Biology session

Growth factors are a signalling protein family, which stimulates cell growth, proliferation and differentiation. They are produced in a significant amount in the preimplantation period that suggests that they may play an important role in implantation processes. The heparin-binding epidermal growth factor (HB-EGF) reaches its expression peak 5-8 days after the ovulation in uterus epithelial cells. It suggests that this growth factor can play an important role in regulating blastocyst implantation as well. Due to the antiapoptotic effect of pituitary adenylate cyclase activating polypeptide (PACAP) and its widespread presence in the organ system, PACAP is considered as a general cytoprotective peptide. The peptide was found in the gonads in high levels, that is what drew attention to the peptide might play a central role in reproduction.

Due to the important role of HB-EGF in implantation and the widespread presence and cytoprotective effect of PACAP, the aim of our study is to assess the detectability of these two peptides in uterine tissue and embryo, their possible relation and their effects on the development of the embryos.

Our investigations were carried out on BDF1 mouse strain. Female mice were superovulated (7.5 IU eCG i.p., followed by 7.5 IU hCG i.p. 48 hours later). After the hCG injection the females were paired with males for a night. The zygotes were collected on the 4th day after the mating, along with a 0.5 cm uterus tissue. After determining the embryos’ development stages, we excreted RNA from the embryos and from the uterus tissue as well. After the cDNA synthesis we determined the amount of HB-EGF and PACAP with PCR.

The undeveloped, few - cell - embryos contained lower amounts of HB-EGF than the embryos in morula and blastocyst development stage. This explains the assumption that more HB-EGF is produced in embryos directly before the implantation. Furthermore, PACAP could not be detected in blastocyst and less developed embryos, due to its presumably low quantity.