The effects of cypermethrin-based insecticide (CBI), commonly used in aquaculture and agriculture, were evaluated in matrinxa (Brycon amazonicus) exposed to sub-lethal concentration (20% of LC50) for 96 h. Physiological and biochemical effects were studied through biomarkers: lipid peroxidation (LPO), glutathione (GSH), and ascorbic acid concentrations; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glucose-6-phosphate dehydrogenase (G6PDH) assays in the liver and gills. Besides, ions Na+, Cl-, and K+; protein and glucose concentrations were measured in the plasma. Red blood cells count (RBC), hemoglobin concentration (Hb), hematocrit (Ht), and hematimetric parameters were evaluated in the total blood. The NKA (Na+ /K+ ATPase) activity was assayed in the gills. The histopathological effects of CBI were also investigated in the gills. The liver and gill LPO increased 62 and 100%, respectively. The tripeptide GSH concentration reduced in the liver and increased in the gill of exposed fish. The SOD and CAT activities increased in the liver, whereas CAT reduced in the gill. Liver also presented an increase in G6PDH activity. Plasma Na+ and Cl- and glucose concentrations increased in the exposed fish. Levels of Ht, Hb and RBC were significantly increased. The gill NKA activity also increased. Exposed fish exhibited histological alterations in the gills such as hypertrophy and proliferation of chloride cells, blood vessels dilation, aneurysms and hemorrhage of the lamella. The histological index indicated moderate to heavy damage to the gills. CBI provokes liver and gills oxidative stress, gill structural damages, and ionic imbalance. A multi-biomarker approach allows us to see that B. amazonicus was unable to cope with CBI exposure.
Keywords: Aquatic pollution; Hematology; Histology; Osmoregulation; Oxidative stress; Pyrethroid.