Acute aerocistitis induced by thioglycolate, lipopolysaccharide and inactivated Aeromonas hydrophila in Piaractus mesopotamicus: hematological effects

The effects of swim bladder injection with thioglycolate, Escherichia coli lipopolysaccharide (LPS) and heat-inactivat ed Aeromonas hydrophila were assessed on hematological responses in pacu, Piaractus mesopotamicus (Characidae). A quantitative assessment was done on erythrocytes, thrombocytes e leucocytes at 6, 24, and 48 h pos-injection of the inflammatory agents and compared with fish injected with saline solution (control). Fish injected with inactivated A. hydrophila showed a reduction of erythrocytes and hemoglobin, whereas the hematocrit increased 6 h pos-injection. The results show that thioglycolate and LPS also induced a reduction on hemoglobin and an increase on the hematocrit. The thrombocytes count decreased 6 h post A. hydrophila injection, whereas increased 48 hours post LPS injection. The leukocytes count increased after 6 h post A. hydrophila injection, while the lymphocytes and PAS-positive granularleukocytes (PAS-LG) count decreased after 24 h post injection. In fish injected with thioglycolate or with LPS showed an increase in the LG-PAS counts when compared to A. hydrophila or control groups. The monocytes count was not affected by the different inflammatory agents.(AU) Os efeitos da injecao de tioglicolato, lipolissacaridio de Escherichia coli e Aeromonas hydrophila inativada na bexiga natatoria de pacus, Piaractus mesopotamicus (Characidae) foram avaliados quanto as respostas de celulas vermelhas, leucocitos e trombocitos do sangue. Ensaios quantitativos de eritrocitos, leucocitos e trombocitos foram realizados 6, 24 e 48 h apos os estimulos e comparados com peixes que receberam solucao salina 0,65% pela mesma via. Peixes inoculados com A. hydrophila apresentaram reducao do numero de eritrocitos e da taxa de hemoglobina enquanto o hematocrito aumentou 6 h apos o estimulo. Os resultados mostraram que o tioglicolato e o LPS tambem induziram reducao da hemoglobina e aumento do hematocrito. A contagem de trombocitos diminuiu 6 h apos a inoculacao de A. hydrophila inativada e aumentou 48 horas apos a injecao de LPS. A contagem de leucocitos aumentou 6 h apos a inoculacao de A. hydrophila enquanto a de linfocitos a leucocitos granulares PAS positivos (PAS_LG) diminuiu 24 h depois. Peixes injetados com tioglicolato o LPS apresentaram aumento do numero de LG_PAS em relacao aos inoculados com A. hydrophila inativada ou grupo controle. A contagem de monocitos nao foi afetada pelos diferentes agentes.(AU)