Assessing The Effectiveness of Growth Hormone Releasing Protein-6 in Improving Human Oocyte Maturation and Meiotic Progression in In Vitro Maturation Culture Media.

Background: The success rate of in vitro maturation (IVM) for human oocytes is clinically significant, prompting a focus on optimizing IVM media culture. While various factors have been incorporated to improve outcomes, the role of Ghrelin hormone, despite its multifunctional nature, remains poorly investigated. This study aimed to determine the most effective concentration of the growth hormone releasing protein-6 (GHRP-6), Ghrelin hormone agonist, in the culture medium.

Materials and methods: In this experimental study, a total of 240 human germinal vesicle (GV) oocytes were collected and cultured in varying concentrations of GHRP-6. Maturation rates were assessed during two days of culture, and compared against a blastocyst media (single-step culture) as control group and another IVM media, human tubal fluid (HTF) 10%, as the sham group. Additionally, the expression levels of two genes associated with nuclear and cytoplasmic maturation were compared in the number of 164 GV oocytes randomly cultured in the most effective concentration of GHRP-6, control and sham groups for 24 hours, using real-time polymerase chain reaction (PCR).

Results: The optimal concentration of GHRP-6 for the IVM procedure was determined to be 75 ng/ml, resulting in a maturation rate of 70% on the first day and 80% on the second day. These results surpassed those of other culture media on both days. Real-time PCR data indicated that, despite the early appearance of the first polar body (PB1) on 24h of culture, the Ghrelin agonist did not elevate the expression levels of CENP-E or LINGO2, genes associated with meiotic progression and membrane proteins, respectively.

Conclusion: In summary, while GHRP-6 showed potential in promoting nucleonic maturation by significantly inducing the appearance of PB1 between GVs within 24 hours, it did not exhibit statistically significant improvements in cytoplasmic maturation in metaphase 2 oocytes (MII) during this timeframe.