The fertilization and development of mouse oocytes following cortical granule discharge in the presence of a protease inhibitor.
The effect of leupeptin, a serine protease inhibitor, on the fertilization and development potential of oocytes stimulated to undergo cortical granule exocytosis has been investigated. An in-vitro bioassay system was used in which mouse oocytes were exposed to calcium ionophore, A23187, in the presence and absence of leupeptin, before their fertilization and development to the blastocyst stage was assessed. We have demonstrated that the presence of leupeptin in the incubation medium, at concentrations of 1 micrograms/ml and 10 micrograms/ml during the first 10 min of cortical granule exocytosis, reversed the ionophore-induced decrease in the capacity of oocytes to fertilize and develop to blastocysts. The induction of exocytosis of cortical granules by calcium ionophore was confirmed using fluorescence microscopy. Using this technique, we also confirmed that leupeptin did not inhibit ionophore-induced cortical granule exocytosis, thus supporting the contention that leupeptin acted upon released cortical exudate. It was concluded that leupeptin acted by inhibiting proteases released into the perivitelline space during the early stages of cortical granule exocytosis. Based on these results it was proposed that leupeptin could be used to prevent premature loss of fertility of human oocytes which are inadvertently activated under in-vitro conditions.
Tawia
S A
SA
Department of Obstetrics and Gynaecology, University of Melbourne, Parkville, Vic., Australia.
Lopata
A
A
D000818:Animals; D001755:Blastocyst / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D046508:Culture Techniques; D004622:Embryo, Mammalian / Q000187:drug effects*; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005089:Exocytosis / Q000187:drug effects*; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D005307:Fertilization in Vitro; D005456:Fluorescent Dyes; D007315:Insemination, Artificial; D007976:Leupeptins / Q000494:pharmacology*; D051379:Mice; D009865:Oocytes / Q000187:drug effects*; D013480:Superovulation
D005456:Fluorescent Dyes; D007976:Leupeptins; D000001:Calcimycin; C032854:leupeptin