Purinergic signalling as a potential pathway for trichlorfon induced-inflammation and impairment of the immune response using freshwater silver catfish

Adenosine triphosphate (ATP) and adenosine (Ado) are the main molecules of the purinergic signalling involved in toxicological mechanisms induced by pesticides. These molecules participate in the regulation of immune and inflammatory responses due to their interaction with purinereceptors in the extracellular medium. In the literature, the ATP and Ado are related with pro-inflammatory and immunomodulatory effects, respectively. Thus, the aim of this study was to evaluate whether the purinergic signalling can be considered a potential target for trichlorfon-induced inflammation and impairment of the immune response. Seric and splenic triphosphate diphosphohydrolase (NTPDase) activities using ATP as substrate were reduced at 22 mg/L after 48 h of exposure compared to the control group, while NTPDase activity using ADP as substrate was lower only in the serum of silver catfish at the same period. On the other hand, seric and splenic adenosine deaminase (ADA) activities and metabolites of nitric oxide (NOx) levels were increased at 22 mg/L after 48 h of exposure compared to the control group. The enzymatic activity of the purinergic signalling did not return to control levels after 48 h of recovery period in trichlorfon-free water. Based on these evidences, we concluded that trichlorfon interferes with the purinergic signalling, causing impairment of the immune and inflammatory responses by reducing ATP hydrolyses, possible leading to its accumulation in the extracellular environment. In addition, there is an increase in Ado desamination and possible reduction of it in the extracellular medium, leading to a self-sustained pro-inflammatory deleterious cycle. In summary, the purinergic signalling can be considered a potential target for trichlorfon-induced inflammation and impairment of the immune response in freshwater silver catfish at exposure to 22 mg/L.