Developmental and Molecular Effects of C-Type Natriuretic Peptide Supplementation in In Vitro Culture of Bovine Embryos.

The use of C-type natriuretic peptide (CNP) in the interaction with the oocyte and in the temporary postponement of spontaneous meiosis resumption has already been well described. However, its action in pre-implantation developmental-stage embryos is yet to be understood. Thus, our study aimed to detect the presence of the canonical CNP receptor (natriuretic peptide receptor, NPR2) in germinal vesicle (GV)-, metaphase II (MII)-, presumptive zygote (PZ)-, morula (MO)-, and blastocyst (BL)-stage embryos and, later, to observe possible modulations on the embryos when co-cultured with CNP. In Experiment I, we detected and quantified NPR2 on the abovementioned embryo stages. Further, in Experiment II, we intended to test different concentrations (100, 200, or 400 nM of CNP) at different times of inclusion in the in vitro culture (IVC; inclusion from the beginning, i.e., day 1, or from day 5). In Experiment III, 400 nM of CNP was used on day 1 (D1) in the IVC, which was not demonstrated to be embryotoxic, and it showed potentially promising results in the blastocyst production rate when compared to the control. Thus, we analyzed the embryonic development rates of bovine embryos (D7) and hatching kinetics (D7, D8, and D9). Subsequently, morula and blastocyst were collected and evaluated for transcript abundance of their competence and quality (apoptosis, oxidative stress, proliferation, and differentiation) and lipid metabolism. Differences with probabilities less than