Survival Rate Of Pups Research Articles

Effect of Lactational Low-Protein Diet on Skeletal Muscle during Adulthood and Ageing in Male and Female Mouse Offspring.

Sarcopenia is characterised by the loss of skeletal muscle mass and function, which leads to a high risk of increased morbidity and mortality. Maternal malnutrition has been linked to impaired development of skeletal muscle of the offspring; however, there are limited studies that report the long-term effect of a maternal low-protein diet during lactation on the ageing of skeletal muscles. This study aimed to examine how a maternal low-protein diet (LPD) during lactation affects skeletal muscle ageing in the offspring. Pups born from control mothers were lactated by mothers fed with an LPD. Post-weaning, mice were either maintained on an LPD or switched to a control, normal-protein diet (NPD). In males, an LPD mainly affected the size of the myofibres without a major effect on fibre number and led to reduced grip strength in ageing mice (24 months). Female mice from mothers on an LPD had a lower body and muscle weight at weaning but caught up with control mice at 3 months. During ageing, the muscle weight, myofibre number and survival rate of female pups were significantly affected. These findings highlight the effect of an LPD during lactation on skeletal muscle ageing, the lifespan of offspring and the importance of sexual dimorphism in response to dietary challenges.

General toxicity and screening of reproductive and developmental toxicity following bioaccumulation of oral-dosed perfluorooctanoic acid: Loss of the Golgi apparatus

Despite its widespread use as a stabilizer across various industries over the past several decades, the health effects of chronic exposure to PFOA are still unclear. We administered PFOA by oral gavage (0, 12.5, 50, and 200 μg/day/mouse, eight groups) to male and female mice for six months. Body weight gain decreased with dose accompanied by increased liver weight, and PFOA altered liver damage-related-blood biochemical indicators and induced pathological lesions, including hepatocellular hypertrophy, cholangiofibrosis, and centrilobular hepatocellular vacuolation. Loss of the Golgi apparatus, formation of lamellar body-like structures, and lipid accumulation were observed in the liver of PFOA-treated mice. We also cohabited five pairs of male and female mice for the last ten days of administration, dosed PFOA to dam up to 28 days after birth, and investigated effects on reproduction and development. The survival rate of pups and the sex ratio of surviving mice decreased significantly at the highest dose. PFOA tissue concentration increased with the dose in the parent mice's liver and the pups' blood and brain. Taken together, we suggest that PFOA primarily affects the liver and reproduction system and that disturbance in lipid metabolism and Golgi's structural stability may be involved in PFOA-induced toxicity.

Effect of Parental Age, Parity, and Pairing Approach on Reproduction in Strain 13/N Guinea Pigs (Cavia porcellus)

Guinea pigs are important animal models for human disease, and both outbred and inbred lines are utilized in biomedical research. The optimal maintenance of guinea pig colonies, commercially and in research settings, relies on robust informed breeding programs, however, breeding data on specialized inbred strains are limited. Here, we investigated the effects of parental age, parity, and pairing approaches on mean total fetus count, percentage of female pups in the litter, and pup survival rate after 10 days in strain 13/N guinea pigs. Our analysis of colony breeding data indicates that the average litter size is 3.3 pups, with a 25.2% stillbirth rate, a failure-to-thrive outcome in 5.1% of pups, and a 10 day survival rate of 69.7%. The only variable to significantly affect the reproductive outcomes examined was parental age (p < 0.05). In comparison to adults, both juvenile and geriatric sows had lower total fetus counts; juvenile boars had a higher percentage of females in litters, and geriatric boars had a lower 10 day survival rate of pups. These studies provide valuable information regarding the reproductive characteristics of strain 13/N guinea pigs, and support a variety of breeding approaches without significant effects on breeding success.

Optimization of Milk Substitutes for the Artificial Rearing of Chinese Tree Shrews (Tupaia belangeri chinensis).

