Effect of gonadotrophin dose on oocyte retrieval in superovulated BALB/c mice

Ovum pick-up and in vitro maturation in spotted paca (Cuniculus paca-Linnaeus, 1766)

We tested FSHp, eCG and FSHp + eCG to establish ovum pick-up (OPU) and in vitro maturation method in spotted paca. Eight healthy adult females were subjected to each of four treatments to stimulate ovarian follicular growth. All females were subjected to a hormonal protocol using a single dose of 45 mg of injectable progesterone and single intramuscular injection of 0.075 mg d-cloprostenol on day 6. Ovarian stimulation was carried out as follows: in Group TFE (FSHp and eCG), animals were treated with a single dose of 80 mg of FSHp and 200 IU of eCG intramuscularly on day 6 after the application of progesterone; in Group TF (FSHp), they were treated with a single dose of 80 mg of FSHp intramuscularly on day 6 after application of progesterone; in Group treatment eCG, they were treated with 200 IU of eCG intramuscularly on day 6 after application of progesterone; and in Group TC (saline solution), 1 ml of saline solution was administered to control does. The OPU was performed between 22 and 26 hr after gonadotropin treatments. All recovered oocytes were placed into maturation media and incubated for 24 hr. There were no differences among the mean number of observed follicles, aspirated follicles and oocytes recovered per treatment. Oocyte maturation rates did not differ among groups, except, TF and treatment eCG oocytes had greater maturation rates than TC oocytes. In this study, gonadotropin administration failed to superovulate treated does and increase oocyte retrieval efficiency. Despite the feasibility of the procedure, further studies are needed to develop and refine hormonal protocols for oocyte recovery and in vitro maturation in this species.

Comparative Analysis of Number and Competence in Meiotic Maturation of Preovulatory Oocytes of C57Bl/6J Mice and Their F1 Hybrids after Stimulation with Gonadotropin

The study examined maturation of preovulatory germinal vesicles oocytes (GV oocytes) induced by gonadotropic hormone PMSG in the inbred C57Bl/6J mice (viewed as a gold standard for diverse biomedical studies) as well as in the first generation hybrid C57Bl/6J×СВА/lac and СВА/lac×C57Bl/6J mice at various ages. The most effective donors of GV oocytes were СВА/lac×C57Bl/6J mice (F1 hybrids) yielding 25±2 oocyte/mouse. In contrast, a significantly smaller number of GV oocytes can be isolated from the ovaries of female C57Bl/6J or C57Bl/6J×СВА/lac mice under the same conditions. At this, the greatest number of GV oocytes (42±4) can be retrieved from the ovaries of immature hybrid СВА/lac×C57Bl/6J mice aged 4 weeks. These mice demonstrated the largest share of GV oocytes, which attained MII stage during in vitro culturing. The data conclude that F1 hybrid СВА/lac×C57Bl/6J mice can be viewed as a handy experimental source yielding a large number of GV oocytes capable of meiotic maturation in a culture.

Influence of polygamous versus monogamous mating on embryo production in four different strains of mice after superovulatory treatment

We determined the effect of monogamous or polygamous mating with 2 females on vaginal plug (VP) rate, embryo donors (ED), 2-cell embryo production, and male performance after superovulation of females aging 24d or 45-48d. C57BL/6NCrl (B6N), BALB/cAnCrl (BALB/cN), FVB/NCrl (FVB/N), and Crl:CD1(ICR) (CD-1) females received 5 IU eCG and 5 IU hCG (24d) or 7.5 IU eCG and 7.5 IU hCG (45-48d) 48 h apart. After the hCG injection, females were paired with males, which alternated weekly in monogamous or polygamous mating. Significant differences in the percentage of VP-positive females between monogamous and polygamous mating were observed for B6N (71% vs. 49%), FVB/N (77% vs. 51%), and CD-1 (90% vs. 67%) at 45-48d. BALB/cN and CD-1 showed higher VP rates than B6N and FVB/N. A significantly higher percentage of ED was found for monogamous than for polygamous mating for FVB/N (87% vs. 61%) at 24d and for B6N (91% vs. 53%) and CD-1 (90% vs. 68%) at 45-48d. In all strains of mice and in both age groups, no significant differences were observed in the number of intact 2-cells per VP-positive female, ED or treated female between monogamous and polygamous mating except in the B6N strain where monogamous mating resulted in a significantly higher number of intact 2-cell embryos per treated female than polygamous mating at both ages. The present results imply that polygamous mating can be implemented for 2-cell embryo production in all strains studied except for B6N when all females are euthanized. However, when only VP+ females are sacrificed polygamous mating can be employed for all 4 strains studied.

