The Expression And Regulative Mechanism Of Liver Hepcidin During Different Stage Of Pregnance And Lactation On SD Rats

Iron, which is widely involved in the body’s metabolic processes, such as the electron transfer, oxygen transportation and the synthesis of ATP, plays an important role in the blood-oxygen transportation and maintaining the body functions. The liver and spleen, which are the essential organs of iron storage, are of importance in the iron metabolism. With further research, the molecules associated with the iron transportation in liver have been being discovered successively, such as the transferrin receptor (TfR) and divalent metal transporter protein (DMT1) related to iron uptake, ferroportin 1 (FPN1), ceruloplasmin(Cp) and Hp related to iron release, and ferritin related to iron storage. Pregnancy and breast-feeding are really the important physiological processes in women’s life, and it will have a great impact on iron metabolism. What the previous reports focused on are the blood test and the changes in serum ferritin test, therefore there will be a shortage in the research of regulatory mechanism of iron metabolism. With the discovery of the significant iron regulatory protein-hepcidin and the deepening research about how hepcidin regulate iron metabolism in the body, it has laid a foundation for us to better understand the regulatory mechanism of pregnancy and lactation in the iron metabolism.In this study, we conduct the experiments by using different gestational aged and lactating female SD rats, which were randomly divided into several groups:female control group (no pregnancy, NP), pregnant female group within 9 days (9 days pregnancy,9dP), pregnant females within 18 days (18 days pregnancy,18dP), lactating group within 1 day(1 day lactation, 1dL), lactating group within 7days (7 days lactation,7dL), lactating group within 14 days (14 days lactation,14dL), and lactating group within 21 days (21 days lactation,21dL). We determined the level of iron in serum and the amount of non-heme iron in liver. Through RT-PCR and Western-blot, we detect the variation of expression of hepcidin mRNA, EPOR mRNA in liver and the expression of iron transportation protein TfR2, P-ErK, TfR1, Ferritin-L, DMT1, FPN1 and Cp in liver and spleen.Results:1. The iron level determination in Serum and the result of transferrin saturation measurement show that compared with the NP group,9dP group,18dP group,1 dL group,7dL group,14dL group, and 21dL group have a higher iron levels and transferrin saturation in serum in varying degrees.2. Compared with the NP group, the non-heme iron levels in liver of 9dP group increased dramatically while decreased significantly in 18dP group; 1dL group,7dL group,14dL group, and 21dL group have a much low level of non-heme than that in the NP group. With the extension of breast-feeding, the non-heme iron levels in liver of 1dL group,7dL group,14dL group, and 2ldL group began to rise slowly.3. Detecting the expression of hepcidin mRNA in liver by RT-PCR showed that compared with the NP group, the expression of hepcidin mRNA in 9dP group increased obviously while decreased significantly in 18dP group, 1dL group and 7dL group. The liver’s content of EPOR mRNA in 18dP group, 1dL group and 7dL group reached a higher level than that in NP group.Detecting the variation of TfR2 and P-ErK by western blot showed that compared with the NP group, the amount of TfR2 during pregnancy represented the tendency that it increased at first and then declined while the amount of P-ErK during pregnancy in each group show off an opposite trend. However, with the exception of 7dL group, the expression of P-ErK decreased.4. The expression of iron transportation protein in liver and spleen detected by western blot demonstrated that the level of Ferritin-L ascended in 9dP group, which was clearly different from others’group, compared with the NP group. Its level returned to normal in 21dL group. The expression of TfR1 in liver and spleen maintained at a low standard. But interestingly, it reached a high standard in every lactating group, especially in 7dP group.The content of Cp increased dramatically in each group without exception. The DMT1 (+IRE) in spleen performed a similar currency with Cp in pregnant group and there was not any variation in lactating groups. And to our surprise, in liver, we detected no changes. It’s really obviously distinctive in each lactating groups, whose DMT1 (+IRE) level did increase. At last, we could get the result that the FPN1 in liver and spleen increased in varying degrees through the determination of FPN1. Conclusions:1. The iron level increase on the 9th day after pregnancy and decline continuously during the late pregnancy and lactation.2. The downward level of hepcidin in pregnancy and early lactation result from the EPO, and TfR2 is involved in the reduction process of hepcidin during pregnancy and lactation. It’s the first time to put forward a distinctive regulatory mechanism of hepcidin during pregnancy and lactation.3. Cp may be involved in the process of iron released in the liver and spleen during pregnancy and lactation. The iron uptake is mainly through the classical way of Tf-TfR. The DMT1 (+IRE) plays a role in liver’s iron uptake during lactation.The experiment studied the pregnancy and lactation which exert an influence on body’s iron metabolism on molecular level for the first time. Therefore, we proposed a different mechanism of hepcidin regulation in pregnancy and lactation and the mechanism of iron uptake and release. Also, these studies provide an experimental and theoretical basis for the future research to obtain a more comprehensive understanding of the abnormal iron metabolism in pregnancy and lactation.