| Recently, the faster the modern industry developed the higher risk the industrial fluorosismade. This problem has become a serious public health issue to the mental and physical healthof exposed population. The accumulation of fluorine in body under long-term fluorideexposure puts the bone metabolism out of order, for fluoride load exceeds the bodycompensatory ability. Thereby, a chronic systemic disease with extensive bone hyperplasiasclerosis as the major performance was caused, but its reason was still not clear. Therefore, theinvestigation of factors and mechanism of body’s antagonist fluorine pathogenichas made theresearchers pay close attention on it in order to effectively control and prevent fluorine harm,.Osteogenesis activity and abnormal bone conversion have the same character of variouslesions of the fluoride bone injury. The regulation of related signal pathways in injury anddefense plays an important role in the development of fluoride bone injury. Signal pathway ofWnt/-catenin, as the key pathway, regulates the osteoblast differentiation and bone formation.Also, its activity can promote the osteoblast differentiation and increase bone formation. Asthe negative factors of Wnt/-catenin signal pathway, Sclerostin(SOST) andDickkopf1(DKK1) play an important role in bone metabolism. However, few publiscatiionson the role of SOST and DKK1in high Fluorine load have been reported. This study attemptsto analyze the relationship between the rats’ serum concentration of SOST and DKK1and therelated proteins of fluoride bone injury through the method of animal experimental, to analyzethe relationship between the development of fluoride bone injury and the serum concentrationsof SOST/DKK1/Runx2/ALP in different group and time, and to preliminarily explore thepossible mechanism of SOST/DKK1and provide a theoretical basis for the prevention andtreatment of fluoride bone injury. Part The study of relationship between response of fluoride boneinjury index and fluorine dose in SD ratsObjective To establish a rat model of fluoride bone injury by drinking, and to explore thedose-response relationship between the incidence of fluoride bone injury and other indexthereby provide a scientific and accurate model basis for pathogenesis of fluoride bone injury.Methods64adult SD rats of SPF were randomly divided into low-dose group (1.6mg/kgNaF)、medium-dose group (16mg/kg NaF)、high-dose group (32mg/kg NaF) and controlgroup(0mg/kg NaF).The animal model of fluoride bone injury was made by adding fluoride indrinking water for SD rats. The dose was adjusted according to the daily body weight (mg/kg).Urine fluoride and blood fluoride was monitored every day in the process of building model,which was measured by micro determination of fluoride. Meanwhile, the ALP was also testedby automatic biochemical analyzer. At last, the dental fluorosis was documented with digitalcamera, and diagnosis and indexing depending on the standards of dental fluorosis accordingto dental fluorosis digital photos.Results Sixteen rats in high fluoride group can be found of dental fluorosis of the belowincisor in the35thday after exposed to the fluoride,93.6%are type Ⅱof dental fluorosis. Allrats in the middle and low fluoride groups can be found of dental fluorosis of the below incisorin the90thday after exposed to the fluoride. Urinary fluoride in the high fluoride group was(8.48±1.19) mg/L and the middle fluoride group was (6.38±0.53) mg/L, which is higher thanthe control group (1.09±0.35) mg/L, and the difference was statistically significant(t=13.58，P<0.05; t=37.1, P<0.05). Serum fluoride in the high fluoride group was (0.251±0.05) mg/L,which is higher than the control group (0.086±0.08) mg/L, and the difference was statisticallysignificant(t=52.4，P<0.05). The activity of ALP in the high fluoride group was (216.43±34.43)U/L and the middle fluoride group was (218.02±42.81) U/L which is higher than the controlgroup (160.55±41.33U/L), and the difference was statistically significant(F=6.635，P<0.05).The study of correlativity analysis suggested that the fluoride concentration and the urinaryfluoride was positively correlated, the correlation coefficient r is0.924(P=0.038). The fluorideconcentration and the serum fluoride was also positively correlated, the correlation coefficientr is0.948(P=0.026). The fluoride concentration and the incidence of dental fluorosis was alsopositively correlated, the correlation coefficient r is0.983(P=0.017). The periosteum of rats in control and low fluoride groups was thin and smooth and was composed of