Study On The Thyroid Disrupt Of Amphibian

The studies indicated that some of environmental matters posses endocrine disrupter activity, in which a type of them can disturb the structure or function of thyroid system, which were named as thyroid disrupting chemicals (TDCs). Due to the importance of thyroid system played in the growing development, esp. in the growing of nervous system, the ecology and health risk of TDCs received much concerns.The morphology, structure, cell, biochemistry and molecule as well as all levels change during the metamorphosis process can reflect the statue of thyroid gland system, as a result of the amphibians goes through the metamorphosis development process that are adjusted by thyroid hormone. Nevertheless, the metamorphosis development of amphibians was regarded as good model of researching the thyroid disrupt effect. At present, most of study take Xenopus laevis to research the thyroid disrupt effect on the amphibians model. On the other hand, because of the sensibility of the amphibians for the thyroid disrupts effect, the thyroid disrupts effect and its ecology risks of TDCs for the amphibians are remarkable. R. nigromaculata is the representatives of the amphibians which is widely distributed in our country, compared with Xenopus laevis that is low species during evolution, there is a huge difference between the biological characteristics of them is. Thus, the data of thyroid disrupt get from the Xenopus laevis studies cannot be directed applied in the R. nigromaculata. Therefore, it is necessary to study the thyroid disrupts effect and ecology risks of our native amphibian R. nigromaculata that was influence by the thyroid disrupt.Perfluorooctane sulphonates (PFOS) is characterized as hydrophobic and lipophobicity, usually are used as surface active agent. It is listed as banded substance by Stockholm Convention on Persistent Organic Pollutants, but is still widely existed in the environment. Currently, PFOS substituent, such as Perfluorobutane sulfonates (PFBS) has been started to use. Researches show that high dose PFOS are thyroid disrupt, but we still have no idea of whether environmental dose of PFOS and PFBS are thyroid disrupt. Xenopus laevis was used to study the thyroid disrupt effect of PFOS and PFBS. Xenopus laevis at NF46/47stage were exposed to environmental dose (0.1,1,100,1000μg/L). The results showed that PFOS and PFBS did not affect the thyroid of Xenopus laevis under the environmental dose (0.1,1,100,1000μg/L)by using the metamorphosis time, thyroid organization, thyroid hormone (TH) content and thyroid related gene mRNA express as endpointsPreviously, there were several biological studies of R. nigromaculata. However, the developing process and secrete regulations of thyroid system of it still do not know. Therefore, this paper systematically studied the developing organization of thyroid and changes of TH. The lower jaw of R. nigromaculata at Gosner26-46stage was sampled to study the histological structure of thyroid gland. The lower brominated substances in the polybrominated diphenyl ethers(PBDEs) were listed as banned substance by Stockholm Convention on Persistent Organic Pollutants, but decabromodiphenyl ether (BDE-209) is still widely used. Several investigations showed lower brominated BDEs had much higher thyroid disrupting effects than higher brominated BDEs. However, the thyroid disrupting effects of BDE-209for amphibian is still not clear. In this study, R. nigromaculata at Gosner26to42stage were exposed to environmental dose (0.1,1,10μg/L) by using the metamorphosis time, thyroid histological structure, TH content and thyroid related gene mRNA expression. The results showed that low dose BDE-209(0.1,1μg/L) exposure could promote the thyroid development, while high dose will (10μg/L) suppressed it.