| Fluorine(F) is a kind of nonmetallic elements which is essential to human body. Fluorine has strong electronegative character and widely exists in the form of fluoride in the nature. Appropriate amount of fluoride ingestion is beneficial to physiological activity. Such as decayed tooth prevention, calcium phosphorus supersession maintenance and nerve impulse conduction. Excessive fluorides produces strong toxicity to organism. It can do serious damage to many organs. In previous investigations, researchers attach more importance to study the harm of skeletal tissue done by fluoride. With the widely application of fluoride in industry and agriculture in recent yesrs, people pay more and more attention to the harm of nonskeletal system done by fluoride, Such as reproductive system. Fluorine impairs reproductive system mainly on three aspects. Firstly, it can destroy the structure of the chromosome in molecule level; Secondly, it can act on the testis directly and impairs configuration of the germ cells, the stertoli cells and the leydig cells; Thirdly, fluorine can damage secrete cells of hypophysis make the pituitany-gonad-axle change and affect the endocrine system. At present researchers lay particular emphasis on the later two aspects the impact of fluorine on male reproductive system.Telomerase is one of ribose nucleoprotein and is mainly consisted of RNA and protein. It can regard its endogenous RNA as template, synthesize DNA array and add it to the end of chromosome. The stability of telomoric in chromosome is important to normal gene expression. Telomerase's expression can also promote cell's hyperplasia. Expression of telomerase happens during the normal process of spermatogenesiswhich makes spermatogonium keep vigorous ability of hyperplasia and differentiation. Spermatogonium can split into spermatocyte. Spermatocyte can split into round spermatid which finally develops into sperm. All of these play an important role in maintaining the normal function of male reproductive system. No expression of telomerase in spermatogonium will lead to male's sterility. During the course of spermatogenesis, large amounts of telomerase's expression in seminiferous tubule will be important to the normal regulation of testicle normal reproductive ability of man. Does fluorine have effect on the expression of telomerase expression in the damage of male's reproductive system caused by fluorine? Few researches have been reported. Therefore, It's significant to study the impact of fluorine on spermatogenic cell's telomerase expression, which could offer us certain scientific basis to explore the reproductive toxicity produced by fluorine. Materials and methods1. Thirty healthy male SD rats weighted 50 to 65 gram were allocated into three groups randomly. There were ten rats in every group. The three experimental groups were control group, low-dose fluoride treatment group, high-dose fluoride treatment group. The NaF dosage for control, low-dose fluoride treatment, and high-dose fluoride treatment group were 0,10, and 20mg/kgBw/2d, respectively.2.According to the above-mentioned experimental dose, every fluoride treatment group was subcutaneously injected with NaF solution once two days to establish fluorosis rat model, while the control rats were injected with distilled water, At the end of the experiment, after putting the rat to death both testis and epididymide were dissected out and weighted for calculating their organic coefficient. The estradiol (E2) contents in serum were radioimmunochemically detected. The expression of telomerase was dected by ISH (in situ hybridization). The content of NaF in testis was measured by using fluorine selective electrode.The pathological alterations of testis were observed with light microscope for the order, shape, and structure of cells in spermatogenic epithelium. The sperm mounts, mobility, and aberration were observed.3. One-way analysis of variance (ANOVA)n x2"test and linear correlation analysis was used in the statistical test. There was significant difference when a was 0.05. Resultsl.As to body weight, testis weight, epididymide weight and their organic coefficient, significant differences were observed about the body, testis weight, epididymide weight and testis organic coefficient when high-dose fluoride treatment group compared to control rats (PO.05). Significant differences were observed about the body weight when low-dose fluoride treatment group compared to control rats (.P-O.05). Significant differences were observed about the body weight, testis weight and epididymide when high-fluoride treatment group compared to low-dose fluoride treatment group (P<0.05).2. The E2 contents in serum of different fluoride treatment groups were significantly lower than those of control groups, respectively (PO.05). The contents of E2 in serum of high- dose fluoride treatment group were lower than low- dose fluoride treatment group.3. Testis fluoride content of different fluoride treatment groups was significantly high than that of control groups, respectively (PO.05).Testis fluoride content of fluoride treatment groups was significantly increased with increased experimental fluoride dosage (PO.05).4. Compared to control rats, testicular pathological alterations in fluoride treatment groups showed that the normal figure and structure of seminiferous epithelium disappeared and was loosened, the number of mature sperm was reduced, and intraluminal deciduous sperm cells were observed. Meanwhile, the above-mentioned damages became more serious with the increased fluoride treatment dosage.5. The number of expression of telomerase in seminiferous tubule in different fluoride treatment groups was less than control group (PO.05). The expression of telomerase in seminiferous tubule was decreased with the increase of dosage, and the number of the expression of telomerase in each seminiferous tubule was decreasedwith the increase of dosage.6. The sperm count and mobility in different experimental group were lower than control group (P<0.05), sperm aberration was higher than control group (P<0.05). With the increase of dosage, sperm count and mobility were decreased (P<0.05), sperm aberration were increased (P<0.05).7. The content of E2 in serum of different fluoride treatment groups was positively correlated with the expression of telomerase in seminiferous tubule significantly, respectively (low-dose fluoride treatment groups, r=0.94, PO.01; high-dose fluoride treatment groups, r=0.92, P<0.01).8. The expression of telomerase in seminiferous tubule of different fluoride treatment groups were positively correlated with sperm count significantly, respectively (low- dose fluoride treatment group, r=0.99, PO.01; high-dose fluoride treatment group, r=0.88, P<0.0\).Conclusion1. Fluorine can cause the expression of telomerase in spermatogenic cell to drop.2. Fluorine can cause the concentration of E2 in secrum and the quantity of sperm to drop. It suggests that NaF damages the male reproductive system.3. E2-TERT-sperm way would possibly be one of the mechanisms about the reproductive system damage induced by fluorine. |
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