Optimization of superovulation induction by human menopausal gonadotropin in guinea pigs based on follicular waves and FSH-receptor homologies.
The guinea pig represents an excellent animal model for the study of reproduction in humans and most domestic animals because unlike the mouse and rat, it undergoes a complete estrous cycle. In this study, we investigated the availability of ovarian oocytes during the estrous cycle, and the follicle stimulating hormone (FSH) receptor (FSH-R) homologies between guinea pigs and other species, in order to identify an effective gonadotropin and optimal time-of-application for the induction of superovulation in the guinea pig. The number of collectable ovarian oocytes showed biphasic changes with peaks at the midluteal and pre-ovulatory stages. On the other hand, the number of oocytes that matured in vitro remained constant ( approximately 10 oocytes) until day 14 post-ovulation and increased thereafter. The deduced amino acid sequence of the guinea pig FSH-R showed greater similarity to the primate FSH-R than to the rodent FSH-R, which suggests that commercially available human menopausal gonadotropin (hMG) may be a better inducer of superovulation in guinea pigs. Indeed, significantly more oocytes (5.4 +/- 1.6, range 0-17, n = 10) were obtained from hMG-treated guinea pigs at the pre-ovulatory stage than during spontaneous ovulation (3.6 +/- 0.1, n = 96; P < 0.05), whereas guinea pigs that received hMG at the midluteal stage (n = 3) did not ovulate. These results indicate that hMG is an effective, albeit stage-dependent, inducer of superovulation in the guinea pig, and that FSH-R homologies should be taken into account when choosing hormones for superovulation.
Suzuki
Osamu
O
Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan. osuzuki@nih.go.jp
Koura
Minako
M
Noguchi
Yoko
Y
Takano
Kaoru
K
Yamamoto
Yoshie
Y
Matsuda
Junichiro
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005260:Female; D005640:Follicle Stimulating Hormone / Q000235:genetics* / Q000378:metabolism; D006062:Gonadotropins / Q000008:administration & dosage / Q000494:pharmacology*; D006168:Guinea Pigs; D006801:Humans; D007267:Injections; D008969:Molecular Sequence Data; D006080:Ovarian Follicle / Q000187:drug effects*; D011372:Progestins / Q000494:pharmacology*; D011962:Receptors, FSH / Q000235:genetics* / Q000378:metabolism; D013480:Superovulation / Q000187:drug effects / Q000378:metabolism*
D006062:Gonadotropins; D011372:Progestins; D011962:Receptors, FSH; D005640:Follicle Stimulating Hormone