Alterations of the myenteric plexus of the ileum and the descending colon caused by Toxoplasma gondii (genotype III)

Abstract

-Alterations caused by a genotype III strain of Toxoplasma gondii were assessed with respect to the number and the morphometry of the myenteric neurons in the terminal ileum and the descending colon. Eighteen rats were divided into four groups: Acute Control Group (ACG, n=4); Acute Experimental Group (AEG, n=4); Chronic Control Group (CCG, n=5) and Chronic Experimental Group (CEG, n=5). NaCl solution was administered through gavage to the animals in the ACG and CCG. Toxoplasma gondii tachyzoites (10 4 ) from a genotype III strain were orally administered to the AEG and CEG. Acute Groups were died after 24 hours, and the Chronic Groups after 30 days. Neuronal loss was not observed in both organs. The neurons atrophied in the terminal ileum as the opposite occurred with the neurons at the descending colon during the chronic phase of infection. In the terminal ileum, the neurons atrophied during the chronic phase of the infection as no alteration was found during the acute phase. For the descending colon, the neurons became hypertrophic during the chronic infection in opposition to the atrophy found during the acute phase.KEY WORDS: enteric nervous system, toxoplasmosis, morphology. Alterações do plexo mientérico do íleo e cólon descendente causadas por Toxoplasma gondii (genótipo III)Resumo -Objetivou-se avaliar as alterações causadas por uma cepa genótipo III de Toxoplasma gondii, sobre o número e a morfometria de neurônios mientéricos, do íleo terminal e do cólon descendente. Dividiuse dezoitos ratos em quatro grupos: controle agudo (GCA, n=4), experimental agudo (GEA, n=4), controle crônico (GCC, n=5) e experimental crônico (GEC, n=5). Os animais do GCA e GCC receberam solução de NaCl por gavagem, e os animais do GEA e GEC 10 4 taquizoítos de uma cepa genótipo III de T. gondii por via oral. Os grupos agudos após 24 horas foram mortos e os crônicos após 30 dias. Observou-se que não houve perda neuronal em ambos os órgãos. No íleo terminal, os neurônios atrofiaram-se na fase crônica da infecção, enquanto nenhuma alteração ocorreu na fase aguda. Já no cólon descendente, os neurônios tornaram-se hipertróficos na fase crônica da infecção, em oposição à atrofia observada na fase aguda. PALAVRAS-CHAVE: sistema nervoso entérico, toxoplasmose, morfologia.

Effects of infection with Toxoplasma gondii oocysts on the intestinal wall and the myenteric plexus of chicken (Gallus gallus)

“…It is known that IFN-ã and nitric oxide (NO) are among the mediators involved on the infection with protozoans and that they may induce to morphological and quantitative changes of the enteric neurons (Arantes et al 2004). Former studies with rats orally infected with tachyzoites from a Genotype III T. gondii strain demonstrated that there was neither diarrhea nor neuronal death during chronic or acute infection, different from what was observed in this experiment (Sugauara et al 2008). As this has been an exploratory study, new studies are necessary to clarify whether the neurons were lost of partially redistributed as well as which neuronal subpopulation was mostly impaired.…”

“…Plastic changes secondary to the functional changes of the enteric neurons may occurs as a response to the infectious and inflammatory processes (Barbara & Giorgio 2004). Preliminary studies with rats orally infected with tachyzoites from a Genotype III T. gondii strain during 30 days demonstrated that the neurons of the small intestine also presented atrophy (Sugauara et al 2008). One possible explanation for the atrophy and reduction of the neuronal density observed would be that the neurons are dying by the apoptosis as nuclear and cellular atrophy observed in this case may be induced by immunological factors (Pollard 2006).…”

InfecÇão crônica por Toxoplasma gondii induzindo hipertrofia de neurônios do plexo mientérico do cólon descendente de Rattus norvegicus

“…Porém, mantiveram-se inalterados os demais parâmetros morfométricos avaliados, resultados semelhantes aos encontrados em estudos prévios com a infecção crônica com taquizoítos de T. gondii do genótipo III, que levou a um aumento da área do pericário, núcleo e citoplasma dos neurônios do cólon descendente (SUGAUARA et al, 2008). Infecções agudas causadas por cepa do genótipo II não induziram a alterações morfométricas nos neurônios do cólon descendente de ratos, fato atribuído à ausência de tempo para causar uma resposta inflamatória proliferativa (SUGAUARA et al, 2009).…”

Trypanosoma cruzi (CEPA CL) Promove Perda Neuronal no Plexo Mioentérico do Cólon de Ratos

“…A expressão do polipeptídeo intestinal vasoativo ( VIP), da substância P (SP) e do neuropeptídeo Y (NY ) é alterada nos nervos entéricos do jejuno de coelhos durante a infecção com um nematódeo Trichinella spiralis (ARCISZEWSKI et al, 2009). Os neurônios do plexo mioentérico do intestino delgado sofreram atrofia geral com uma redução da área do pericário e do núcleo em aves (BONAPAZ et al, 2010) e em ratos (SUGAUARA et al, 2008) na infecção crônica com Toxoplasma gondii.…”