Study on the effect of nanosized titanium dioxide for reproductive system of male mice

Objective While research on the potential toxic properties of nanomaterials is now increasing, the in vivo effects of zinc oxide (ZnO) on the main organs were emergent to know. In this study, the effects of nanometer ZnO on male mice, particularly the reproductive system were evaluated. Methods Forty-five male ICR mice, aged 6-7weeks, were randomly divided into control group and two experimental groups which were intraperitoneally injected with 200 (n=15)and 500 mg/kg ZnO(n=15) every other day for 5 times. Control group (n=15)was injected equal volume saline. After one week of treatment, the coefficients of organs and serum biochemical parameters, gonadal hormone (T and E2) were measured, respectively. Main organs were observed in pathology. Sperm count, sperm motility rate, abnormal sperm rate were observed under microscope. The distribution of nano-particles in liver and testis were observed by Electron microscopy. Germ cell apoptosis was evaluated by TUNEL. Results Compared with the control group, the organ coefficient were not significantly changed after lower-dose(200mg/kg) nano-ZnO administration, but the higher dose (500mg/kg) nano-ZnO administrated mice show significantly elevated quality coefficient of spleen and kidney (P0.05). In low-dose group, serum ALT、TBIL、CHO、UA、CK were significantly changed (P0.05). In contrast, the high-dose treated mice showed significant changed levels of serum ALT、AST、TBA、AKP、TG、CHO (P0.05) indicating the liver damage. Moreover, serum BUN、Cr and UA increased obviously, suggesting the kidney damage. In both of these two administrations, the levels of serum testosterone (T)and estradiol (E2) were equivalent with the control (P0.05). The observation of reproductive function found that the decreased sperm count and function in both of two treatments. Meanwhile, the results of TURNEL assay showed that the apoptosis of testicular germ cell increased especially in high-dose group with the significant change of apoptosis index (P0.05). Edema and degeneration in hepatocytes of the mice exposed to high-dose zinc oxide were found. Renal pathological changes and inflammatory cells infiltration in pancreas interstice were obvious. Besides the above organic tissues, no other significant histopathological changes were found in the heart, testis and epididymis. Nano-ZnO were gathered in lysosomes and mitochondria of the liver cells and testicular cells, which can be found by Electron microscopy. Conclusion The low dose of nano-ZnO may have mild effects on the mouse liver, kidney and heart function, moreover, the live sperm rate and the rate of sperm deformity were affected in this group. For high dose of nano-ZnO treated mice, the damage on the liver, kidney and heart were obvious. Especially, the reproductive system was damaged with the decreased sperm count and function as well as testicular germ cell apoptosis.