Cellular alterations and damage to the renal tissue of marine catfish Arius arius following Cd exposure and the possible sequestrant role of Metallothionein

Highlights: • Cd induced structural and functional impairment of the kidneys of Arius arius. • Histomorphometry, DNA damage and apoptosis proved kidney damage. • MT synthesis was confirmed by Western blotting. • Cd-induced MT synthesis was time-dependent and positively correlated. • Cd accumulation and MT induction may be biomarkers for Cd toxicity studies. Cd is a non-degradable heavy metal pollutant with no known biological role. When taken up by living organisms from the environment, it causes extensive tissue damage. Here, we studied the effects of exposure to 20 mg/L⁻¹CdCl₂for 0, 24, 48, and 72 h on the renal tissue of marine catfish Arius arius. Cd uptake, metallothionein (MT) induction, microarchitectural alterations, DNA fragmentation, and caspase-3 activity were studied. Cd and MT levels were time-dependent and positively correlated. The diameter of the Bowman's capsule and tubules was significantly increased. Meanwhile, the density, diameter, and volume of the glomerulus as well as the density and volume of tubules decreased. Cd induced apoptosis though elevatedcaspase-3 activity. These results support the notion that exposure to sublethal Cd levels induces oxidative stress, leading to structural and functional impairment of the kidneys. Cd uptake and MT induction can serve as useful environmental biomarkers.