gonadotropin-releasing hormone (gnrh)

Gonadotropin hormone-releasing hormone (GnRH) is a peptide involved in mammals’ fertility and may also serve as a candidate target for cancer immunotherapy. Immunonsterilization is known as a proper alternative to surgical castration and has been advocated by European countries in recent years. Immunization with GnRH can effectively inhibit the secretion of gonadotropins and cause infertility in both genders of mammals. In this study, a recombinant trimer of GnRH is designed and expressed in a prokaryotic system.  A construct containing GnRH trimer was designed and prepared using gene synthesis. A cloning site was embedded and connected to the GnRH using a linker to further clone any protein of interest. The construct was subcloned into a pET-32a+ plasmid vector. The recombinant vector was transferred to BL21, an Escherichia coli strain, and the expression was induced using isopropyl β- d-1-thiogalactopyranoside (IPTG). The cell lysate was prepared using lysis buffer and nickel affinity chromatography purification. The GnRH expression was evaluated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis after protein purification. The cloning was verified using a polymerase chain reaction (PCR) followed by sequencing the recombinant vector. The result of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis verified the recombinant protein’s expression and the purification process’s function. The GnRH was properly cloned and expressed in BL21. The results also verified the reliability of the purification process. The construct design allows the researchers to express another peptide sequence attached to the GnRH using the embedded linker to improve the stability and antigenicity. A stable recombinant GnRH would be applied in immunocastration and cancer immunotherapies.

Follitropin alfa (FA) is one of the most widely used exogenous gonadotropins in both agonist and antagonist protocols for controlled ovarian stimulation (COS) and in vitro fertilization (IVF). However, reports of its effectiveness are limited, particularly in terms of its impact on overall IVF outcomes and ovarian hyperstimulation syndrome (OHSS). Therefore, in this study, FA competency was investigated by evaluating its effect on IVF outcomes and OHSS, administering agonist and antagonist COS protocols.

A retrospective study with 120 subjects was conducted. Outcomes comprising the number of retrieved and fertilized oocytes, quality of embryos, and clinical pregnancies were assessed. Statistical correlation between FA dose, IVF outcomes, and the incidence of OHSS was also analyzed. All statistical analyses were performed at 95% confidence level.

There was no significant difference in both protocols regarding retrieved oocytes (p=0.604), fertilized oocytes (p=0.761), embryo quality including good, average, poor embryo (p=0.875, p=0.565, p=0.785), and clinical pregnancy (p= 0.844). However, FA doses in the agonist protocol were shown notably higher (p= 0.001). Negative correlations were also observed between FA dose and the number of retrieved oocytes (r=-0.255, p<0.01), fertilized oocytes (r=-0.296, p<0.01), and good quality embryos (r=-0.231, p<0.05).

Our study suggested that FA yields similar outcomes in both COS protocols, but agonist protocols require higher doses of FA and evaluation of its effect on OHSS is an important area of research for further investigation.

The purpose of the current study was to investigate the effect of coadministration of human chorionic gonadotropin (hCG) with gonadotropin releasing hormone agonist (GnRH-a) trigger (dual trigger) in high responders for fresh autologous cycles in order to investigate the pregnancy outcomes and rates of ovarian hyperstimulation syndrome (OHSS) in comparison to GnRH-a trigger alone.

A systematic search was performed in PubMed and Ovid MEDLINE from inception through February 2020. The included materials were case-control, cohort and, cross-sectional studies as well as clinical trials in which the outcomes of dual trigger with GnRH-a were compared for final oocyte maturation in high responders undergoing GnRH-ant cycles.

Five retrospective studies were included for this review. Three of the studies showed that the use of dual trigger versus GnRH-a trigger resulted in no statistically significant difference in rates of OHSS while achieving a statistically significant difference in favor of the dual trigger group in ongoing pregnancy rates, early pregnancy loss, and fertilization rates.

Currently, there is insufficient evidence to support improved clinical pregnancy rate, fertilization rate, live birth rate, and early pregnancy loss rate by the use of dual trigger versus GnRH-a trigger. Larger double-blind clinical studies are required to properly evaluate the efficacy of this protocol for use in high responders.