Effects of supplementation with free radical scavengers on the survival and fertilization rates of mouse cryopreserved oocytes.
BACKGROUND
This study was conducted to investigate the effects of supplementation with free radical scavengers on the survival and fertilization rates of freeze-thawed mouse oocytes.


METHODS
Superovulated oocytes with cumulus cells were cryopreserved by slow freezing in propanediol combined with a rapid thawing protocol. The cryopreservation medium was supplemented with the antioxidant enzymes superoxide dismutase (SOD) and catalase, and with the nitric oxide (NO) scavenger, haemoglobin (Hb).


RESULTS
The addition of 50 IU/ml SOD showed significantly higher survival and fertilization capabilities compared with control (P < 0.01). Oocyte survival was greatly increased by concomitant addition of SOD with 10 IU/ml catalase (P < 0.01). On the other hand, the NO donor (sodium nitroprusside) inhibited survival and fertilization rates (P < 0.05). Significantly decreased survival and fertilization rates were also observed following the addition of high concentrations (10(-3) to 10(-6) nmol/l) of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). In contrast, significantly better oocyte survival and fertilization rates were detected with low concentrations (10(-7) nmol/l) of L-NAME. Oocyte survival potential was significantly increased by addition of Hb (1 microg/ml, P < 0.05). Moreover, oocyte survival and fertilization rates were significantly promoted by the concomitant addition of SOD with Hb (P < 0.01).


CONCLUSIONS
These results suggest that supplementation of free radical scavengers, particularly combinations of SOD with NO scavengers in freezing and thawing media, improved the post-thaw survival and fertilization rates of cryopreserved mouse oocytes.
Dinara
S
S
Department of Obstetrics and Gynecology, Midorigaoka Higashi 2-1-1-1, Asahikawa 078-8510, Japan.
Sengoku
K
K
Tamate
K
K
Horikawa
M
M
Ishikawa
M
M
D000818:Animals; D002374:Catalase / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D015925:Cryopreservation; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005306:Fertilization / Q000187:drug effects*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006454:Hemoglobins / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology*; D013482:Superoxide Dismutase / Q000494:pharmacology
D004338:Drug Combinations; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D006454:Hemoglobins; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D002374:Catalase; D013482:Superoxide Dismutase; D019331:NG-Nitroarginine Methyl Ester