A Histological Study on the Acute Effect of Zinc Oxide Nanoparticles Administered by Different Routes on Albino Rat Lung

Zinc oxide nanoparticles (ZnO NPs) are considered the most frequently utilized NPs, so the potential for human exposure has increased tremendously. Hence, the study is aimed to compare the histopathological effects of high and low doses of ZnO NPs administered intranasally or intravenously on lung tissue of adult rat's male albino.

Thirty-five male Wistar rats were divided into Group I; control group, Group II (intranasal administered group) was subdivided into Subgroup IIA and IIB, in which the animals were injected with 4 and 30 mg/kg of ZnO NPs, respectively. Group III (intravenous administered group) was subdivided into two subgroups with the same doses as Group II. Blood samples were collected after 24 h for estimating serum level of lactate dehydrogenase. Rat lungs were processed for histological, immunohistochemical, and ultrastructural analysis.

ZnO NPs caused thickening of interalveolar septa. Extravasated red blood cells were noticed in the alveolar lumen and in some bronchioles. Many dilated blood vessels exhibited focal disruption and focal thickening of their wall. Collagenous fibers were deposited in the interalveolar septa and the walls of bronchi. Tumor necrosis factor-alpha immune reactivity was significantly increased. These findings increased on dose increase, mainly in the intranasal administered group when compared with the intravenous group.

ZnO NPs administration caused toxic effects on the histological structure of albino rat lung. These effects were route and dose-dependent, being more obvious after intranasal administration.