Presence of Antioxidant in in vitro Maturation Medium and its Effects on Glutathione Level, Spindle Area and Rate of in vitro Fertilization

Background: Effec t of diffe rent doses of cysteam ine on rateof in vitro maturation (lYM), in vitro fertili zati on (l YF) andglutathio ne (GSH) leve l was studied. Metaph ase II (MIl)spindle area was analy zed for quant ificat ion of shape ands ize of oocy tes.Methods: Female mice were primed with 5 IU of pregnantmare s stimulating gonado trophin. Germina l ves icle (GY)oocytes were ret rieved 48 hrs later. IYM medium was supplementedwith 0, 50, 100, 200 and 500 mM of cysteamine.For IYM and IYF asse ssme nt in each group, 150 GY oocyteswere used . Experiments also inc luded a gro up of ovulatedoocytes (matured in vi vo ) after prim ing with pregnan t mare sstimulating gonadotrophin and human ch or ionic gonado tropin. GSH level was measu red by 5,5-Dithio-bis(2nitroben zoic acid) DTNB-GR recyclin g protocol in GYand MIl oocytes. For IYF, Mil oocy tes were insemina tedwith mature mouse spe rm and rate of two-cell embryo wasmeasured . For immunocytochemi stry of microtubul e andchromoso mes, Mil oocy tes were fixed by methano l and immunostained with (L- and ~ - m icro t u bu le ant ibody andHoechst. The spindle area was then ana lyzed.Results: A dose-dependent improvemen t was obse rved inlYM and IYF rate. Mil developm ent and two-cell emb ryoformation were increased sign if icant ly in group which received200 urn cystea mine compare to the contro l gro up.GSH level was increased in presence of cys team ine in groupwhich received 200 urn cysteamine. Spindle area was increasedin all gro ups in vitro except for the group which received 500 urn cysteamine. The difference between spindlearea in 200 urn cys teamine and in vivo group was not s ignificant(P 0.05).Conclusion: Administration of cysteamine improves IYM andIYF rate in a dose-dependant manner. Also cysteami ne inducesglutathion e synthesi s in Mll oocyte and improvesmicrotub ule when administered at a dose of 200 urn. Therefore,addit ion of cysteamine as an antiox idant can improveIYM and IYF rate by increasing of oocytes qualit y.