Mitochondrial biochemical and histopathological defects induced by the herbicide pendimethalin in tilapia fish (Oreochromis niloticus).

The mitochondrial defects were evaluated after administering tilapia fish, Oreochromis niloticus to sublethal doses (1.02 and 5.10 mg kg-1) of the herbicide pendimethalin (PD). All treatments exhibited a decrease in the cytochrome contents of gills, liver, and brain samples after 12, 24, and 48 h compared with the untreated individuals. However, malondialdehyde (MDA) levels were significantly increased in gills and liver samples. Also, the histopathological profiles showed significant swelling in mitochondria and intracellular spaces in cytoplasm of gills samples. The mitochondrial defects in the treated fish showed a slight decline in cytoplasm/mitochondria ratio (0.92-fold) compared to the control. In hepato-sections of treated fish, destructed mitochondria with less dense matrix as well as some vacuolated mitochondria with matrix disoriented cristae were noted. Similar patterns were observed in brain sections, where destructed axons and a significant decline in cytoplasm/mitochondria ratio (0.52-fold) were found. Therefore, the use of mitochondrial defects and histopathological alterations might represent good markers to assess the impact of herbicides on aquatic organisms. Moreover, the disorganization of cell components is considered an important sign of organ dysfunction.