Mechanismof reproductive toxicity of sub-chronic exposure to nickel oxide nanoparticles in male SD rats / 中国职业医学

ABSTRACT

@#Objective To investigate the effects of sub-chronic exposure of nickel oxide nanoparticles （Nano NiO） on endocrine function of male SD rats，and to analyze the toxicity and mechanism of Nano NiO on testicular cells. Methods The specific pathogens free male SD rats were randomly divided into five groups with ten rats in each group. Rats in low-，medium and high-dose groups were given Nano NiO suspension with the mass concentration of 0.16，0.80 and 4.00 g/L，respectively； rats in blank control group were given equal volume of 0.9% sodium chloride solution；rats in positive control group were given micron nickel oxide suspension with the mass concentration of 4.00 g/L. Drip every three days for nine weeks. After the Nano NiO exposure，atomic fluorescence spectrometry was used to determine the levels of nickel in the blood and testicular tissue. The enzyme-linked immunosorbent assay was used to detect serum level of sex hormone. The ploidy ratio，cell cycle and apoptosis rate of testicular cells were analyzed by flow cytometry. Western blotting was used to detect the relative expression of apoptosis related proteins in the testis. Results The level of nickel in blood and testicular tissue of rats in positive control group and the three doses groups were higher than that of blank control group（all P<0.05）. The level of nickel in blood and testicular tissue of rats in the medium-dose and high-dose groups were higher than that in the positive control group（all P<0.05）. There was a positive correlation between the level of nickel in blood and testicular tissue（P<0.01）. The serum levels of testosterone，follicle stimulating hormone（FSH）and luteinizing hormone（LH）in the medium- and high- dose groups were lower than that in blank control group（all P<0.05）. However，there was no significant difference in serum gonadotropin-releasing hormone among all groups（P>0.05）. Compared with the blank control group，the proportion of haploid and diploid cells and the ratio of cells in G0/ G1 and S phase decreased in the medium- and high-dose groups（all P<0.05），the tetraploid cell ratio，G2/M cell ratio and early apoptotic rate of testicular cells increased（all P<0.05）. Compared with the blank control group，the relative expression of B-cell lymphoma-2（BCL-2）protein and the ratio of BCL-2/BCL-2-related X protein（BAX）in testicular cells of rats decreased in the medium- and high-dose groups（all P<0.05），the relative expression of BAX and caspase-3 protein were increased（all P< 0.05）. Compared with the positive control group，the level of nickel in blood and testicular tissue of rats was increased in the high-dose group（all P<0.05），the ratio of haploid cells and the ratio of testicular cells at G0/G1，S phase and BCL-2 /BAX ratio in testicular tissue decreased（all P<0.05），the tetraploid ratio，G2/M phase ratio，early apoptotic rate and total apoptotic rate of testicular cells increased（all P<0.05）. Conclusion Exposure to Nano NiO could inhibit the secretion of FSH，LH and testosterone in male rats. Nano NiO can cross the blood-testosterone barrier，interfere with the proliferation of testicular cells， induce apoptosis of testicular cells through the mitochondrial apoptosis pathway，inhibit the formation of haploid sperm cells， resulting in disorders of spermatogenesis.