Simple SummaryThe Chinese tree shrew, a squirrel-like mammal, has been widely used as a laboratory animal in biological research. However, the low survival rate of the pups has seriously hindered the establishment of inbred lines of this species and further limited its wider use. We found a milk substitute appropriate for artificial rearing of Chinese tree shrew pups independent of any obvious adverse effects on their survival, health, and reproductive performance compared to those of the maternally reared pups. The successful optimization of a milk substitute for the artificial rearing of Chinese tree shrew pups may increase the availability of this experimental animal.The Chinese tree shrew (Tupaia belangeri chinensis) has the potential to replace the use of non-human primates in biomedical research. To increase the availability of this species, we have undertaken the ambitious task of establishing inbred lines of the Chinese tree shrew; however, we have been hindered by a low survival rate of inbred pups. Here, we report our artificial rearing (AR) of Chinese tree shrew pups using four different milk substitutes: the formula described by Tsang and Collins (milk TC) and three commercially available milk substitutes intended for possums (milk A and milk C) and for guinea pigs (milk B). We compared the effects of these milk substitutes and maternal milk on the daily milk consumption, growth performance, and survival of the pups. We also assessed the life span and reproductive performance of the F1 individuals given the best milk substitute as compared to the maternally reared (MR) pups. Milk B was found to be appropriate for AR. Pups fed with milk B had a high survival rate at the weaning age compared to those fed with the other milk substitutes. The AR pups fed with milk B had a life span similar to that of MR pups. AR females fed with milk B had an earlier age of the first reproduction, a larger number of litters, and a higher rate of survival of the offspring at the weaning age compared with the MR females. The successful optimization of a milk substitute for AR of Chinese tree shrew pups will undoubtedly facilitate the wide usage of this experimental animal.

Lactogenic effect of Polyscias scutellaria extract to maintain postpartum prolactin and oxytocin in lactating rats

BackgroundHypogalactia remains a challenge for mother to complete exclusive breastfeeding. Shield aralia (Polysicias scutellaria) has been used by Indonesian society to increase breast milk production. ObjectiveThis study aimed to elucidate the novel galactopoietic effect of P. scutellaria extract (PSE) in lactating rats for three weeks. Materials and methodsPSE were assayed for total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity. The secondary metabolites of PSE were determined by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). After parturition, dams were randomly divided into four groups: lactating rats (LR) + distilled water (LRO), LR + Asifit, and LR + PSE at doses of 250 and 500 mg/kg body weight (BW). Virgin rats served as the control group. The treatments were given for 14 days. ResultsThere were no significant differences (p > 0.05) in TPC, TFC, and antioxidant capacity among the three solvents. LC-HRMS revealed 22 compounds greater than 70 of the best-match, which were categorised as flavonoids, terpenoids, phenolic acids, and lignan. PSE increased the weight gain and survival rate of pups from our 3-week observation. Serum Prl was significantly higher (p < 0.05) in lactating rats treated with PSE 250 mg/kg BW at the first and third weeks than in the LRO group. Oxt serum was significantly higher (p < 0.05) in lactating rats treated with PSE (500 mg/kg BW) in the first and second weeks than in the LRO group. ConclusionPSE-rich polyphenols are promising galactopoietics by orchestrating Prl and Oxt and reducing the mortality of pups.

Mouse Modeling of Small for Gestational Age with Obese Metabolic Phenotypes in Adult Stage