Administration of Gonadotropins for Superovulation in Mice

For experiments that require large numbers of preimplantation mouse embryos, such as microinjection of zygotes, gonadotropins are administered to females before mating to increase the number of oocytes that are ovulated (i.e., to induce superovulation). Pregnant mare serum gonadotropin (PMSG) is used to mimic the oocyte maturation effect of the endogenous follicle-stimulating hormone (FSH), and human chorionic gonadotropin (hCG) is used to mimic the ovulation induction effect of luteinizing hormone (LH).

Super pregnancy in a BALB/c mouse superovulated with PMSG

This paper reports a case of super pregnancy in a BALB/c mouse pregnant with 30 pups following induction of superovulation using a PMSG-hCG protocol. Superovulation was induced in 10 mice by injecting 5 IU PMSG followed by 5 IU hCG 48 hours later. Immediately after injection of hCG, animals were placed with males at a ratio of 1 to 1 for 24 hours. On day 14 after mating, animals were killed by cervical dislocation and the uterus was examined for pregnancy and the number of fetuses. The mean (±SEM) number of fetuses observed in ten mice was 5.4±3.18 with an unexpectedly super pregnant mouse bearing 30 fetuses on day 14 of pregnancy.

Impact of superovulation and mating on the wellbeing of juvenile and adult C57BL/6N mice

Superovulation of mice is routinely used to increase the number of obtainable ova per female. Because of the better outcome, prepubescent females are preferentially used. Here, we provide results of the impact of superovulation and mating on the wellbeing of juvenile compared with adult C57BL/6N mice. Two groups of mice (3–4 weeks vs 7–8 weeks old) were superovulated and mated. Observation of mating behaviour showed that reluctant adult females tended to fight the male’s approach, whereas juveniles preferred to take flight. Faeces were collected daily for the analysis of stress hormones. There was no difference in the levels of glucocorticoid metabolites either between age groups or between treated animals and their controls. Histology after mating revealed intact vaginal mucosa without any detectable lesions in all animals regardless of age. In contrast to adults, almost all juveniles were synchronised in oestrus and produced significantly more ova. Taken together, our results reveal no increased welfare problem from using juvenile mice for superovulation and mating. Considering the higher yield of fertilisable oocytes and zygotes, it is advisable to use C57BL/6N prepubescent mice in order to reduce the number of donor females required.

Superovulation, in vitro fertilization (IVF) and in vitro development (IVD) protocols for inbred BALB/cJ mice in comparison with outbred NMRI mice

Purpose

To study assisted reproductive technology (ART) protocols including superovulation, in vitro fertilization (IVF) and in vitro development (IVD) for BALB/cJ mice in comparison with a common ART protocol for NMRI mice.

Methods

Adult NMRI and BALB/cJ mice were superovulated using a 48 h G-interval. In order to find a more suitable G-interval for the BALB/cJ strain, G-intervals including 44, 46 and 50 h were also examined. Superovulation rates were recorded in all groups. IVF rate of BALB/c oocytes in T6 and mHTF media were compared. IVD rates of BALB/cJ zygotes in mHTF, T6 and G1V₅/G2V₅ media were compared. In addition, IVF and IVD rates of BALB/cJ and NMRI oocytes were compared in T6 medium during IVF-IVD procedures.

Results

In BALB/cJ mice the highest superovulation rates were observed with 44-46 h G-intervals. However, with a 48 h G-interval, superovulation rates were significantly lower in BALB/cJ compared to NMRI mice (p < 0.05). mHTF medium significantly increased in vitro fertilization of BALB/cJ oocytes compared to T6 medium (p < 0.05). Fertilization rate of NMRI oocytes was significantly higher than BALB/cJ oocytes in T6 medium (p < 0.05). The BALB/cJ embryo IVD was significantly higher in G1/G2 medium compared to mHTF and T6 media (p < 0.01).

Conclusions

Superovulation with 48 h G-interval and using T6 during all in vitro procedures produces embryos more efficiently for NMRI mice than for BALB/cJ mice. For BALB/cJ mice, a protocol including superovulation with a 44-46 h G-interval, using mHTF during IVF and G1V₅/G2V₅ medium during IVD, may improve in vitro embryo production.

