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

Abstract

The effects of swim bladder injection with thioglycolate, Escherichia coli lipopolysaccharide (LPS) and heat-inactivated 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.