In view of the important biological role of histamine on vascular permeability and a few data of this autacoid in teleost fish, this study proposes to evaluate the role of histamine in the acute inflammatory response in Nile Tilapia challenged with an inoculum of Aeromonas hydrophila, submitted or not to treatment parenteral with antihistamine H1 promethazine receptors by: analysis in this cell exudates; evaluation of leukocyte, erythrocyte and thrombocytes; study of vascular permeability. In carrying out this research, 120 Nile Tilapia (Oreochromis niloticus), with average weight of 100g, stemming from the same spawning will be randomly assigned to 10 tanks with a capacity of 250L of water each, constituting three treatments: T1 = no antihistaminic (control); T2 = with administration of promethazine intramuscularly; T3 = with administration of promethazine in the coelomic cavity. In the first experimental trial seven animals per treatment will be sampled for the study of cell accumulation in aerocistitis and hematological analysis into three periods: 6, 12 and 24 hours post- bacterial challenge (HPD). In a second experiment five animals per treatment will be sampled for analysis of vascular permeability performed 2, 4 and 6 HPD, for evaluating the time response, constituting 9 experimental groups: three per treatment. A 10° group will consist of fish not subjected to any manipulation to provide reference values for the study (Standard Physiological, n = 7). The administration of the antihistamine promethazine (Phenergan ®) will be held at the time of bacterial challenge, intramuscularly in the left dorsolateral region at a dose of 0.5 mg/kg IM oily solution diluted 1:1 (T2) and the coelomic cavity but the same dose in aqueous solution (T3). At necropsy 6, 12 and 24 HPD, will be collected: this swim bladder to quantify inflammatory exudate and evaluation of inflammatory cells; Blood samples of fish by puncturing the vessel flow for hematologic evaluation and study of vascular permeability exudate is harvested 2, 4 and 6 HPD. Thus, the correlation between the cellular inflammatory exudate in this study, cell count and evaluation in vascular permeability will provide important information in understanding the involvement of histamine in the pathophysiology of acute inflammatory reaction in Tilapia.
News published in Agência FAPESP Newsletter about the scholarship: