Development of a hamster superovulation program and adverse effects of gonadotropins on microfilament formation during oocyte development.
OBJECTIVE
To establish a superovulation procedure for the golden hamster (Mesocricetus auratus) by elucidating gonadotropin effects on oocyte development.


METHODS
Randomized, prospective study.


METHODS
University laboratory of embryology and gamete biotechnology.


METHODS
Twelve- to 15-week-old female and sexually mature male hamsters.


METHODS
Different doses of pregnant mare serum gonadotropin (PMSG) were injected into female hamsters in metestrus, diestrus, or proestrus. The same dose of hCG was injected 56 hours later.


METHODS
Embryo development and oocyte morphology after treatment.


RESULTS
First, 10 IU or 15 IU each of PMSG and hCG was injected into 10 hamsters weighing <110 or 110-130 g, respectively. All hamsters were mated, but none delivered live young after injection. Second, the doses of 15 IU, 7.5 IU, 5 IU, or 0 IU of each gonadotropin were injected into each hamster (regardless of body weight, 5 per each group). Increasing numbers of embryos were retrieved as the dosage was increased (11.2 to 46.6 embryos per hamster), whereas the percentage of two-cell embryos at retrieval was significantly decreased (100% to 3%, P<.05). In subsequent culture, none developed to blastocysts after 15-IU injection, whereas 47%, 55%, and 70% of two-cell embryos developed after 7.5-IU, 5-IU, and 0-IU treatments, respectively. As a result, females injected with 5 IU yielded more blastocysts than did females without injection (67 vs. 39). The number of inner cell mass cells per blastocyst was greatly increased in the control groups compared with the 5-IU and 7.5-IU treatment groups (22 vs. 14.3-14.7 cells per blastocyst). Third, the ultrastructure of oocytes was examined after injecting 5 IU each of PMSG and hCG (regardless of body weight). Superovulation did not affect oocyte maturation, but different patterns in microfilament formation were detected after the treatment.


CONCLUSIONS
Female hamsters can be superovulated effectively by injecting equal amounts of PMSG and hCG, 56 hours apart. However, embryo development was adversely affected in a dose-dependent manner at all doses of gonadotropins, and microfilament distribution was affected by such treatment.
Lee
Seung T
ST
Division of Animal Genetic Engineering, School of Agricultural Biotechnology, Seoul National University, Sillim-9 Dong, Seoul 151-742, South Korea.
Kim
Tae M
TM
Cho
Mi Y
MY
Moon
Shin Y
SY
Han
Jae Y
JY
Lim
Jeong M
JM
D008841:Actin Cytoskeleton / Q000187:drug effects*; D000818:Animals; D001835:Body Weight; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D006224:Cricetinae; D004031:Diestrus; D047108:Embryonic Development / Q000187:drug effects; D004971:Estrus; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D008297:Male; D008647:Mesocricetus; D008686:Metestrus; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D010062:Ovulation Induction / Q000009:adverse effects / Q000379:methods*; D011359:Proestrus
D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine