Biochemical and histopathological ultrastructural changes caused by ZnO nanoparticles in mice

Abstract

Five week-old mice were divided into a vehicle control group, and groups exposed to ZnO nanoparticles at low (0.5 g/kg), middle (1 g/kg), high (3 g/kg), and exceptionally high-dose (5 g/kg). After the first, second, third, and fourth weeks’ of exposure, blood biochemistry, histopathology, and electron microscopic ultrastructural changes in liver, kidney and spleen were investigated. Increased alkaline phosphatase activities were observed in all treated mice being statistically significant at higher dose. No changes were observed in the serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase, creatinine, blood urea nitrogen, and lipid levels. During the first and second weeks of the treatment, effects on the cytoarchitecture of liver, kidney, and spleen were not perceived while during the third and fouth weeks of treatment sporadic mild effects were seen. Ultrastructural electron microscopic changes in liver, kidney, and spleen were not observed for the low-dose group on the first, second, third, and fourth weeks, suggesting that exposure to ZnO nanoparticles at low dose is safe. Long-term (i.e., more than 28 days) exposure to the exceptionally high-dose resulted in sporadic changes in nuclear chromatin condensation, irregular nuclear membrane, polymorphic mitochondria, mitochondrial swelling, and vacuolation. ZnO nanoparticles could be well tolerated and no death occurred in any group of treated mice.

Keywords:

• ZnO nanoparticles
• ultrastructural changes
• nuclear chromatin condensation
• polymorphic mitochondria
• electron microscopy

Acknowledgments

The authors would like to acknowledge Sophisticated Advance Instrumentatiuon Facility, Electron Microscopic division, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India, for HR-TEM observation. Authors also would like to thank the Indian Council of Medical Research, New Delhi, India for their partial support and funding of this project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Indian Council of Medical Research, New Delhi, India, for their partial support and funding of this project.