In order to investigate the influence of hypomethylation on the development of rat placenta at periimplantation period we used demethylating agent 5-azacytidine (5azaC). This was performed while bearing in mind that changing the proliferative ability of trophoblast cells could affect their potential role in the process of implantation. Single dose of 5azaC (5 mg/kg) was injected intraperitoneally in gravid female rats at days 4th and 5th of gestation. The animals were sacrificed during the 20th day of gestation, and placentas were prepared for immunohistochemical analysis using proliferating cell nuclear antigen (PCNA). We have analyzed the stereological variable of volume density (Vv), using Weible's multipurpose system with 42 test points. The statistical analysis of volume density comparing study and control group was performed using the Student’ s t test (p<0.01). The application of 5azaC on the day 4th caused the failure in development of the functionally most important part of the placenta – labyrinth. The volume density of the PCNA-positive trophoblast cells was statistically significantly larger than the control (p<0.01). The same result was obtained with placentas treated on the day 5th, but volume density was higher then not only in comparison with control but also with the 4th day (p<0.01). Observed changes of proliferative trophoblast cells volume density in the placenta after application of 5-azaC are consistent with our previous results obtained using another stereological variable of numerical density (Serman et al, 2007) and are another proof of the importance of epigenetic in regulation of development.

Temeljne medicinske znanosti