Aluminium oxide nanoparticles induced irrevocable damages in gill, liver and brain tissues of the freshwater Fish, Oreochromis mossambicus (Peters, 1852)
PV Vidya, KC Chitra
Aluminium oxide nanoparticles (Al2O3NPs) or nano-sized alumina is the engineered nanoparticles having wide range of application in engineering, science and technology. Histopathological alterations induced by Al2O3NPs were studied in the gill, liver and brain tissues of the freshwater fish, Oreochromis mossambicus. Al2O3NPs at 4 mg/ L (1/10th of LC50-96 h) was exposed for short-term (96 h) and long-term (60 days) durations maintaining the control group. Treatment withdrawal for 60 days was also conducted in toxicant-free water to assess if the toxicity of nanoparticles revokes to normal. Histopathological changes in gill after 96 h showed epithelial upliftment, hypertrophy and hyperplasia of gill arches, aneurysm, lamellar curling and absence of secondary lamella. The degree of damages was more severe after 60 days of nano-alumina exposure showing severe mucous deposition, vacuolization, hyperplasia, aneurysm, and absence of secondary lamellae. Morphology of liver tissue showed pathological changes as segmentation and degeneration of hepatic cytoplasm with spindle shaped nucleus after 96 h of exposure. When the treatment period is increased to 60 days showed vacuolization and severe necrosis. Exposure to nanoparticles for 96 h showed lesions in brain tissue as indicated by mild vacuolization in neural cells, however, after 60 days more degenerative changes as intracellular edema was observed. Duration of exposure have profound effect on structural damage of gill, liver and brain tissues. Treatment of nanoparticles when withdrawn for 60 days also showed similar pathological alterations as the treatment groups thereby indicating Al2O3NPs induced irrevocable damages in gill, liver and brain tissues of the freshwater fish, Oreochromis mossambicus. The present observations clearly demonstrated that nanoparticles exhibited significant and permanent morphological changes in vital tissues, which could be one of the reasons behind the decline of fish population in toxicant-exposed aquatic environment.