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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.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:tede/844 |
| Date | 31 July 2009 |
| Creators | Nogueira, Vivian de Assun??o |
| Contributors | Peixoto, Paulo Fernando de Vargas, Fran?a, Ticiana do Nascimento, Brito, Marilene de Farias |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Curso de P?s-Gradua??o em Ci?ncias Veterin?rias, UFRRJ, Brasil, Parasitologia Veterin?ria |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
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