single-deckosteoblast, blood vessel and so on. The cortex of bone was not observed to become thick. Theperiosteum and cortex of rats in high and middle fluoride groups was thicker and the quantityof osteoprogeniter cells was increase.Conclusion There is an evident dose-response between the incidence of dental fluorosis andthe dose. The higher dose was given, the shorter time was need for dental fluorosis occurrence;Given16mg/kg and32mg/kg of fluoride to rats everyday,14days and35days are required topromote the occurrence of degree of dental fluorosis and typical dental fluorosis respectively;Serum ALP in high-dose and medium-dose group was significantly higher than the controlgroup at35-day and90-day end, which prompted bone conversion acceleration andosteogenesis active in rats, the bone is the target organs of fluorine; The SD rats femoralcortical and periosteal become thickened in high-dose and medium-dose group at90-day end,and a growing number of bone grandmother cells can be seen in some part of bone cortex andperiosteum.PartⅡ The regulation of SOST/DKK1to Wnt/-catenin signalingpathway in fluoride bone injuryObjective To explore the role of SOST/DKK1in Runx2controlled by wnt/-catenin signalingpathway of fluoride exposed rats according to the expression of SOST、DKK1and Runx2inserm.Methods64adult SD rats of SPF were randomly divided into low-dose group (1.6mg/kgNaF)、medium-dose group (16mg/kg NaF)、high-dose group (32mg/kg NaF) and controlgroup(0mg/kg NaF). The detection of urine fluoride and blood fluoride is carried out by microelectrode determination, the ALP is tested by automatic biochemical analyzer and theexpression of the serm SOST/DKK1/Runx2were analyzed by ELISA. Then the relationshipsbetween SOST/DKK1and blood fluorine, ALP and Runx2etc fluoride bone injury index wereanalyzed. The data were analyzed by SPSS18.0.Results Serum SOST concentration in the high fluoride groups was (11.55±1.02)μg/L, lowerthan the control groups (12.91±0.59)μg/L, and the difference was statistically significant(F=4.460, P=0.007) in the35thday after exposed to the fluoride. Serum Runx2concentrationin the high fluoride groups was (120.42±12.40)μg/L, higher than the control groups(111.21±13.49)μg/L, and the difference was statistically significant (F=2.693，P=0.054) in the 35thday after exposed to the fluoride. Serum SOST concentration in the high fluoride groupwas (8.86±0.85)μg/L and the middle fluoride group was (9.37±1.31)μg/L, which is lower thanthe control group(12.45±1.33) μg/L, and the difference was statistically significant (F=34.318，P=0.000) in the90thday after exposed to the fluoride. Serum Runx2concentration in the highfluoride group was (116.76±15.66)μg/L, and the middle fluoride group was(104.82±16.19)μg/L, which is higher than the control group(89.62±7.15)μg/L, and thedifference was statistically significant (F=15.152，P=0.000). The study of correlativity analysissuggested that the serum SOST concentration and the Serum Runx2concentration wasnegatively correlated, the correlation coefficient r is-0.444(P=0.000). Serum DKK1concentration in the high fluoride groups was (10.58±1.47)μg/L, lower than the control groups(10.84±1.03)μg/L, but the difference was not statistically significant (F=0.359，P=0.783) in the35thday after exposed to the fluoride. Serum DKK1concentration in the high fluoride groupswas (7.22±1.76)μg/L, lower than the control groups (10.43±1.04)μg/L, and the difference wasstatistically significant (F=23.047，P=0.000) in the90thday after exposed to the fluoride. Thestudy of correlativity analysis suggested that the serum DKK1concentration and the SerumRunx2concentration was negatively correlated, the correlation coefficient r is－0.018(P=0.887) in the35thday after exposed to the fluoride and the correlation coefficient r is－0.370(P=0.002) in the90thday after exposed to the fluoride.Conclusions Given16mg/kg and32mg/kg of fluoride to rats for90days, the expression ofWnt pathways inhibitory factors SOST and DKK1became reducing, but the expression ofosteogenesis must factors Runx2and ALP became rising; There was an evident dose-effectbetween the expression of SOST/DKK1and the dose，the higher fluorine load the lowerexpression level of SOST/DKK1; Fluoride bone injury maybe related to the expression ofSOST/DKK1, whose expression level was reduced in high-dose and medium-dose group;Fluoride bone injury might relate to the promotion of the Runx2expression, which attributedto the negative regulation of the wnt/-catenin pathway based on the the reduction of SOST. |
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