RESUMO.-[Eliminação da toxina tremorgênica de
INTRODUCTIONIpomoea asarifolia R. et Schult. (common name: salsa), family Convolvulaceae, is a plant native to South and Central America. In Brazil it is very common in the Amazon region, in the Northeast, and along the coast, from northern Brazil to the southern states of Rio de Janeiro and São Paulo (Kissmann & Groth 1992). I. asarifolia is a tremorgenic plant that causes poisoning in sheep (Döbereiner et al. 1960, Guedes et al. 2007), goats (Döbereiner et al. 1960, Medeiros et al. 2003, Guedes et al. 2007), cattle (Döbereiner et al. 1960, Barbosa et al. 2005) and buffalo (Barbosa et al. 2005). Clinical signs caused by I. asarifolia are similar than those caused by the indole-diterpene mycotoxins produced by different fungi (di Menna et al. 2012, Cawdell-Smith et al. 2010, but the tremorgenic toxin of the plant is unknown.In With the aim to determine if the tremorgenic toxin of Ipomoea asarifolia is eliminated in milk, three groups of Swiss female mice received, immediately after giving birth until weaning, a ration containing 20% or 30% of dry I. asarifolia. All the offspring of the females that received 20% or 30% I. asarifolia showed tremors 2-4 days after birth. The offspring of the females that received 20% I. asarifolia recovered 4-7 days after weaning. The offspring of the females that received 30% of the plant in the ration died while showing tremors before weaning or up to two days after weaning. It is concluded that the tremorgenic compound of I. asarifolia or its toxic metabolites are eliminated in milk, and that lactating mice may be used as a model for the determination of the toxic compound(s) in this plant.
Milk is a complex emulsion of lipids suspended in aqueous protein solution that can be a carrier of various contaminants, but generally it is not an important route of toxic excretion. The main problem is chronic repetitive exposure, as it occurs with ingestion of toxic plants and its potential danger to animals that consume the milk. Previously reported hazardous phytotoxins eliminated by milk include: indolizidine alkaloids, causing oligosaccharide storage disease; piperidine alkaloids, causing acute poisoning or malformations; pyrrolizidine alkaloids, which cause hepatic lesions; quinolizidine alkaloids, as a cause of skeletal defects; glucosinolates, which cause changes in the thyroid; tremetol (or tremetone), which causes a disease characterized by tremors in animals and milk sickness in humans; sodium monofluoracetate, which causes the death of kids after ingestion of colostrum from goats that have ingested Amorimia septentrionalis during gestation; ptaquiloside, which induces carcinogenesis in animals that ingest milk or derivatives produced by animals that have ingested Pteridium spp. Ipomoea asarifolia, which contains indole diterpenes causing tremors in suckling pups. Chrysocoma ciliata causes alopecia in suckling pups, but its toxic compound is still unknown. Knowledge about the risk of exposure to these substances via milk and its dissemination are important for veterinary and human health.
In Brazil is estimated that poisoning of livestock by sodium monofluoroacetate (MFA) containing plants causes the death of about 500.000 cattle per year. The ruminal inoculation of bacteria that degrade MFA has been proposed as a way to prevent the poisoning. This study aimed to evaluate in goats resistance to the MFA-containing plant Amorimia septentrionalis induced by ruminal inoculation of the bacteria Pigmentiphaga kullae and Ancylobacter dichloromethanicus. Twelve goats, without previous contact with MFA-containing plants, were divided into two groups of six animals each. In group 1, 60ml of a mixture of the two bacteria was inoculated every day for 10 days into each goat. In group 2, the goats did not receive the bacteria. At the 10th day of inoculation, A. septentrionalis began to be administered daily at a dose of 5g/kg body weight to both groups. The administration was interrupted in each goat after first clinical signs of poisoning were observed.. The goats of group 1 showed clinical signs 5.83±2.56 days after the administration of the plant, what differed significantly (p=0.037) from goats of group 2, that showed clinical signs 2.67±0 52 days after the beginning of ingestion. The amount of A. septentrionalis ingested by inoculated goats (28.83±12.97g/kg) to cause clinical sings was significantly greater (p=0.025) than the amount ingested by the non-inoculated (12.03±3.65) goats to cause clinical signs and was also statistically different between the groups. We concluded that the intraruminal administration of Pigmentiphaga kullae and Ancylobacter dichloromethanicus increases the resistance to poisoning by MFA-containing plants.
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