Adaptation and reintegration of proprioceptive information in young and older adults' postural control

We investigated age-related changes in adaptation and sensory reintegration in postural control without vision. In two sessions, participants adapted their posture to sway reference and to reverse sway reference conditions, the former reducing (near eliminating) and the latter enhancing (near doubling) proprioceptive information for posture by means of support-surface rotations in proportion to body sway. Participants stood on a stable platform for 3 min (baseline) followed by 18 min of sway reference or reverse sway reference (adaptation) and finally again on a stable platform for 3 min (reintegration). Results showed that when inaccurate proprioception was introduced, anterior-posterior (AP) sway path length increased in comparable levels in the two age groups. During adaptation, young and older adults reduced postural sway at the same rate. On restoration of the stable platform in the reintegration phase, a sizeable aftereffect of increased AP path length was observed in both groups, which was greater in magnitude and duration for older adults. In line with linear feedback models of postural control, spectral analyses showed that this aftereffect differed between the two platform conditions. In the sway-referenced condition, a switch from low- to high-frequency COP sway marked the transition from reduced to normal proprioceptive information. The opposite switch was observed in the reverse sway referenced condition. Our findings illustrate age-related slowing in participants' postural control adjustments to sudden changes in environmental conditions. Over and above differences in postural control, our results implicate sensory reweighting as a specific mechanism highly sensitive to age-related decline.

Task prioritization in aging: effects of sensory information on concurrent posture and memory performance

In older adults, cognitive resources play a key role in maintaining postural stability. In the present study, we evaluated whether increasing postural instability using sway referencing induces changes in resource allocation in dual-task performance leading older adults to prioritize the more age-salient posture task over a cognitive task. Young and older adults participated in the study which comprised two sessions. In the first session, three posture tasks (stable, sway reference visual, sway reference somatosensory) and a working memory task (n-back) were examined. In the second session, single- and dual-task performance of posture and memory were assessed. Postural stability improved with session. Participants were more unstable in the sway reference conditions, and pronounced age differences were observed in the somatosensory sway reference condition. In dual-task performance on the stable surface, older adults showed an almost 40% increase in instability compared to single-task. However, in the sway reference somatosensory condition, stability was the same in single- and dual-task performance, whereas pronounced (15%) costs emerged for cognition. These results show that during dual-tasking while standing on a stable surface, older adults have the flexibility to allow an increase in instability to accommodate cognitive task performance. However, when instability increases by means of compromising somatosensory information, levels of postural control are kept similar in single- and dual-task, by utilizing resources otherwise allocated to the cognitive task. This evidence emphasizes the flexible nature of resource allocation, developed over the life-span to compensate for age-related decline in sensorimotor and cognitive processing.

Mouse major urinary proteins trigger ovulation via the vomeronasal organ

The major urinary proteins are a species-specific complex of proteins excreted by male mice that influence the reproductive behavior and the neuroendocrine condition of female mice through the olfactory system. The aim of this work is to determine their influence on ovulation. The major urinary proteins isolated from the urine of adult male mice were voided of bound odorants, dissolved at a physiological concentration in urine of prepubertal mice, and put on the nostril of reproductively cycling female mice housed in groups, the first day of estrus at 1100. The eggs shed in the oviducts were counted under dissection the morning of the second day of estrus. The results showed that 1) a single stimulus of the major urinary proteins increased ovulation nearly as much as the whole urine of male mice, 2) the effect was not elicited by male rat urine which contains different proteins, 3) a peptide with four residues of the amino-terminal sequence of the major urinary proteins stimulated ovulation, and 4) mice that had been isolated or had the vomeronasal organ (VNO) removed did not respond to the major urinary proteins and had a high spontaneous ovulation. The results suggest that the major urinary proteins activate the neuroendocrine system through the VNO and trigger ovulation.

Effect of Concomitant Use of Benzodiazepines and Other Drugs on the Risk of Injury in a Veterans Population

BACKGROUND

Benzodiazepines comprise a class of drugs that when used as monotherapy are generally acknowledged to pose a risk for injury by increasing the likelihood of falls, fall-related injuries, adverse drug events and car accidents. Benzodiazepines may also be used concomitantly with other high risk medications that may further exacerbate the risk of injury. The aim of this study is to examine the occurrence of the concomitant use of benzodiazepines and other drugs and then quantify the indirect effect of these drug combinations on the likelihood of an injury-related health care episode.

