Studies On The Toxicology Of Chronic Fluofosis In Goat

In this paper,twelve goats were divided into two study groups.Group I was treated as control and group II were fed sodium fluoride(NaF) orally according to their bodyweight.After 12 months of fluoride dosing, goats of group IT showed clinical signs of fluorosis and all goats were euthanized and their tissues and blood samples were taken for analyses. The tissues, including brain,heart,liver,spleen, kidney, thyoid,testes,were treated for observation of the enzyme activity and pathological (including microscropic and ultramicroscopic) changes.Blood samples were separated for determination of the free radicals,antioxidant function, enzymes,cytokine and thyroid hormone.The principal focus of this study was to clarif~~ the mechanism of fluorosis and provide the theoretical and practical basis for making effectively and feasiblely comprehensive alleviation measure.The results and conclusions showed as follows:1.Animal models with pathological damage caused by chronic fluorosis were duplicated in goats by feeding them with NaF according to their bodyweight for twelve months.2.The molecular mechanism of fluorosis in goats is that fluorine induces excessive oxygen ,nitrogen free radical and lipid peroxides,disturbs the free radical metabolism,reduces the function of scavenging free radicals and antioxidant defense system in organism,which result in strongly oxidant stress ,furthermore ,injure the structure and function of all tissues and organs,damage the metabolism process and cause a series of pathological changes,which contribute to the pathogenesis of fluoride-induced injuries in goats.3.Fluoride decreased the content of inteleukin 2(IL-2) and inte]eukin 6(IL-6),increased tumour necrosis factor(TNF) significantly compared with the group I . These values suggest that fluoride reduces immune function and creates the conditions for various malignancies in fl uorosis.4.Fluoride injures the structure and function of thyroid ,disturbs the synthesis and secretion of throid hormone,and interferes with the regulatory system of thyroid. The fluorosis goats exhibited apparent evidence of hypothyroidism.5.The contents of modulate factors in bone metabolism,including calicitonin(CT) and osteocalcin(BGP) rose in group II .The result shows that the skeletal fluorosis is characterized by highly bone turning over .Fluoride can effect bone modeling and increases bone mass.6.Erthrocyte anti-oxidant function,ion pump function(ATPase),the contents of sialic acid(SA) and erythrocyte immune function were decreased due to excessive fluoride ingestion.A great number of erthrocyte deformed with polyhedral angel shape and star shape by the observation of scaning electronic microscope in group II . The results provide the valuable clue of the anemia mechanism in fluoride-mediated.7.Fluorosis plays significantly inhibitory roles in enzyme of non-skeletal tissues.8.Fluoride injures the structure and ultralstructure of thyroid,kidney , brain,etc.The machanism of fluoride-mediated injuries in non-skeletal tissues is that fluoride results in disorder of free radical metabolism,that excessive free radicals and LPO in organism damage tissue and cell biological membrane structure and the metabolism of biological molecular therefore,the structure and function of non-skeletal tissues are abnormal.