Rat embryo quality and production efficiency are dependent on gonadotrophin dose in superovulatory treatments

Abstract

SummaryThe present study was performed to optimize a superovulation protocol in rats in order to produce a large number of good-quality embryos suitable to develop rat embryonic stem (rES) cells. We first evaluated the ovulation kinetics of three rat strains: Wistar, Fisher and ACI/N. Animals (n ¼ 30 per strain) were treated with 50 IU of pregnant mare serum gonadotrophin (PMSG), and ovulation was induced with 50 IU of human chorionic gonadotrophin (hCG) 50 h apart. Next, we evaluated the dose-response curves of PMSG and hCG in Wistar rats in order to obtain the highest number of embryos. The parameters evaluated for superovulation efficiency were: percentage of mated females, percentage of pregnant females and the average number of embryos collected per female. The results of these experiments suggested that the best dose combination was 50 IU for each hormone. Subsequent experiments, again with Wistar rats, were designed to test which of four hormonal combination treatments (30/30, 30/50, 50/30, and 50/50 IU of PMSG/hCG) will produce the largest numbers of good-quality embryos. Embryo quality was evaluated by embryo development uniformity, embryo morphology, embryo survival in an in vitro culture and embryo ability to generate rES-like cells. Results from these experiments showed that 30/50 IU of PMSG/hCG was the treatment that induced the best embryo quality. In conclusion, our results indicated that, in Wistar rats, the most appropriate hormonal combination dose for superovulation protocols with high number of good-quality embryos was 30 IU of PMSG and 50 IU of hCG given 50 h apart. We are performing further studies with rES-like cells produced with the present methodology to evaluate if they are able to participate in the production of germ-line chimeras.

Effects of melatonin on the endometrial morphology and embryo implantation in rats

“…Intraperitoneal administration of gonadotropins in prepubescent, 10-to 12-week-old females induces ovulation with an average production of 30 oocytes per animal. Initially, each female was injected with 30 IU of pregnant mare's serum gonadotropin, which mimics FSH, and, after 42-48 hours, with 50 IU of hCG, which in turn mimics the LH peak (18,19). This hormone matures the follicles and induces the discharge of oocytes from the ovaries into the oviduct.…”

Fertilizability of Superovulated Eggs by Estrous Stage-independent PMSG/hCG Treatment in Adult Wistar-Imamichi Rats

“…According to Kagabu’s [16, 18] and our previous [20] data, efficient superovulation can be induced for at least eight weeks (10–18 weeks of age) in adult, whereas efficient superovulation can be induced for only two weeks (4–6 weeks of age) in immature rats. In comparison with other strains [1, 2, 4, 6, 19, 28], WI rats are superior to other strains in the number of obtained eggs. In addition, WI rats are also superior to other strains in handling.…”

“…There are various methods to induce superovulation in laboratory rats, such as injection of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) [1, 2, 4, 12, 22, 25], continuous infusion of follicle stimulating hormone [5, 30], and injection of inhibin antiserum [14, 15]. Among these methods, PMSG/hCG treatment is widely used as a simple and effective method to induce superovulation [4, 28]; however, it is known that response to PMSG/hCG treatment varies by strain [1, 4, 6, 19, 20, 22, 25, 28] and with age [16, 18,19,20, 22, 28].…”

“…Of note, the fertilization and developmental ability of the obtained eggs were not investigated in the previous study [20]. There are several reports that the fertilization and developmental ability of eggs obtained from PMSG only- or PMSG/hCG-treated rats are low in other strains [2, 3, 31, 32]. Therefore, we determined the fertilization and developmental ability of superovulated eggs obtained from PMSG/hCG-treated adult WI rats after natural mating with adult males, and using in vitro fertilization (IVF) and embryo transfer (ET).…”

Blastocysts production and collection in albino syrian hamster using superovulation and intraute­rine artificial insemination in non-breeding season

“…Embryos have been produced with various injection interval timing of hormones (PMSG and hCG) in different rodents, such as 50 h interval in rats (Cornejo-Cortes et al, 2006), 48 h interval in mice (Ertzeid & Storeng, 1992) and 56 h interval in hamsters (Lee et al, 2005).…”