Background Small for gestational age (SGA) in human is defined as the newborns with birth weight below the 10th percentile, whose prevalence continues to increase due to advanced maternal age. SGA children have a higher risk of developing metabolic disorders including obesity and diabetes later in adult life. Reliable SGA mouse models are needed to study their pathophysiology. Previous reports have suggested various SGA mouse models through dietary restriction of pregnant dams, but their low reproducibility is no small limitation. Therefore, we attempted to improve SGA mouse models with high reproducibility by modifying the dietary restriction. We aimed to model SGA with a smaller height and weight at birth followed by phenotypes of metabolic disorders including glucose tolerance and fatness in adult stages. Methods The 8-week-old C57BL6/J mice were given a normal Chow diet and protein-restricted diet (PRD, 6% protein by kcal) during pregnancy or pregnancy plus lactation. In the PRD group, frequent cannibalism and neglect occurred, so the foster mother system was introduced to minimize the mortality rate. Body weight and nasal-anal length were measured to define SGA. Intraperitoneal glucose tolerance test and body composition (fatness) were measured as metabolic variables. Results By PRD during pregnancy (~3 week), significantly smaller height (30.1±0.2 vs 22.4±0.4 mm, p<0.0001) and weight [1.42±0.02 vs 0.83±0.02 g, p<0.0001 (n=19~37)] and weight at birth were achieved. However, the survival rate in PRD group after postnatal day (PND) 1 was very low (38.1%) due to cannibalism and neglect from dams. We supposed that a golden time exists to rescue newborns to the foster mother to increase the survival, and the survival rate of PND 1 was increased up to 70% by rigorous care before 9am on e19.5 day (plus 1pm and 5pm if needed): fast delivery to the foster mother immediately after birth was most important for the survival. Most PRD group caught up with the height and weight of control group in the first week (PND 7), and there was no difference in body fat mass or glucose tolerance tests in 32 weeks of age. To induce metabolic phenotypes and failure of catch-up growth, PRD period was extended from pregnancy to even lactation period (~6 week). With this extended protocol, the differences in height were maintained until 12 weeks of age and there was a significant difference in body mass index (BMI) [male 0.30±0.01 vs 0.36±0.01 g/cm2, p<0.0001 (n=6~10); female 0.25±0.01 vs 0.31±0.01 g/cm2, p<0.0001 (n=7 for each)] in 12 weeks of age. Conclusion Sufficient duration of protein restriction (pregnancy ~ lactation) yields better phenotype of SGA with high adult BMI with improved survival rate of SGA pups by the rigorous care. Various metabolic parameters are regularly being measured further to confirm metabolic derangement, and if appropriate, this method can be effectively used in future studies.

Mating System, Breeding Success, and Pup Mortality of a Habitat Specialist Rodent: A Field and Molecular-based Approach

Mating systems are studied due to their interest in ecology and evolution. In rodents, mating strategies have been inferred from the spatio-temporal arrangement of males and females, and breeding success has usually been estimated through the number of embryos counted by palpation of pregnant females. However, these might not be trustable proxies to describe the mating systems and to estimate survival rate of pups. In this study, we surveyed breeding and reproduction of the southern water vole (SWV) (Arvicola sapidus) in six ponds over a three-year period. We combined capture-mark-recapture data with parentage analyses based on 444 individual genotypes with seven microsatellites: i) to estimate reproductive rate, ii) to compare field-based and molecular estimates of the mortality rate of juveniles and the effective breeding success of adults, iii) to find individual traits or environmental conditions related to breeding success, and iv) to describe the mating system of SWV. Our results suggest that mortality rate during the pre- and post-weaning period is around 63% and 27%, respectively, and reinforce our hypothesis that the high reproductive rates in SWV compensate for the high mortality of juveniles. Parentage analyses assigned one or two parents to 80% of the target juveniles and suggest promiscuity as the mating system of SWV, probably as a strategy to minimize infanticide by males, although deviations from promiscuity might arise depending on variations of ecological factors. Weight is positively correlated with reproduction rate, as heavier (dominant) females allocate nests in better habitat patches (minimizing nest predation) and heavier (dominant) males expand their home ranges so they can have access to more mates.

