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The pituitary adenylate cyclase-activating polypeptide (PACAP) is considered to be a general cell-protective peptide with anti-apoptotic activity. After the central nervous system, it is present in large quantity in the testis and throughout the female genital tract, suggesting a central role in reproduction.

The objective of our study is to investigate the effect of the exogenous peptide on embryo development and quality and to assess its potential applications in vitrification.

Our studies were performed in BDF-1 mouse strain. Female mice were superovulated (7.5 IU PMSG i.p., followed by 7.5 IU hCG i.p. 48 hours later) and after the hCG injection they were placed with males overnight. The zygotes were collected from the oviduct the morning after mating and cultured in vitro in G1 medium supplemented with different amounts of lyophilized PACAP for 96 hours. Then we determined their developmental stage, the blastocyst rate, cell count after SYBR14 fluorescent staining and micronucleus ratio. In our vitrification study, we divided the blastocyst stage embryos into five treatment groups. In two groups, 1 μM and 2 μM PACAP was added to the equilibration solution (VF1 and VF2), in two groups 1 μM and 2 μM PACAP was added to the culture medium after vitrification/thawing (IVC1 and IVC2), and in the control group, embryos were vitrified/thawed and cultured without any treatment. After 24 hours of in vitro culture, we examined the developmental rate in each group.

In our study, we observed a lower micronucleus ratio in the PACAP-treated groups compared to the control. Also, a significantly higher development rate was observed in embryos treated with higher doses of PACAP in the equilibration solution during vitrification (VF2) in contrast to the control group.

The present results show that PACAP improves the quality of embryos and makes them more resistant to the damaging effects of cryopreservation, thus promoting survival and development. Our studies may serve as a preliminary study on the applicability of PACAP in assisted reproductive procedures.