METHODS

A multivariate model was specified that included outpatient prescription data and inpatient/outpatient medical utilisation records for 13,745 patients at a Veterans Administration hospital system over a 3-year period (1999-2001). We analysed 1,33,872 outpatient benzodiazepine prescriptions and >1.5 million non-benzodiazepine prescriptions for the study population. Micromedex software was used to identify combinations of benzodiazepines and other drugs that are likely to result in 'major' interactions. We then further restricted our focus to the use of these drug combinations within a 30-day period prior to an injury-related medical event. The adjusted odds ratio on a variable characterising concomitant use of a benzodiazepine and another drug within this period was used to quantify the relative risk of injury. The principal outcome was the estimated risk of an injury-related health care episode within a 30-day period when taking both a benzodiazepine and another drug with a 'major' severity rating as defined by Micromedex. The risk of injury was adjusted for comorbidities, hospital discharges, marital status, age, mean arterial pressure and body mass index, as well as the dose of benzodiazepine (converted to diazepam equivalents) and duration of benzodiazepine treatment.

RESULTS

Of the 1,110 unique individuals who experienced an injury, 790 (71.2%) patients had used a benzodiazepine in combination with another drug. Furthermore, only 4.3% (320/7522) of the patients taking benzodiazepines who did not have concomitant drug use experienced an injury. The occurrence of this concomitant use increased the odds of an injury >2-fold in the model. Dose and duration of benzodiazepine use, as well as certain comorbidities, were also associated with an increased risk for injury, whereas being married reduced the risk.

CONCLUSIONS

This is the first large-scale study to quantify the impact of concomitant use of benzodiazepines and other drugs on the risk of injury in a population of Veterans Administration patients. It demonstrates the utility of expanding the focus of inappropriate medication usage to include analyses that link potentially inappropriate drug use with health care utilisation for injuries.

Administration of increasing amounts of gonadotrophin compromises preimplantation development of parthenogenetic mouse embryos

The aim of the present study was to examine the effect of ovarian stimulation with increasing amounts of pregnant mare's serum gonadotrophin (PMSG) on preimplantation development of diploid parthenogenetic embryos in vitro. Administration of 5, 10 and 20 IU PMSG significantly increased the number of oocytes obtained per mouse in a dose-dependent manner. The amount of PMSG administered did not alter the proportion of degenerate oocytes. However, there was a significant decrease in the proportion of 8-cell/compacted embryos after 53 h of culture with the administration of increasing amounts of PMSG. Proportion of embryos reaching at the blastocyst stage after 79 h of culture was reduced significantly in both the 10 and 20 IU PMSG groups. Reduced blastocyst development after 96 h of culture, however, was significant only in the 20 IU PMSG group. Total blastocyst, trophectoderm and inner cell mass numbers were also reduced significantly with the administration of 20 IU PMSG. It is concluded on the basis of these observations that preimplantation development of diploid parthenogenetic oocytes, which depends virtually entirely on maternal molecules accumulated during oogenesis along with gene products derived from the maternal genome, is compromised with the administration of increasing amounts of PMSG.

Comparison between PMSG- and FSH-induced superovulation for the generation of transgenic rats

Superovulation protocols using single injections of pregnant mare's serum gonadotropin (PMSG) or minipumps with follicle-stimulating hormone (FSH) were compared in immature Sprague-Dawley (SD) rats. We used the following criteria: total number of ova, rate of fertilization, in vitro embryo development, sensitivity of zygotes to the microinjection of foreign DNA into the pronucleus, and their in-vivo development after transplantation into the oviduct of a recipient. Female SD rats were stimulated with 15 IU PMSG or 10 mg FSH followed by the injection of human chorionic gonadotropin (hCG) at doses of 20 and 30 IU per female. After hCG administration, they were mated with males of the same strain and sacrificed on day 1 of pregnancy. The percentage of mated animals and the fertilization rate was similar in all groups. In rats given PMSG, the number of ovulated zygotes was hCG dose-dependent. In contrast, the dose of hCG did not influence the efficiency of superovulation in rats given FSH, which was equal to PMSG-treated rats at the optimal dose of hCG. The rates of in vitro blastocyst development (31.4 and 23.3%) and the resistance to microinjection into the pronucleus did also not differ significantly between zygotes of both studied groups. The proportion of offspring developing from microinjected zygotes after oviduct transfer (26.2 and 26.8%, respectively) and the rate of transgene integration per newborns (7.3 and 4.9%, respectively) was similar in both experimental groups. The results of this study demonstrate that superovulation of immature SD rats by PMSG is equally effective as FSH treatment and, thus, preferable for transgenic rat technology due to the lower costs and easier handling.