The Study Of Fluoride On Endocrine Disturbing Effect Of People And Animals

Fluoride widely exists in the nature and in various areas of medicine, particularly in dentistry, as well as in agriculture and industry became very popular in the 20th century. It induces diseases either absent or excessive. Appropriate fluoride is beneficial to preventing caries, to maintaining nerve transmission, as well as to supporting calcium and phosphate of organisms. And yet excessive intake of fluoride produce potent toxicity to some systematical function of organisms. In the past, researches pay more attention to non-skeletal toxicity of fluoride, especially to reproductive toxicity induced by fluoride attaches importance on destruction of testis's structure, changes of sperm quality and disturbance of reproductive hormone. Few cross sectional study about fluoride reproductive endocrine disturbing effects had been reported and in reproductive endocrine disturbing effects. Since 1995 the experts of USA named the environmental endocrine disrupting chemical, the reproductive endocrine disturbing effects of fluoride was payed more attention in various studies. But there aren't on researches reported on endocrine disturbing of fluoride on hypothalamic-pituitary-testicular axis's systemic research, Therefore, it's significant to study the endocrine disturbing effect of fluoride, which could offer certain scientific basis to prevent and cure fluorosis. So, this study concluded cross sectional study and animal experiment.Part one cross sectional studyMaterials and Methods1 SunYing county, in Kaifeng city was selected as polluted plot where the average concentration of fluoride in drinking water was 3. 9 mg/L , and ShenLiLou county, also in Kaifeng city, was selected as the control plot where the average concentration of fluoride was less than 1.0 mg/L. Blood and urine samples were collected from 150 individuals who had lived there more than 5 years and were selected randomly. The serum level concentration of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), testosterone (T), and estradiol (E₂) in serum was measured useing RIA method, and the urine level concentration of fluoride in urine was measured using the same method. The concentration of fluoride in water, food, soil and air was measured using standard method.2 One-way analysis of variance (ANOVA), t-test and non-parametric tests were used in the statistical test. There was significant difference whenα=0.05.Results1 The concentration of fluoride in water in the fluoride polluted plot was significantly higher than that in the control plot (P<0.05).2 The serum level of GnRH in people of fluoride polluted plot was no-significant difference compared with the control group (P>0.05). The serum level of LH in men living in the fluoride polluted plot was significantly higher than that of the control group (P <0.05); and the serum level of T in men living in the fluoride polluted plot was significantly lower compared with the control group (P<0.05). The serum level of LH in women living in the fluoride polluted plot was no-significant difference compared with the control group (P>0.05); and the serum level of T in women living in the fluoride polluted plot was significantly higher compared with the control group (P<0.05). The serum level of E₂ in adults living in the fluoride polluted plot was no-significant difference compared with the control group (P>0.05).Conclusion1. Fluoride can affect hormone level of each layer of the hypothalamic-pituitary-testicular axis, and show the reproductive endocrine disturbing effect.2. The reproductive endocrine disturbing effects to male may be more severer than to female. Part two Animal experimentMaterials and Methods1. 36 healthy male rats weighted 65 to 75 gram were divided into 6 groups randomly. Each group had 6 rats. The 6 experimental groups were control group, low-concentration fluoride A group, low-concentration fluoride B group, high- concentration fluoride A group, and high-fluoride B group. The NaF concentration of each group was 0 mg/ L, 30 mg/ L, 30 mg/ L, 100 mg/ L, 100 mg/ L, respectively.2. According to the above-mentioned experimental dose, each group was treated with NaF in the way of drinking for eight or sixteen weeks. Rats were killed immediately after exposure in all experimental groups. Both testis and epididymis were weighted for calculating their organic coefficient, and the sperm quality, the rates of sperm mobility and sperm aberration were analyzed. The concentration of serum testosterone (T), estradiol (E2), prolactin (PRL), follicle-stimulating hormone (FSH), interstitial cell stimulating hormone (ICSH), and gonadotropin-releasing hormone (GnRH) were measured by radio immunochemically method. The content of NaF in testis was measured by using fluoride selective electrode.3. One-way analysis of variance (ANOVA), t-test and non-parametric tests were applied in statistical test. There was significant difference whenα=0.05.Results1. There was difference between the control group and the fluoride treatment groups (P<0.05) in body weight. As to right testis weight, there was difference in control group compared with the fluoride treatment groups (P<0.05), and low-concentration fluoride groups and high-concentration fluoride treatment groups (P<0.05). Epididymide organic coefficient in fluoride treatment group were higher than that in control group (P>0.05).2. Compared with the control group, fluoride treatment group, the counts amount of sperm and the rates of sperm mobility in fluoride treatment group significantly increased (P<0.05); and the rates of sperm aberration in fluoride treatment group significantly decreased (P<0.05) ; compared with low-fluoride group, the sperm quality descreased significantly (P<0.05) . 3. The level of GnRH in fluoride treatment groups were significantly increased (P<0.05) compared with the control group, with the compared to low-concentration fluoride group , the levels of GnRH in high-concentration fluoride group was increased (P<0.05).4. The level of FSH in fluoride treatment groups was significantly increased (P<0.05) compared to control group, compared to low-concentration fluoride group, the levels of FSH in high-concentration fluoride group was increased (P<0.05).5. The level of ICSH in high-concentration fluoride treatment groups was significantly increased (P<0.05) compared with the control group, compared with the low- concentration fluoride group , the level of ICSH in high-concentration fluoride group was increased (P<0.05). the levels of ICSH is no-significant difference between control group and low-concentration fluoride group (P>0.05).6. The level of PRL in fluoride treatment groups was significantly increased (P<0.05) compared with the control group, compared with the low-concentration fluoride group, the level of PRL in high-concentration fluoride group was increased (P<0.05).7. The level of T in high-concentration fluoride treatment groups was significantly descreased (P<0.05) compared with the control group, compared with the low-concentration fluoride group, the level of T in high-concentration fluoride group was descreased (P<0.05).8. The level of E₂ in fluoride treatment groups was significantly increased (P<0.05) compared with the control group, compared with the low-concentration fluoride groups, the levels of E₂ in high-concentration fluoride groups was increased (P<0.05).9. Fluoride content of every experimental group in Testis was significantly higher than that of the control group (P<0. 05). Compared with the low-concentration fluoride group, the levels of testis fluoride in high-concentration fluoride group was increased (P<0.05).10. Compared with the control group, the microstructure of testis was normal relatively in experimental groups, but it disappeared and were loosened, the number of mature sperm was reduced in the fluoride treatment groups. Conclusions1. Fluoride could affect hormone levels layer of the hypothalamic-pituitary-testicular axis,and show the male reproductive endocrine disturbing effects.2. Fluoride show the male reproductive endocrine effects with relation to the NaF dose.3. Fluoride show the male reproductive endocrine effects with no relation to the exposuretime.