Subacute toxic effects of silver nanoparticles oral administration and withdrawal on the structure and function of adult Albino Rats' hepatic tissue

Abstract

Products containing Silver nanoparticles (Ag NPs) are becoming vastly used in our daily life. The widespread increased introduction of Ag NPs in many aspects of life has raised researchers' concerns regarding their safety and toxicity for biological and environmental life in the past few years. The current study aimed to explore the subsequent effects of Ag NPs withdrawal, following short-term oral administration. Eighteen rats were assigned randomly into three groups (control group "1" and AG NPs treated groups "2" and "3"; 6 animals each). The control group received normal food and tap water while groups 2 & 3 received 0.5 ml of a solution containing 25 ppm Ag NPs for 14 days. Group 2 rats were sacrificed on day 14 whereas group 3 was left for another 14 days of particle cessation followed by euthanasia on day 28. Functional assessment was done by liver enzyme assays, hydrogen peroxide activity, hepatic Bdnf expression, and P53 immunoreactivity. Hepatic tissue structural assessment was done via hematoxylin and eosin, periodic acid-Schiff as well as Masson's trichrome stains. The results revealed a significant elevation of Hydrogen peroxide in group 2 only compared to the control group. Hepatic Bdnf and liver enzymes were both insignificantly affected. Structural abnormalities and enhanced apoptosis in hepatic tissue were found 14 days after ceasing the nanoparticles. In conclusion: Structural and functional insults following Ag NPs oral administration continues after particle withdrawal, and interestingly they do not necessitate apparent reflection on liver enzyme assays.

Keywords: ALT, Alanine Transaminase; AST, Aspartate Transaminase; Ag NPs, Silver Nanoparticles; Bdnf, Brain-derived neurotrophic factor; H&E, Hematoxylin & Eosin stain; H2o2, Hydrogen Peroxide; HCC, Hepatocellular Carcinoma; Hepatic Bdnf; Hepatotoxicity; Hydrogen peroxide; Liver enzymes; Masson's trichrome stains; NaBH4, Sodium Borohydride; Nanoparticles, (NPs); PAS, Periodic acid-Schiff; PVP, Polyvinyl Pyrrolidone; RNA, Ribonucleic acid; ROS, Reactive Oxygen Species; SGOT, Serum Glutamate oxaloacetate Transaminase; SGPT, Serum Glutamate pyruvate Transaminase; Silver Nanoparticles (Ag NPs); TEM, Transmission Electron Microscopy; TRI, Masson's trichrome stains; Transmission Electron Microscopy; UV–Vis, Ultraviolet–Visible Spectroscopy; Ultraviolet–Visible Spectroscopy; ppm, Parts Per Million.

Graphical abstract

Fig. 1

a TEM characterization, showing spherical Ag NPs. Fig. 1b: UV Vis reveals no stable aggregates and homogeneity in the size distribution of Ag NPs.

Fig. 2

Photomicrograph sections in the hepatic tissue of rats using H& E stain.Fig. 2a: A liver tissue section from a control rat showing normal central veins and hepatocyte (H) which are arranged into hepatic cords radiating from the central vein (CV). Fig. 2b: Liver tissue from a rat treated with nanosilver (group 2) showing congested & dilatated central vein (CV) and vacuolated ballooned hepatocytes (H) with karyolytic (K) and pyknotic (P) nuclei. Fig. 2c: Hepatic tissue from a rat in group 3 showing congested & dilatated central vein (CV) and vacuolated ballooned hepatocytes (H) with karyolytic (K) and pyknotic (P) nuclei. [H&E X400].

Fig. 3

Photomicrograph sections in the hepatic tissue of rats using PAS stain.Fig. 3a: liver tissue section from a control rat showing positive PAS reaction in the cell cytoplasm. Normal accumulations of reddish stained glycogen particles at one pole of the hepatocyte are shown. Fig. 3b: liver from rat administered nanosilver (group 2) revealing decreased PAS reaction in the cytoplasm of hepatocyte more than the control group. Fig. 3c: hepatic tissue section from a rat in group 3 displaying decreased PAS reaction in the cytoplasm of hepatocyte more than group 2. [PAS X400].

Fig. 4

Photomicrograph sections in the hepatic tissue of rats using MTS stainFig. 4a: liver tissue section from a control rat with minimal greenish collagens around the central vein. Fig. 4b: a section from hepatic tissue from a rat given nanosilver (group 2) with no change in the greenish collagenous fibers surrounding the central vein. Fig. 4c: a section of liver from rat from group 3 displaying no change in the greenish collagenous fibers encircling the central vein [Masson's trichrome stain X 400].

Fig. 5

Photomicrograph sections in the hepatic tissue of rats using P53 stain 5a: liver tissue section from a control rat displaying mild brownish reaction. Fig. 5b: liver tissue section from a rat given with nanosilver (group 2) revealing moderate immunoreactivity of P53 in the form of brownish color. Fig. 5c: a section of hepatic tissue from a rat from group 3 with intense immunoreactivity of P53 in the form of brownish color [P53 immunostainning × 400].