| Background:Nano particles are a kind of materials with structures ranging from 1-100 nm in at least one dimension. They have higher surface area to volume ratio, smaller size, higher catalytic efficiency, more surface active sites and higher adsorption capability. Nano-scale materials can have different special physical and chemical properties compared to conventional materials, which makes nano-materials and nano-technology become a hot spot in recent decades. Studies have demonstrated that nanoparticles can be swallowed by macrophages, which release superoxide free radicals and cause oxidative damage, start apoptosis, induce inflammatory response and so on, finally affect growth and metabolism of organisms. Some in vivo studies have confirmed that certain nano particles cause damages to cells and organs, such as liver, kidney, lung and brain. For example, carbon nanotubes may be toxic to the respiratory and digestive systems, quantum dots can cause severe damage to liver and kidney, a long term exposure of silver nanoparticles with high dose is also dangerous to kidneys, liver and lung. Yet little researches are focused on the effects of these nanomaterials on endocrine metabolism. This article aims to find out the effects of four kinds of nanoparticles (single-walled carbon nanotubes, multiwalled carbon nanotubes, quantum dots and silver nanoparticles) long exposure on bone metabolism in mice, so as to provide data support for the evaluation of the safety of nanomaterials.Objective:To observe the effects of four kinds of common nanoparticles (single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs), quantum dots (QDs) and silver nanoparticles ( nAg))on bone metabolism in mice.Methods:8-week-old Kunming mice were treated for 6 weeks with the nanoparticles at 3 doses or vehicle by peritoneal injection three times per week. The whole body X-ray, biomechanical parameters and serum Ca levels were measured to evaluate bone metabolism of the mice. Total protein content in the lavage of the peritoneal cavity, inflammatory factors content in the serum as well as mRNA content of Inflammatory factors in the J774A.1 cell were to be measured.Results:Compared to their vehicle controls, osteolysis incidence of tibia was significantly increased in MWNTs(P<0.05), and there is clear difference between MWNTs and vehicle control in the bone ash ratio and the bone biomechanical properties(P<0.05), besides, serum Ca level was increased in high dose(P<0.05). 2. Osteolysis incidence was increased in SWNTs, and bone ash ratio and the bone biomechanical properties were significantly decreased in high dose and middle dose(P<0.05), while there was no significantly difference in serum Ca levels(P>0.05). 3. There was not clear difference in osteolysis incidence and serum Ca levels between QDs and vehicle control(P>0.05), however, statistical significance was found in bone ash ratio, maximum load and elastic load of high dose and middle dose(P < 0.05). 4. Nonsignificant result was found in different doses of nAg(P>0.05). 5. The levels of total protein content in the lavage of the peritoneal cavity, surem IL-1βand IL-6 as well as IL-1βand IL-6 mRNA content in the J774.1 cell were dramtically increased(P<0.05), while there was no significantly difference in levels of TNF-αin both serum and in vitro(P>0.05). 6. There was no significantly change in protein content in the lavage of the peritoneal cavity and levels of inflammatory factors of surem and the 774.1 cell. Conclusion:Chronic exposure to multiwalled carbon nanotubes can promote osteolysis, reduce bone mineral density and change the bone biomechanical properties; single-walled carbon nanotubes and quantum dots probably influence the bone metabolism; silver nanoparticles don't influence the bone metabolism. 2. Both single-walled carbon nanotubes and multiwalled carbon nanotubes affect on bone metabolism by releasing IL-1βand IL-6 from neutrophilic granulocytes, which increase the procedure of differentiation of osteoclasts. |
PDF Full Text Request