Doença do armazenamento lisossomal induzida por Sida planicaulis Cav. (Malvaceae) em ovinos no Estado do Rio de Janeiro

Abstract

This paper describes an outbreak of lysosomal storage disease in sheep induced by Sida planicaulis in the state of Rio de Janeiro. The consumption of S. planicaulis is responsible for this disease in cattle, horses, goat, sheep and captive deer, which occurs naturally, when the plant is abundant and there is shortage of other forage. The main toxic compound in this plant, Swainsonine, inhibits α-manosidasis I e II enzymatic activitiy and causes glycoprotein storage in lysosomes. The storage provokes compression, deficiency in intracytoplasmatic transport, and finally, degenerative changes in various tissues, in which, nervous system is the most affected. Physical examination of the affected animals revealed proprioceptive déficit, motor incoordination, staggers and, neck and head intention tremors. ‘Head-Raising Test’ showed marked increase of head and limb tremors, with sequential difficulty in balance and tumble. Histopathology revealed severe distension of Purkinje cells, with foamy appearance, which eventually progressed to karyolysis and pyknosis, and intense vacuolization of pancreatic acinar and thyroid follicular cells. Additionally, there was vacuolization in neuronal bodies with dissolution of cytoplasm associated with marked proliferation of morphologically atypical astrocytes. Multiple axonal spheroids of variable sizes were noted. Positive reaction in lectin-histochemistry for lectins Con A, WGA, and sWGA was able to characterize the disease as a glycoproteinosis. Ultrastructural evaluation of pancreas sections evidenced numerous vacuoles up to 2,5μm in diameter, circled by 20nm wide membranes in acinar cells. In the present report, diagnosis of S. planicaulis toxicosis was established by epidemiological data, clinical and pathological findings, and confirmed by lectin-histochemistry and ultrastructural evaluation. Natural toxicosis in sheep by Sida planicaulis has not yet been described in the state of Rio de Janeiro.