Research on the Application of Artificial Intelligence Technology in Animal Embryo Transfer

Animal embryo transfer technology can show strong practical value, and its use in the animal husbandry industry is particularly prominent. It should be because this technology can significantly increase the birth rate and survival rate of animal pups within a period of time. This technology can also the animal’s own reproductive ability has been further improved. With the popularization of this animal embryo transfer technology, the animal husbandry industry can achieve rapid development in a short period of time, enabling farmers to obtain higher and better economic benefits. Since animal embryo transfer technology entered the field of animal husbandry in the 1970s, the role of animal embryo transfer technology has become increasingly apparent. This technology has penetrated into biological reproduction technologies such as animal breeding, gender control and animal cloning. And animal reproduction technology has become leading the cutting-edge scientific reproduction technology of the livestock industry in the 21st century. Nowadays, artificial intelligence technology combines the research results of many disciplines such as theoretical science, technical science, and applied science. As a practical technology leading a new generation of technological revolution and industrial reform, artificial intelligence technology has a significant impact on human social progress, economic development, and biotechnology. However, the transformation of artificial intelligence technology has also brought some huge challenges to social stability. How to treat artificial intelligence and animal embryo transfer technology, how to integrate and coordinate these two technologies, and how to solve these technical design problems have become the urgent problems that need to be solved.

Low pup survival rate is associated with maternal Naq3 genotype and hypothalamic Vps8 expression levels in mice.

Pups born from females of the inbred mouse strain RR/Sgn tend to have low survival rates during rearing. We have previously identified Naq3, a quantitative trait locus underlying this low pup survival rate. In the present study, we confirmed the effect of Naq3 in congenic mice and investigated whether Vps8 is a candidate gene for Naq3. The survival rate of pups on the twelfth postpartum day was significantly decreased for mothers homozygous for the Naq3 allele. Hypothalamic expression of Vps8 was induced by nurturing in wild-type mice, and was significantly lower in Naq3 congenic mice than in wild-type mice. Thus, Vps8 is suggested to be involved in maternal nurturing, and therefore, as a plausible candidate gene for Naq3.

Эмбриотоксические свойства лекарственного средства на основе комплекса лития цитрата, полиметилсилоксана и оксида алюминия в эксперименте

Проведено исследование эмбриотоксического действия нормотимического лекарственного средства на основе комплекса лития цитрата, полиметилсилоксана, оксида алюминия (далее — комплекс лития) в антенатальном и постнатальном периодах развития. Установлено, что в результате применения комплекса лития в дозах 400 и 2000 мг/кг 1 раз в день внутрижелудочно с 1-го по 19-й и с 6-го по 20-й день беременности у крыс выявляется ряд эмбриотоксических эффектов, зависящих от дозы препарата и проявляющихся как в антенатальном, так и постнатальном периоде. В антенатальном периоде развития потомства животных, получавших комплекс лития в течение всего периода беременности, выявлено повышение частоты гибели эмбрионов и плодов до имплантации на (17,5 ± 3,1) % (доза 2000 мг/кг), а после имплантации — на (26,6 ± 5,2) % (доза 2000 мг/кг) и на (15 ± 2,3) % (доза 400 мг/кг), увеличение числа плодов с кровоизлияниями в коже на 12,4 % (доза 2000 мг/кг) и патологическими изменениями внутренних органов в среднем на 50 % (доза 2000 мг/кг) и на 30,7 % (доза 400 мг/кг). В постнатальном периоде развития потомства животных, получавших комплекс лития на 6 – 20-й дни беременности в дозе 2000 мг/кг, выявлено снижение индекса выживаемости крысят на 57,7 %, замедление у них скорости физического развития на 32,4 % и формирования сенсорно-двигательных рефлексов на 21,7 %, снижение способности к обучению и адаптивному поведению на 46,9 % (p &lt; 0,05) Таким образом, препарат обладает дозозависимой эмбриотоксичностью средней степени выраженности, проявляющейся в анте- и постнатальном периоде развития потомства.

Quercetin Prevents Lipopolysaccharide-Induced Experimental Preterm Labor in Mice and Increases Offspring Survival Rate.

