Intoxicação espontânea e experimental por Brachiaria radicans (tanner-grass) em bovinos / Natural and experimental poisoning by Brachiaria radicans (tanner grass) in cattle

Brachiaria radicans (tanner-grass,) cresce bem em solos úmidos. Em Santa Catarina é encontrada principalmente nas regiões dos vales dos rios Tubarão e Itajaí. Quando ingerida em grandes quantidades pelos bovinos induz anemia hemolítica, hemoglobinúria, diarreia e pode evoluir para a morte. O objetivo deste trabalho foi avaliar os dados epidemiológicos e clínico-patológicos causados por B. radicans em bovinos. A planta foi administrada a 12 bovinos em doses de 50-100 por cento da dieta. Os animais que receberam uma dieta que consistia de 100 por cento da planta, originária de solos turfosos, mostraram hemoglobinúria, diarreia, mucosas vermelho-escuras e recuperação após suspensão da ingestão da planta. Exames de sangue e urina revelaram anemia, hemoglobinúria e proteinúria. A histopatologia de material coletado de bovinos que morreram pela doença espontânea, revelou necrose hepática coagulativa e paracentral e nefrose hemoglobinúrica. B. radicans mostrou ser tóxica para bovinos somente quando cresce em solos férteis e se consistir de 100 por cento da dieta.

Brachiaria radicans is a grass that grows well on humid soils. In Santa Catarina, it is found mainly in the valleys of the Tubarão and Itajaí rivers. When eaten by cattle in large amounts induces hemolytic anemia, hemoglobinuria, diarrhea and even death. The objective of this study was to evaluate epidemiologic, clinical and pathological data of the intoxication caused by B. radicans in cattle. The plant was administered to 12 cattle in doses of 50-100 percent of the diet. The animals that received 100 percent of B. radicans, grown on peaty soils, showed hemoglobinuria, diarrhea and dark red mucous membranes; they recovered when ingestion of the grass was discontinued. Blood and urine tests revealed anemia, hemoglobinuria and proteinuria. Histopathology of organs collected from cattle that died from spontaneous poisoning revealed hepatic centrolobular and paracentralr coagulative necrosis and hemoglobinuric nephrosis. B. radicans proved toxic for cattle only when it grows on fertile soils and is ingested as 100 percent of the diet.

Role of melatonin against oxidative tissue damage induced by Cleistanthus collinus in rat brain.

Background & objectives: The leaves of Cleistanthus collinus, an extremely poisonous plant are consumed for suicidal purposes in various parts of India. The mortality rate is high and there is no antidote. In this study, we attempted to delineate oxidative stress as a possible mechanism of action of C. collinus toxicity in rats and the role of melatonin against injury to brain and heart caused by C. collinus. Methods: Adult Wistar rats (130 -200 g, n = 6 per group) of either sex were used. C. collinus at 8 mg/kg body weight (LD50) was administered orally followed by melatonin 15 mg/kg body weight ip or cysteine 500 mg/kg body weight ip (standard) after 2 h. Malondialdehyde (MDA), reduced glutathione (GSH), glutathione peroxidase and catalase levels in brain, heart and blood were estimated and histopathological examinations (brain and heart) were done. For the survival study, rats were treated with increasing doses of melatonin (5, 10 and 15 mg/kg body weight ip) following a lethal dose of C. collinus (10.5 g/kg body weight orally). Results: The results showed a significant (P<0.05) increase in blood and brain MDA levels and decrease in tissue GSH in the LD50 group. This was accompanied by marked gliosis, spongiform necrosis and lymphocytic inflammatory infiltrates in brain and marked congestion, inflammation and muscle necrosis in heart. Melatonin significantly (P<0.05) reduced lipid peroxidation and reversed the histopathological changes induced by C. collinus in the brain but not in the heart. Interpretation & conclusion: Our results suggest that oxidative mechanisms play an important role in C. collinus induced tissue damage and melatonin, by balancing oxidant-antioxidant status ameliorates oxidative organ injury in brain due to C. collinus toxicity.