Experimentally Induced Cholangiohepatopathy by Dosing Sheep with Fractionated Extracts from Brachiaria Decumbens

Abstract

Abstract. Cholangiohepatopathy was induced in 5 lambs by oral administration of extracts from signal grass (Brachiaria decumbens) in Brazil. Grossly there were pale foci multifocally distributed throughout the hepatic parenchyma in 4 lambs. The microscopic changes, which were similar to those produced by other steroidal sapogenins-containing plants such as Tribulus terrestris and Panicum spp., included multifocal cholangitis, bile duct proliferation, and the presence of crystals in the biliary system. Sporadic outbreaks of photosensitization in ruminants grazing on signal grass (Brachiaria decumbens) have been reported. 9,21 Cases of photosensitization occurring on this grass in Brazil had formerly been ascribed to intoxication by sporidesmin from spores of the saprophytic fungus Pithomyces chartarum. 2,7,8 However, the potential importance of steroidal saponins present in B. decumbens has been established, suggesting that photosensitization by this grass belongs to the group of plant-induced hepatogenous photosensitizations, 9,21 which are also induced by Panicum spp., 3,10,19 Tribulus terrestris, 11,16 Agave lecheguilla, 4 and Narthecium ossifragum. 17 All of these plants contain steroidal saponins and have been associated with cholangitis and deposition of crystals in the biliary system, causing photosensitization in sheep. Furthermore, steroidal sapogenins have been isolated from bile and biliary crystals of sheep fed those plants. 4,10,16,17 The plant saponins are converted by ruminal metabolism into ␤-D-glucuronides of sapogenins, which in the presence of calcium may precipitate, forming the characteristic biliary crystals. 14,21 Diosgenin and yamogenin have been detected from B. decumbens samples and from a mixture of metabolites in the rumen of sheep grazed on B. decumbens. 6,12,14,20 The arguments against involvement of P. chartarum in most Brazilian outbreaks include the low density or even absence of spores and the failure of most fungal isolates to produce sporidesmin. 5,6,[13][14][15]21 Typical photosensitivity has been reproduced in sheep grazing pure pastures of B. decumbens with no detected P. chartarum spores. 6 The aim of the present study was to reproduce hepatic lesions and photosensitization in sheep by oral administration of fractionated extracts from B. decumbens, as has been done with T. terrestris, 11,16 A. lecheguilla, 18 and N. ossifragum. 1 Counts of P. chartarum spores 15 were performed on pasture samples of plant material used for extraction. Forty kilograms of air-dried samples of B. decumbens were powdered and extracted by maceration, using 80 liters ethanol for 7 days at room temperature. A second maceration was performed, and the extracts were mixed. The solvent was evaporated, and the residual alcoholic phase was suspended in water and partitioned with dichloromethane, yielding the dichloromethane and aqueous fractions. After concentration in vacuum and at low temperature (Ͻ55 C), those fractions resulted in 500 g and 1.6 kg of syrupy residues, respectively, which corresponde...

Intoxicação natural por Brachiaria spp. em ovinos no Brasil Central

“…Santos Jr (2008) demonstrou experimentalmente a intoxicação de ovinos jovens pela forrageira entre 7 e 60 dias após serem introduzidos nas pastagens. Cruz et al (2001), também de forma experimental, demonstraram a intoxicação de um animal, entre nove ovinos, 89 dias após a introdução do grupo em piquete de Brachiaria decumbens.…”

“…em ruminantes (Salam Abdullah et al 1988, Graydon et al 1991, Lemos et al 1998, Lemos & Purisco 2002, Riet-Correa & Mendez 2007, Rissi et al 2007), porém foi visualizada em somente 13,3% dos animais avaliados nesse estudo. Acredita-se que a causa da icterícia seja a obstrução de vias biliares pelos cristais formados pela conjugação das saponinas presente nas espécies de braquiária (Cruz et al 2000(Cruz et al , 2001. Essa obstrução provoca colestase, diminuição da excreção de pigmentos biliares e outros metabólitos promovendo o amarelamento de tecidos e órgãos (Santos 2000).…”

Spontaneous poisoning by Brachiaria decumbens in goats

“…Icterus was frequently observed in other outbreaks in goats (Abas-Mazniet al 1985, Opasina 1985, Lemos et al 1998. The cause of icterus in this disease is an obstruction of the bile ducts by crystals formed by aggregation of saponins, characterizing a post-hepatic icterus (Cruz et al 2001). At necropsy of animals had shown clinical signs of weight loss and dehydration there were emaciation, marked serous atrophy of the fat storage and varying degrees of cavity edema.…”

Fall Panicum (Panicum dichotomiflorum) Hepatotoxicosis in Horses and Sheep

“…Either an endophyte or its toxic metabolite could be present intermittently and could be partially or solely responsible for the toxicosis. Although several authors have induced hepatogenous photosensitization with steroidal saponin extracts or plants deemed free of mycotoxins, 8,[10][11]14 other work has demonstrated that similar disease can be induced with the mycotoxin sporidesmin. 9 Thus, some researchers postulate that a synergy between plant saponins and other hepatotoxins, particularly mycotoxins, may explain the sporadic incidence of hepatic disease.…”

“…1 However, several reports document hepatogenous photosensitization or hepatopathies in grazing animals after ingestion of various Panicum, 2-6 Brachiaria, 7,8 Tribulus, 9,10 and Narthecium 11 grass species. These plants contain steroidal saponins, 4,8,[10][11][12][13][14][15] and affected ruminants often develop bile crystals composed of the calcium salts of steroidal saponin glucuronides. [16][17][18][19][20] Only 2 reports 6,15 describe hepatotoxicosis in horses after consumption of these grass species.…”