The influence of lead nanoparticles on the morpho-functional changes of rat liver during the postexposure period.

Lead as any heavy metals may be found in soil, water, air, and is used in everyday life. Once in the body, it causes toxic effect, making the liver, which is one of the main organs of detoxification, suffer. Recently, the study of the action of not only ionic forms of lead, but also its nanoparticles, has become topical. The study aims at determining changes in the liver of rats and biochemical changes in their blood both at late term of exposure to nanoparticles of lead compounds and in the post-exposure period. The study was performed on 120 male rats of Wistar line, which were divided into two series, each series containing four groups. The first and the second groups of animals were intraperitoneally injected with colloidal solution of nanoparticles of lead sulfide of 10 and 30 nm in size, and the third group were intraperitoneally injected with a solution of lead nitrate. The fourth group of animals served as control. In the first series, the investigated substances were administered 60 times within 12 weeks. In the second series, after 60-fold administration of the investigated substances, the exposure was discontibued and animals were observed for 6 weeks-overall duration of 18 weeks. Histological, morphometrical and biochemical methods were used. The body weight was reduced in the rats exposed to PbSnano1 at week 12 of experiment and in rats exposed to both PbSnano1 and Pb(NO3 )2 in the second series. Absolute liver weight increased at week 12 of experiment in all experimental groups. In the second series this value almost reached that of the control level. Relative liver weight in the animals of all experimental groups was higher than that in the control at week 12 of experiment. In the second series this value remained higher in rats exposed to PbSnano1 . After 12 weeks of exposure dystrophic changes in the liver were found in all experimental groups. At week 6 after the exposure (the second series) destructive changes in the liver decreased. Total protein, albumin, glucose, total lipids, cholesterol, triglycerides content in blood serum corresponded with morphological data. The experiment has demonstrated that the 12 weeks long exposure to lead nanoparticles had harmful effect on the liver. Within the postexposure 6-weeks period structural changes in the liver and biochemical changes in blood serum decreased. Biochemical changes in blood serum corresponded to the morphological data. By many parameters PbSnano1 had more pronounced harmful effect. Toxicity of PbSnano2 and Pb(NO3 )2 were comparable.