Histological Biomarkers and Protein Expression in Hyphessobrycon eques Fish Exposed to Atrazine

Pesticides are one of the main sources of pollution on the planet, affecting different environments. The aim of the study was to evaluate the chronic effect of atrazine (ATZ) on brain, gill, and liver histology and the clinical signs of intoxication in Hyphessobrycon eques fish and to determine the effect on the expression of proteins related to proliferation, damage, death, and cellular stress pathways. The chronic toxicity test was performed during 30 days of exposure to ATZ. Concentrations of 0.57, 1.14, 5.74, and 11.50 mg L −1 were applied and there was a control. Aquariums with a capacity of 5 L of water were used with aeration pumps containing 5 animals per replica, weighing between 1.0 ± 0.2 g per organism. At the end of the chronic toxicity tests of ATZ for H. eques , samples of the gills, brain, and liver were collected for histological analysis. The same organs were collected and stored in cryogen tubes in liquid nitrogen until the moment of extraction and then massaged mechanically for the Western-blot technique. In the histopathological analyses, the gills showed the greatest changes in relation to the other organs, such as the loss of support of the secondary lamellae, and the fish also showed a loss of swim bladder capacity. In conclusion, ATZ in the environment, in long-term exposure, can cause histological and biochemical effects, affecting the survival and proliferation of cell pathways. Graphical abstract