Effects of Anti-inhibin Free α Immunization on Ovulation, in Viro Fertilization, and Embryo Development in Mice

Inhibin is a dimeric glycoprotein comprised of two subunits, α and B. Immunization against dimeric inhibin is mainly used in assisted reproductive technology to induce superovulation. However, the specific function of immunoreactive-free inhibin α subunit remains unclear. In this study, two main investigations were conducted (first on ovulation and the other on fertilization) using a novel monoclonal antibody targeting free inhibin α subunit (Pro-αN-αC). The ovulation study was conducted in 6 replicates, involving a total of 48 female CD1 mice aged 4–6 weeks. In each replicate, 4 control mice received PMSG/hCG treatment, and 4 treated mice received PMSG/hCG with mAb- Free α subunit. The fertilization study was conducted in 3 replicates, involving a total of 22 female CD1 mice. In each replicate, there were 4, 3, and 4 mice respectively for both control and treatment groups. In both investigations, female mice were injected intraperitoneally with 50 units/ml of Pregnant Mare Serum Gonadotropin (PMSG), alone or combined with 400ug of mAb- Free α subunit, followed by an injection of 50 units/ml of Human Chorionic Gonadotropin (hCG) 48 hours later. Seventeen hours post-injection, the females from all groups were sacrificed, and the ovulated oocytes were collected from the oviducts. For the fertilization study, in vitro fertilization was performed using fresh sperm from male CD1 mice. The results revealed that neutralization of the free inhibin α subunit significantly decreased the ovulation rate by 47.29% compared to the control group, while immunoneutralization significantly increased the fertilization rate by 55.68% and the blastocyst development by 43.85% compared to the control group. This study suggests that immunization against free inhibin α subunit decreases ovulation, in contrast to the effect of immunoneutralization of dimeric inhibin. The authors hypothesize that the free α subunit may function as an inhibin antagonist, competing with inhibin for binding to its co-receptor.