| Lipids are one of essential elements in animal bodies. Under different conditions, the physiological functions of the tissues and organs are affected by the metabolism of lipids in cells. The synthesis, modification and degradation of lipids are influenced through various factors, including the changes of energy supply, integrity of membrane, the transduction of signaling molecules, the regulation of hormones and cytokines, and the alterations of external environment. Cellular homeostasis of lipids plays a crucial role on cell survival, as excess fatty acids(FAs) can damage cells. To prevent against lipotoxicity, cells are able to transfer excess fatty acids to neutral lipids and store them in organelles called lipid droplets. These organelles are not only involved in the storage and metabolism of lipid, but also in the transduction and transport of protein signaling, the formation of several hormones, the biosynthesis of membranes, cholesterol homeostasis and so on. Recently, the major focus of lipid droplets research is on the regulation of metabolism of lipids in LDs by lipophagosomes.Autophagosomes, a multifunctional organelle, play a key role on the maintenance of cellular homeostasis. It functions mainly as an intracellular "scavenger" that can clear the degradation of proteins, the aging cells and invading pathogens. Uterine cervix is not only housekeeper protecting fetus in gestational sac from the external environment, but also inevitable canal of foetal expulsion during parturition. In addition, the constriction and dilation of the cervix is a process of active consumption of energy involved in lipid droplets and autophagosomes.In order to explore their distribution and correlation of lipid droplets and autophagosomes in mice cervices, mature mouse cervices are collected during different reproductive periods,respectively. Immunolocalization of the LC3 and Atg5 protein and were measured by Immunohistochemical(IHC) method, and lipid droplets by Oil Red O with LC3 and Atg5 IHC in mice cervical tissues during the peripartal period are localized. Specificity of rabbit polyclonal anti-human LC3 and Atg5 antibody is assayed through Western Blot at parturition,nonpregnancy, and pregnanay. The relative expression levels of LC3, Atg5, and PPAR??mRNA in mice cervical tissues are determined by RT-PCR. The distribution and size of lipid droplets and autophagosome in the cervix was observed by the transmission electron microscope. The results show that the correlation between lipid droplets and autophagosome exists in the cervix of mice during different period. Immunohistochemical IOD analysis of LC3 and Atg5 in the mice cervix(paraffined section) during different reproductive periods extremely significant differences between the two(P< 0.01). The result and analysis of LC3 and Atg5 protein relative values in mice cervix during different reproductive periods.The expression levels of autophagy proteins during the various reproductive stages are similar to expression of LDs proteins at relatively various stages, extremely significant differences between the two(P< 0.01). What's more, at nonpregnancy, larger and light grey lipid droplets are mainly clustered in inferior part of the nucleus in the first layer of epithelial cells in cervix observed under the electron microscope. In the middle of pregnancy, dark gray lipid drops with the largest number are mainly clustered in the apical part of epithelial cells at the first layer, some out of cavity epithelium. Lipid droplets during parturition are also smaller, dark or light grey, gathered in the canal epithelium cells in the first layer. The maximum amount of expression levels of LDs is in the middle of pregnancy, in turn, at parturition, and nonpregnancy. These results indicate that larger energy may be consumed for a strong constant constriction of uterine cervix during pregnancy than for acute dilation of the cervix during delivery, and to minimum energy consumption at nonpregnancy. Increased expression of autophagosome proteins could be implicated in cleaning up of more fatty acids from lipid drops by autophagy, playing an important role on the prevention of cellular fatty acid poisoning. |
PDF Full Text Request