ABSTRACT
Brachiaria decumbens and B. brizantha (signal grass), which occupy millions of acres in Brazil, are an important source of fodder for ruminants. Sporadic outbreaks of photosensitization in ruminants grazing on signal grass have been reported. Intoxicated animals showed the presence of foamy cells in the liver, spleen, intestinal submucosa and lymph nodes. These foamy cells are macrophages. They are very difficult to distinguish with haematoxylin and eosin stain, especially in the case of isolated cells. The purpose of the present study was to detect specific carbohydrate residues of storage material in the foamy cells in tissues of cattle exposed to Brachiaria spp. The characterization of glycoconjugates provides clues to the pathogenesis of these cells. Besides, the lectin peanut agglutinin was found to be an excellent marker to differentiate and quantify the foam cells, and could be used as a specific marker.
Subject(s)
Brachiaria/poisoning , Cattle Diseases/pathology , Foam Cells/pathology , Plant Poisoning/veterinary , Animal Feed , Animal Husbandry/methods , Animal Nutritional Physiological Phenomena , Animals , Biomarkers , Brazil , Cattle , Cattle Diseases/immunology , Histocytochemistry/veterinary , Lectins , Liver/pathology , Lymph Nodes/pathology , Macrophages/pathology , Plant Poisoning/immunology , Plant Poisoning/pathologyABSTRACT
Solanum glaucophyllum (Sg) (synonym S. malacoxylon) is a plant toxic to cattle due to its high levels of 1,25-dihydroxyvitamin D3 as glycoside derivatives. Sg causes a disease characterized by wasting and calcification of soft tissues. The effects of vitamin D are not only important in calcium homeostasis, but also in immune regulation, cell growth and cell differentiation. Skin samples in Sg-intoxicated and control heifers were studied histologically. Cellular differentiation and proliferation were analysed by immunohistochemical expression of cytokeratins, involucrin and proliferating cell nuclear antigen (PCNA). The results were obtained by image processing and analysis and were statistically evaluated. Sg-intoxicated cattle showed atrophy of epidermis and severe involution of hair follicles and of sebaceous and sweat glands. As judged by PCNA expression, cellular proliferation was reduced, even though the reduction was not statistically significant. The analysed markers of differentiation, e.g. involucrin and cytokeratins 10 and 11, changed in relation to Sg-poisoning. The possible pathogenesis of the skin lesions is discussed.
