The expression of certain notch signalling pathway members during early pregnancy in mice uterus

There are many factors that have roles at appropriate establishment and progress of mamallian pregnancy. After fertilization, the proper development of preimplantation embryo, implantation and decidualization acts a major role for setting up a succesfull pregnancy. These events happens at uterus that has heterogeneous cell types. The embryo that complete its preimplantation development properly is able to implant the receptive uterus that is prepared synchronised with preimplantive embryo. Notch signaling is an intercellular signalling pathway that is evolutionarily conserved and is involved in determination of cell fate and many cellular mechanisms. Notch signalling is activated by directly cell-cell contact and is required for organising of many biological function as apoptosis, cell proliferation, differentation, cell fate. The effects of Notch signalling pathway members on uterus receptivity and setting up decidualization at early pregnancy is not completely explained. In this study, it is aimed to analyse the distribution and the expression levels of the active Notch1 (NICD1), the active Notch2 (NICD2) and the target genes of Notch signalling pathway HEY1 and HES5 in the uerus on early pregnancy. To that end, the uterus tissues from estrus stage female mice, female mice at the 1st, 4th, 5th and 8th days of pregnancy are colected and fixed with 10% formaline and prepared for paraffin sections. The immunolocalisation of NICD1, NICD2, HEY1 ve HES5 proteins are determined on the sections that are 5-7 µm-thick via immunohistochemical method. It was observed that in early pregnant uterus NICD1 is generally expressed in the tissue and has higher levels on the 5th day of pregnancy synchronised with HEY1; the immunostaining intensities of NICD2 and HES5 are lower than NICD1 and HEY1; the experssion of NICD2 is increased on 5th day of pregnancy and is gathered on blastocyst and primary decidualization zone, on the 8th day of pregnancy its expression is increased on secondary decidualization zone, and also NICD2 is very intensively stained on mast cells that are exist in the uterus tissue of the female mice at the stage of estrus and gradually decreased on the 1st, 4th and 5th days of pregnancy. In conclusion, the members of Notch signalling pathway, NICD1 and HEY1 may be required for preparing the mice uterus for pregnancy, implantation and controlling the process of embryo development.