This test aimed to evaluate the inflammatory response after inoculation of Aeromonas hydrophila and the Flavobacterium columnare, both inactivated by heat, and a group injected with 0.65% saline solution used as control in the swin bladder of Piaractus mesopotamicus. The animals were fed for 160 days with diets containing three concentrations of organic chromium (0, 12 and 36 mg / kg) and two concentrations of vitamin C (0 and 500 mg / kg) combined, thus setting up six different diets. Analysis of defense cells, and total percentage of each cell type were carried out after six, 24 and 48 hours after inoculation with the irritant. The results showed that the group supplemented with a diet containing only vitamin C received lower accumulation of inflammatory cells than the other groups. The greatest accumulation of total cells occurred after six hours of the application of irritant in the group supplemented with 500 mg of vitamin C combined with 36 mg of chromium, followed by diet containing 500 mg of vitamin C combined with 12 mg of chrome. The results also demonstrate that the bacterium Aeromonas hydrophila was the agent that caused increased irritability in three different times, gaining significance in the group inoculated with saline (p <0.05) since its peak in the initial six hours, and dropped in the hours following. The bacterium Flavobacterium colummare is behaved similarly on the amount of cells accumulated in relation to time, but did not cause irritation much greater than obtained in the control group. Regarding the number of cells present in the exudate of defense, the greatest number of thrombocytes was found in all fish supplemented with chromium and vitamin C, followed by lymphocytes and a lesser number of granulocutes. Therefore, we concluded that the bacteria A. hydrophila caused more irritation of pacus in the swin bladder, causing a greater accumulation of cells in total defense with sharp number of thrombocytes and the chrome has immunostimulating agent capacity in fish and that its association with vitamin C have synergistic effect, which can be demonstrated by greater accumulation of organic cells in defense of inflammatory exudate of fish fed diets supplemented with chromium and vitamin C.
Acknowledgment: This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo - Brazil (FAPESP - São Paulo Research Foundation), Grants 2018/24499-8 and CNPq 305007/2016-5.