Premature labor is still a worldwide problem, causing serious social economic burden and family burden. Currently, there is no effective way to prevent preterm labor. Since inflammation increases the risk of preterm birth and quercetin is reported to have anti-inflammation, immune-enhancement, and antioxidative effects, this study aims to explore whether quercetin exerts inhibitory effect on preterm labor in mice and increases offspring survival. Lipopolysaccharide (LPS) is one of the commonly used drugs in the inflammatory animal model of preterm birth. On day 15 of pregnancy, mice received a dose of vehicle phosphate-buffered saline (PBS) or a dose of quercetin (low concentration, 30mg/kg; medium concentration, 90mg/kg; high concentrations, 150mg/kg) via oral gavage. After 2h, mice received a dose of LPS (50μg/kg) or vehicle intraperitoneally (i.p.). In the absence of quercetin, a 100% incidence of preterm labor was observed in LPS-treated mice, and the fetuses were all died. Medium concentration of quercetin significantly prevented 63.5% of LPS-induced inflammatory preterm labor, and the survival rate of pups on day 22 was 83.76%. Specifically, quercetin significantly inhibited LPS-induced upregulation of NF-kappa-B/P65(RELA), AP-1/C-JUN(JUN), cyclooxygenase-2(PTGS2), and interleukin 6(IL6) in mice myometrium on mRNA level and inhibited the upregulation of P65 and C-JUN on protein level. Based on these observations, we concluded that quercetin exerts inhibitory effect on LPS-induced experimental mice preterm labor and increases offspring survival through a mechanism involving NF-κB/AP-1 pathway.

Postnatal Development of Speckled Ground Squirrel (Spermo-philus suslicus Guld, 1770) (Sciuridae, Mammalia) in Captivity

Журнал принимает на русском и английском языках статьи, представляющие результаты научных исследований в различных областях теоретической и прикладной экологии. Приоритет отдается научным статьям, основанным на явно сформулированных гипотезах.

Ameliorative effects of pre-eclampsia by quercetin supplement to aspirin in a rat model induced by L-NAME

As an inflammatory disease, pre-eclampsia is correlated with elevation of pro-inflammatory cytokines and maternal endothelial dysfunction. Aspirin plays an important role in the prevention and therapy of pre-eclampsia. Quercetin is a bioflavonoid which has anti-oxidant and reno-protective abilities. We aimed to figure out the effects of quercetin supplement to aspirin on the therapy against pre-eclampsia. Female pregnant Sprague-Dawley rats were divided into five groups according to the drug treatment. Aspirin [1.5 mg/kg body weight (BW)] or quercetin (2 mg/kg BW) treatment was administered from gestational day (GD) 4 to GD19. Rat model of pre-eclampsia was induced by NG-nitro-Larginine-methyl-ester (L-NAME). In pre-eclampsia rats induced by L-NAME, systolic blood pressures (SBP), proteinuria, malonyldialdehyde (MDA), and inflammatory cytokines levels were decreased by the treatment of quercetin supplement to aspirin. In the uterus, quercetin supplement to aspirin prevented the expression of VEGF and sFlt-1 mRNA. The treatment of quercetin supplement to aspirin rescued the declined survival rate and weight of pups caused by L-NAME-induced pre-eclampsia. Based on our study, compared with the treatment of aspirin alone, quercetin supplement to aspirin enhanced the therapeutic effects of aspirin on pre-eclampsia rats induced by L-NAME.

Novel Murine Model of Immune Thrombocytopaenia through Immunized CD41 Knockout Mice.

