C57BL/6J mouse superovulation: schedule and age optimization to increase oocyte yield and reduce animal use

Abstract

Superovulation protocols have been described for different mouse strains, however the numbers of animals used are still high and still little information is known about hormone administration schedules and estrous cycle phases. In this study, we aimed to optimize a superovulation protocol by injecting 5 IU of pregnant mare serum gonadotropin followed by 5 IU of hCG 48 h later, using three different schedules related to the beginning of the dark cycle (3, 5 and 7 pm) in a light cycle of 7 am to 7 pm, with light on at 7 am. C57BL/6J mice at 3, 4 and 5 weeks of age were used and the estrous cycle phase for times of PMSG and hCG injections was also analyzed. Total oocyte number was counted in the morning after hCG injection. Hormones given at 3 weeks of age at 3 pm (59 ± 15 oocytes) and 7 pm (61 ± 10 oocytes) produced a significantly higher oocyte number compared with oocytes numbers collected from females at the same age at 5 pm (P = 0.0004 and <0.0001 respectively). Females at 4 and 5 weeks of age produced higher numbers of oocytes when superovulated at 7 pm. No statistical differences between females at different phases of the estrous cycle were found. These results showed that in C57BL/6J mice, hormones should be given at 3 or 7 pm for females at 3 weeks of age, however older females should be superovulated closer to the beginning of the dark cycle to reduce female mouse use and increase the numbers of oocytes produced per female.

The Proteome, Not the Transcriptome, Predicts that Oocyte Superovulation Affects Embryonic Phenotypes in Mice

“…If the above model is correct, then the logical follow-up experiment is to allow for more time until the release of the oocytes from the ovary, expecting to see a relief of the superovulation-associated deficits. Unlike the gonadotropin dosage 27,79,80 and the time of gonadotropin stimulation in relation to estrous cycle 81 and photoperiod 82 , the interval of the gonadotropins has not received much consideration, although it goes by itself that the accumulation of gene products in oocytes is a function of time during oogenesis. Compared to the natural length of the ovarian cycle in F1 mice, which is 4 days 83 , the interval eCG-hCG of the conventional superovulation spans only 2 days, thereby triggering the idea to assess the extent of preovulatory maturation attained until the administration of hCG.…”

Depletion of placental brain-derived neurotrophic factor (BDNF) is attributed to premature ovarian insufficiency (POI) in mice offspring

“…3G-H). One-month-old female mice are the best recipients for superovulation and harvesting eggs [37]. In one-month-old cKO(HE) mice, the number of eggs signi cantly decreased compared with the controls (Fig.…”

Fructose improves Titanium Dioxide Nanoparticles induced alterations in Developmental Competence of mouse oocytes

“…The mice were kept in temperature-controlled conditions under a 12 h light/dark cycle and allowed to freely access water and feed ad libitum in the Medical Experimental Research Center (MERC) of Mansoura University. To induce superovulation, each female mouse received intraperitoneal injection of 10 IU of pregnant mare serum gonadotropin (PMSG, Gonaser®, HIPRA, Spain) 48 h prior to scari cation of mice (53,54). This experiment was designed to assess the effect of i/p injection of TiO 2 NPs (100 mg/kg BW)…”