Immunohistochemical examination of HSP70, PCNA, 8-OHdG, iNOS and apoptosis in the gills of Lake Van fish ( <i>Alburnus tarichi</i> (Güldenstädt, 1814)) after esfenvalerate exposure

Lake Van fish is an endemic carp species adapted to the soda waters of Lake Van. As a result of agricultural and livestock activities around the lake, many environmental pollutants are dumped into the lake as waste. Esfenvalerate is a pyrethroid pesticide used extensively in agricultural areas in the region. In this study, Lake Van fish were exposed to a sublethal dose of esfenvalerate (0.158 µg/L) for 24, 48, 72, and 96 hours, and their gill tissues were examined immunohistochemically. Histopathological analysis determined that hyperplasia and necrosis occurred in the gill tissue as a result of exposure. Additionally, the heat shock protein 70 (HSP70), proliferating cell nuclear antigen (PCNA), 8-hydroxy-2’ -deoxyguanosine (8-OHdG), and nitric oxide synthase (iNOS) positive cells and the number of apoptotic cells were determined by immunohistochemistry in gills of Lake Van fish exposed to esfenvalerate. The density of cells containing HSP70 and PCNA increased at 24 and 48 hours of exposure to esfenvalerate. 8-OHdG occurred in gill tissue as a result of esfenvalerate exposure, and the number of damaged cells increased over time. The number of apoptotic cells and containing the inducible isoform of iNOS increased in the gill tissue as a result of esfevalerate exposure. Overall, it was determined that esfenvalerate had a toxic effect on Lake Van fish gills.