Liver morphometry and histopathology effects in Astyanax lacustris exposed to lambda-cyhalothrin pyrethroid insecticide

Abstract

Lambda-cyhalothrin (LC) is a pyrethroid insecticide employed to manage various arthropods as an alternative to persistent insecticides with minimized toxic effects on birds and mammals. However, LC causes oxidative and neurotoxic damages in fish Danio rerio. Effects of LC in morphology of liver of fishes are scare. We aimed to establish the lethal concentration (LC₅₀ 96 h) of pyrethroid LC for Astianax lacustris. Then, we compare liver responses of sublethal doses of LC (i.e. 10.30 µg/L) for acute (i.e 1- and 3-days post-exposure - dpe) and chronic (i.e 6 and 12 dpe). We sought to identify pathological changes and compare liver histometric remodeling in fish subjected to acute and chronic toxicity tests. For this, liver histological changes were evaluated using the degree of tissue changes (DTC), followed by histomorphometric techniques determining structural volumetric density, glycogen cell density, and morphometry of hepatic tissue. We observed high hepatocellular injuries in exposed fishes. The main injuries included leukocyte infiltration, hyperemia, and pyknotic nuclei, especially 6 dpe. Hepatic glycogen storage decreases at 6 and 12 dpe showing metabolic damage. Both, density and volume of decreases after LC exposure in all exposure time. However, sinusoidal density increases after LC exposure, suggesting vascular hyperemia. These results show morphophysiological effects of LC at 10.30 µg/L in acute and chronic exposure represented by decreased glycogen storage, structural density, and volume of hepatocytes, in addition to a higher degree of histological changes.