Made available in DSpace on 2016-04-28T20:16:31Z (GMT). No. of bitstreams: 1 2009 - Vivian de Assuncao Nogueira.pdf: 2112872 bytes, checksum: 276e22b789893e783e3b6baa392f3bf0 (MD5) Previous issue date: 2009-07-31 / Funda??o Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Sodium monofluoracetate (MF) was identified, by cromatography, in three of the 12 plants that cause "sudden death" in cattle in Brazil. Among these, Palicourea marcgravii is the most important due to its high toxicity (0.6g/kg), wide distribution, good palatability and cummulative effect. In 1959, D?bereiner & Tokarnia detected in the kidney of cattle poisoned by that plant, hydropic-vacuolar degeneration (HVD) of the distal convoluted uriniferous tubules, a lesion they considered typical for the poisoning. MF inhibits the citrate aconitase enzyme, resulting in blockage of the Krebs Cycle and the production of ATP. The objective of this study was to verify if the ingestion of MF causes the same lesions in the kidney of cattle poisoned by the plants which cause sudden death . This would prove that this substance is responsible for the deaths of animals which ingest these plants. Six cows received orally 0.5 and 1 mg/kg of MF (Sigma Aldrich Co) diluted in 50 mL of distilled water. Clinically the animals presented palpitation, replete jugular vein with positive pulse, abdominal breathing, slight balance loss with sometimes swaying gait, the animals laid down and placed the head on their flank. In the dramatic phase , all the animals fell into lateral decubitus, stretched out the legs, made peddling movements, presented opistotonus, nistagmus, and died. The dramatic phase lasted from 3 to 14 minutes. At postmortem examination, the heart auricles, jugulars and pulmonary veins were moderately ingurgitated. Slight to moderate edema of the subserosa was seen in places of fixation of the gall bladder to the liver, besides slight edema around the duodenum in contact with the pancreas. Histopathology revealed HVD of the epithelial cells of the distal convoluted uriniferous tubules associated with nuclear picnosis in all cows. Coagulation necrosis of individual or groups of hepatocytes and slight hepatic congestion secondary to the venous stasis were also observed. Hydropic-vacuolar degeneration has been observed in cases of poisoning by many substances, which cause acute tubular nephrosis, however not restricted to the distal renal tubules and without nuclear picnosis. This study demonstrates that this peculiar kind of HVD in the kidney can be caused by MF and, in analogy, the compound should be considered responsible for the death of cattle that ingest toxic plants which cause "sudden death" in Brazil. For the first time it has now been proved that MF causes HVD of the distal convoluted uriniferous tubules, what indicates that studies of possible degradation of MF by rumen bacteria could have economic importance, as there die annually at least 600.000 cattle by sudden death causing toxic plants. / Monofluoracetato de s?dio (MF) foi identificado, por cromatografia, em Palicourea marcgravii, Arrabidaea bilabiata e possivelmente em Mascagnia rigida, plantas do grupo das que causam morte s?bita em bovinos no Brasil. Em 1959, D?bereiner & Tokarnia detectaram no rim de bovinos intoxicados por P. marcgravii, uma les?o por eles considerada t?pica para intoxica??o, a degenera??o hidr?pico-vacuolar dos t?bulos urin?feros contorcidos distais (DHV). O modo de a??o do MF baseia-se na inibi??o da enzima citrato aconitase, do que redunda bloqueio do ciclo de Krebs e da produ??o de ATP. O objetivo deste trabalho foi verificar se a ingest?o de MF induz as mesmas les?es observadas no rim de bovinos intoxicados pelas plantas que causam morte s?bita , o que indicaria que essa subst?ncia ? respons?vel pelas mortes dos animais que ingeriram essas plantas. Foram realizados experimentos em que seis vacas receberam, por via oral, 0,5 e 1,0 mg/kg de MF dilu?dos em 50 mL de ?gua destilada. Clinicamente os animais apresentaram taquicardia, jugular repleta com pulso venoso positivo, respira??o abdominal, ligeira perda de equil?brio, por vezes cambaleavam, deitavam e apoiavam a cabe?a no flanco. Na fase dram?tica, todos os animais ca?am em dec?bito lateral, esticavam os membros, faziam movimentos de pedalagem, apresentavam opist?tono, nistagmo, mugidos e morriam. O per?odo da fase dram?tica durou entre 2 e 14 minutos. ? necropsia verificaram-se aur?culas, jugulares, ?zigos e pulmonares moderadamente ingurgitadas. Observaram-se ainda leve a moderado edema da subserosa nos locais de fixa??o da ves?cula biliar no f?gado, al?m de leve edema em torno do intestino delgado (duodeno) em contato com p?ncreas. O exame histopatol?gico revelou, em todos os animais, leve a acentuada DHV das c?lulas epiteliais dos t?bulos urin?feros contorcidos distais associada ? cariopicnose nuclear. Vacuoliza??o e necrose de coagula??o individual ou de grupos de hepat?citos e leve congest?o hep?tica secund?rios ? estase venosa tamb?m foram observados. DHV tem sido observada em casos de envenenamento por outras subst?ncias, por?m esta n?o est? restrita aos t?bulos distais e n?o se observa cariopicnose nuclear. Dessa forma, esse estudo demonstra que a DHV que ocorre no rim de bovinos ? caracter?stica do envenenamento por MF e, por analogia, essa subst?ncia pode ser considerada como um dos fatores importantes, sen?o o mais significativo, implicado no ?bito dos animais que ingerem plantas que causam morte s?bita no Brasil. Comprova-se, pela primeira vez, que o MF induz ? a causa da DHV dos t?bulos uriniferos contorcidos distais, o que indica que estudos que envolvam metaboliza??o de MF por bact?rias ruminais teriam grande aplicabilidade econ?mica, uma vez que pelo menos 600.000 bovinos morrem anualmente intoxicados por plantas do grupo das que causam morte s?bita no Brasil.