Efficacy of native and hyperglycosylated follicle-stimulating hormone analogs for promoting fertility in female mice

Objective: To compare the efficacy of recombinant human FSH (rhFSH) with rhFSH with four additional O-linked carbohydrates (rhFSH-CTP), rhFSH with four additional N-linked carbohydrates (rhFSH-N4), and the current gold standard for rodent ovarian stimulation, pregnant mare serum gonadotropin (PMSG), on fertility parameters in mice. Design: Animal study. Setting: Academic research center. Animal(s): Adult C57B1/6J female mice. Intervention(s): Ovarian stimulation with 5 TU of rhFSH, rhFSH-CTP, rhFSH-N4, or PMSG. Forty-six hours later, 5 IU of hCG was injected to promote ovulation and females were mated overnight. Main Outcome Measure(s): Eggs retrieved after ovulation, in vitro embryo development, delivery rate, and litter size. Result(s): The hyperglycosylated FSH analogs, rhFSH-CTP and rhFSH-N4, enhanced ovulation and embryo maturation significantly better than rhFSH. RhFSH-N4 produced more eggs (28.5 +/- 1.9 per mouse) and embryos 1 (17.8 +/- 1.6) compared with rhFSH-CTP (18.3 +/- 1.2 and 9.0 +/- 1.0, respectively). Treatment with rhFSH, rhFSH-N4, and PMSG produced statistically equivalent delivery rates and litter sizes.. The delivery rate was surprisingly lower with rhFSH-CTP (14%) compared with PMSG (33%). Conclusion(s): Compared with rhFSH, treatment with hyperglycosylate rhFSH-CTP and rhFSH-N4 led to superior rates of ovulated eggs and subsequent in vitro embryo development. RhFSH-N4 was equivalent to PMSG, while all of the fertility parameters studied were lower with rhFSH-CTP than-with PMSG therapy. (Fertil Steril (R) 2009;91:265-70. (c) 2009 by American Society for Reproductive Medicine.)