Background and aims: With the rapid developments in nanotechnology, ZnO-NPs are increasingly being used in various aspects of our lives and their toxicity on body is escalating. This study aimed to investigate the histo-pathological effect of orally and intraperitoneal administrations of toxic ZnO nanoparticles (ZnO-NPs) on kidney function in laboratory male mice Mus musculus.

Methods: In this experimental study, a group of 75 BALB/c male mice of about 6 weeks were randomly divided into three groups (n=25). Each of mice in both orally- and intraperitoneal treated groups received the same concentration of ZnO-NPs (0.05 g/ml). On days 1, 7 and 14 of the experiment blood was taken directly from the heart to get serum. The data were analyzed by one-way ANOVA using SPSS. A significant difference was considered to be P<0.05. Finally, samples of kidney tissue were prepared and analyzed.

Results: In both intraperitoneal and oral treatment groups of mice, a significant increase in the serum level of BUN and Cr at day 7 was found with symptoms of vascular distension and infiltration of blood cells into the vessels, interstitial renal tubules and vacuolation of parietal cells of proximal tubules (necrosis). The observed tissue damage intensity in the orally administered group was less as compared with the intraperitoneal one.

Conclusions: A toxic concentration of ZnO-NPs causes serious physiological and pathological damages including congestion, necrosis in some cells, hydration of proximal tubules and kidney swelling in the oral group. However, the observed damages in the intraperitoneal group were lower as compared with the oral one.