrotoxic plants popularly known as "pigweed". In cases of poisoning by these plants, the main histopathological alteration is found in the kidneys as toxic tubular nephrosis; however, in some cases, there may be cardiac changes. ECG changes associated with hyperkalemia have been described in pigs poisoned by Amaranthus retroflexus. Degeneration and necrosis of myocytes have been described in pigs poisoned by A. caudatus and sheep poisoned by A. spinosus. There are doubts regarding cardiac changes, since in most cases they are incipient and don't exhibit inflammatory reaction, which can lead to misinterpretation. For this study, paraffin blocks with tissues from a poisoning outbreak by A. spinosus in southeastern Brazil were used. The objective of the study was to detect the presence of incipient regressive changes in the myocardium of sheep poisoned by A. spinosus using anti-troponin C antibody-based immunohistochemistry. Fragments of hearts from 8 adult sheep and 2 fetuses naturally poisoned by A. spinosus were used. In the immunohistochemistry evaluation of the 8 hearts from the adult sheep there were several groups of myocytes with significant decrease or absence of immunoreactivity for anti-troponin C antibody. In most cases, these same areas on Hematoxylin and Eosin (HE) staining exhibited changes that varied from mild cellular tumefaction to increased eosinophilia, as well as loss of striation, cell lysis and karyolysis, sometimes accompanied by inflammatory infiltrate. In four cases, it was possible to notice that several small groups of myocytes exhibited decreased immunoreactivity corresponding to cells with undetectable or very subtle alterations on HE staining. The hearts of both fetuses did not exhibit areas with loss or decreased immunoreactivity for the anti-troponin C antibody. The results of this immunohistochemical evaluation confirmed the presence of incipient regressive changes and confirmed the occurrence of well-established necrotic lesions in the myocardium of sheep poisoned by Amaranthus spinosus. There was correspondence between areas where immunostaining for troponin was absent and areas with the most marked lesions obser-1 Recebido em 24 de julho de 2015Aceito para publicação em 28 de novembro de 2015 Parte da Tese de Doutorado do primeiro autor.

RESUMO Este trabalho tem por objetivo descrever um caso de carcinoma espinocelular da base do chifre, bilateral e simétrico, em uma vaca e discutir a questão hormonal, possivelmente envolvida na patogênese da doença. Tratava-se de uma fêmea bovina, 11 anos, com histórico de emagrecimento progressivo, presença de massas exofíticas na base de ambos os chifres e em anestro por muitos anos. Foi realizada biopsia incisional de ambas as lesões para exame histopatológico e dosagens hormonais. Devido à progressão do quadro clínico, optou-se pela eutanásia, seguida dos exames necroscópico e histopatológico. O exame histopatológico revelou tratar-se de um carcinoma espinocelular infiltrativo bem diferenciado, e as dosagens hormonais apresentaram alterações nos níveis do hormônio luteinizante, folículo estimulante e estrógenos totais. Apesar de existirem descrições de carcinomas espinocelulares da base do chifre, ainda não havia relatos da ocorrência do mesmo bilateral e em uma vaca com distúrbios hormonais.