| [Objective] Over the years, the study of fluoride showed that moderate fluoride is benefit to maintain normal metabolism of calcium and phosphorus, it also can prevent dental caries. But excessive fluoride may lead to damage to various tissues and organs what causing fluorisis. The effects of fluoride on male reproductive system are manifold, while the amount of research on reproductive endocrine is less. By using real-time PCR, histological section and transmission electron microscopy, combined with the changes of reproductive hormone levels in serum, bone fluoride content and sperm malformation rate, this paper we give a comprehensive analysis of the effects of fluoride exposure on hypothalamus-pituitary-testicular axis of mice, and explore its molecular mechanism of the reproductive system damage furthermore.[Method] 48 healthy young adult male Kunming mice were randomly divided into four groups and named control group, low fluoride group, medium fluoride group and high fluoride group. The control group mice were administrated with ultrapure water (Milli-Q Water purification system), low F group treated with 25 mg/L NaF, medium F group treated with 50 mg/L NaF, and high F group treated with 100 mg/L NaF. Animals were kept for 60 days. During the process of feeding, we should keep recording the condition of growth and weight regularly. After exposure, collecting serum, sperm, hypothalamus, pituitary, testis and femur used for determining the relevant indices including using a fluoride Ion selective electrode to measure the bone fluoride content, using radioimmunoassay to measure reproductive hormone levels in serum, using HE staining and transmission electron microscopy to observe the changes of tissue structure, using real-time PCR to detect the mRNA expressions of reproductive related genes, etc.[Results] ①Compared with the control group, The bone fluoride content significantly increased in fluoride treated groups, and it significantly difference especially in medium fluoride group and high fluoride group (P<0.001); however, there were no significant differences in the body weight, body weight gain and the main organ coefficients. ②The malformation ratio of sperm significantly increased in the high F group compared with the control group (P<0.05), while there were no significant differences in serum sex hormone levels of FSH, LH and testosterone compared with the control group (P>0.05). ③or histological structures of the hypothalamus and pituitary, there were no noticeable changes compared with the control group. However, in testis of fluoride treated groups, we can abserved lesions in different degree, especially in high fluoride group. In lumen, we can see the mature sperm were significantly decreased and disorganized spermatogenic cells and spermatozoa were significantly increased, the number of layers were reduced, the distance between seminiferous tubule was increased. What’s more, Leydig cell vacuolization can also be observed.④The results of transmission electron microscopy showed that in hypothalamus of high fluoride group, euchromatin distributed scattered and heterochromatin gathered into a mass and margination. The swollen nuclear membrane can also be seen. In myelin, the configuration presented discrete like the onion skin, and the arrangement was ambiguity and disordered. In pituitary of high fluoride group, irregular nucleus, concentrated chromatin, swollen mitochondria, vacuole bodies and dilated endoplasmic reticulum can be seen. In testis of high fluoride group, we observed swollen mitochondria with aberrant cristae, cytoplasmic vacuolar changes and heterochromatin agglutination in spermatogonium, spermatogonium and sertoli cell. Also, the acrosome of the sperm cell membrane rupture. In leydig, we can see nuclear division and mitochondria vacuolization. ⑤The results of real-time PCR showed that, compared with the control group, there were no statistically significant differences in the expressions of GnRH mRNA in hypothalamus and FSHβ, LHβ and GnRH-R mRNA in pituitary (P>0.05). However, the expressions of FSHR, LHR, INHα, INHβB and SHBG mRNA were markedly decreased in testis.[Conclusion] Taken together, our present study showed that the adverse effect of F on reproductive function was mainly elucidated through damaging testicular structure and function, and the effect on hypothalamus and pituitary through crossing the blood-brain barrier was secondary along HPTA after 60 days exposure. |
PDF Full Text Request