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Acta sci. vet. (Impr.); 41: Pub. 1155, 2013. graf

Artigo em Inglês | VETINDEX | ID: biblio-1371111

Resumo

Background: The cholinergic system is involved in many biological functions in mammals and is associated with pathogenesis of infectious diseases, as has participation in transmission of nerve impulses in cholinergic synapses, haematopoiesis, regulation of inflammatory markers, production and coordination of movement, and memory. Rangelia vitalii is a parasite endemic to south of Brazil. This parasite multiplies in the blood and can be visualized in plasma in its free form and/or within leukocytes and erythrocytes, causing various pathologies. Therefore, the purpose of this study was to investigate the activity of cholinergic system enzymes in dogs experimentally infected with R. vitalii. Materials, Methods & Results: Twelve dogs were used, divided into two groups: control group (n = 5), consisting of healthy animals, and infected group with R. vitalii (n = 7). Fresh blood samples of these infected animals were inoculated in seven dogs (2 mL/dog through the jugular vein). Blood samples were collected on days 0, 10 and 20 post-infection (PI). Butyrylcholinesterase (BChE) activity was measured in serum and acetylcholinesterase (AChE) in lymphocytes and whole blood. Boold samples were diluted 1:50 (v/v) in lysis solution (0.1 mmol/L potassium/sodium phosphate buffer containing 0.03% Triton X-100) and frozen (-20 ºC by 7 days) to determine AChE activity in whole blood. Lymphocytes were also obtained from whole blood with EDTA by gradient separation using Ficoll-Histopaque™ plus to AChE activity this cell. After analysis of the samples, was observed that the dogs infected with R. vitalii presented a signifi cant (P < 0.01) increase in AChE activity in whole blood on days 10 and 20 PI. However, the infected group showed a reduced activity in AChE in lymphocytes (P < 0.01) and BChE in serum (P < 0.05) on day 20 PI. Discussion: According to the literature, infected dogs R. vitalii develop regenerative anemia evidenced by an increase in the erytroid precursors in bone marrow associated with alterations of leucogram as leukopenia, neutropenia, eosinopenia, lymphocytosis and monocytosis. Furthermore, it was observed severe thrombocytopenia, with alteration in platelet aggregation and activity of enzymes involved in the control of ATP, ADP and adenosine levels on platelets, thereby influencing hemostasis and contributing to the typical bleeding disease. AChE activity in whole blood was increased in dogs parasitized by R. vitalii observed in this study. This increase may be a compensatory effect to severe anemia caused by the parasite infection, because this enzyme is involved in the maturation of erythrocytes and in the regulation of hematopoiesis. In the present study, we found that the reduction in AChE activity in lymphocytes is associated to lymphocytosis; and it is known that ACh is produced within lymphocytes and has the ability to negatively modulate the immune response, acting directly on the inhibition of inflammatory mediators. Therefore, the decrease of AChE activity may have an anti-inflammatory action in order to have more free ACh to bind lymphocytes and inhibit inflammation. The enzyme BChE can also act as an inflammatory marker in various diseases, similar to AChE, because the enzyme can hydrolyze acetylcholine when AChE is inhibited. In conclusion, our results indicate that canine rangeliosis alters the activity of cholinesterase's, which may be involved in the pathogenesis of the disease, as well as various pathological conditions.

Biblioteca responsável: BR68.1