Immune thrombocytopaenia (ITP) is the most common autoimmune bleeding disorder, where platelets are destroyed by auto-antibodies and/or cell-mediated mechanisms. To understand the pathogenesis of ITP and explore novel therapeutics, three types of animal models have been used: passive ITP, secondary ITP and platelet-induced ITP. However, the first two are not ideal for chronic ITP pathophysiology where both T cell and B cell play important roles in platelet destruction. The most efficient model to mimic chronic ITP is developed by Chow et al through transferring splenocytes from platelet-immune CD61-knockout (KO) mice into mice with severe combined immunodeficiency (SCID). However, placental defects are evident in 25% of CD61-KO females and post-natal haemorrhage does occur, reducing the survival rate of embryos and pups. Compared with CD61-KO mice, CD41-KO ones do not present such problems. In our study, we employ CD41-KO mice as another source of immunized spleen cells. We evaluated our model with existing standards. Transferred SCID mice presented typical features of ITP, such as reduced platelet counts in the peripheral blood, increased anti-platelet antibody levels in the serum and reduced mature megakaryocytes in the bone marrow. What is more, lymphocyte-depletion experiments showed the role of CD8+ T cells in mature megakaryocyte decrease and thrombocytopaenia. And we confirmed the antibody-mediated platelet destruction by phagocytosis in the spleen. Our study develops another efficient murine ITP model through immunized CD41-KO mice.

Immunization with Toxoplasma gondii GRA17 Deletion Mutant Induces Partial Protection and Survival in Challenged Mice.

Toxoplasmosis remains a world-threatening disease largely because of the lack of a fully effective vaccine. Here, we created a ΔGRA17 mutant by disrupting the virulence factor GRA17 using CRISPR-Cas9 method. Then, we tested whether ΔGRA17 tachyzoites can be used as a live-attenuated vaccine against acute, chronic, and congenital Toxoplasma gondii infection in mice. Immune response evoked by ΔGRA17 immunization suggested a sequential Th1 and Th2 T cell response, indicated by high levels of Th1 and a mixed Th1/Th2 cytokines at 28 and 70 days after immunization, respectively. ΔGRA17-mediated immunity fully protected mice against lethal infection with wild-type (wt) RH strain, heterologous challenge with PYS, and TgC7 strains of the Chinese ToxoDB#9 genotype, and T. gondii Pru strain. Although parasite cysts were detected in 8 out of 10 immunized mice, cyst burden in the brain was significantly reduced (P < 0.05) in immunized mice (53 ± 15 cysts/brain) compared to non-immunized mice (4,296 ± 687 cysts/brain). In respect to congenital infection, the litter size, survival rate, and body weight (BW) of pups born to ΔGRA17-immunized dams were not different compared to pups born to naïve control dams (P = 0.24). However, a marked reduction in the litter size (P < 0.001), survival rate, and BW (P < 0.01) of pups born to non-immunized and infected dams was detected. Also, immunized dams infected with type II Pru strain had significantly (P < 0.001) less cyst burden in the brain compared with non-immunized and infected dams. These findings show that immunization with ΔGRA17 strain evokes cell-mediated and neutralizing antibody responses and confers some degree of protection against challenge with homologous and heterologous virulent T. gondii strains.

Effects of prenatal maternal seizure on hippocampal damage and cognitive deficits in offspring rats

Objective: To observe hippocampal damage and cognitive impairment of offspring exposed to prenatal maternal seizure induced by amygdala kindling, and to explore the underlying mechanism by the detection of pathological changes of placenta. Method: Adult female SD rats were randomly divided into three groups: control group(8 rats), kindling group(12 rats) and sham group(8 rats). All the rats were allowed to mate after one week's fully kindling. The pregnant rats in kindling group received electric stimulation every 48 h. Dams were allowed to deliver naturally. Effects of maternal seizure on the number of offspring, the survival rate and body weight of pups were observed. HE staining was used to visualize histopathological changes of placenta. Morris water maze test was used to assess the cognitive function and Nissal's staining to detect hippocampal morphology of the offspring. One-way ANOVA analysis and χ2 test were used. Result: Compared with the sham group (95%(78/82)) and the control group (95%(82/86)), the survival rate of pups in kindling group(81%(66/82))was much lower (χ2=13.817, P=0.001). There were no significant differences in the number of pups per litter and pups birth-weight between kindling group and sham group or control group(F=0.312 and 0.257, P=0.736 and 0.776). HE staining showed that placental tissues from control and sham groups were normal whereas the histologic abnormalities of placentas from kindling group were characterized by thickening of the villus vascular walls, luminal stenosis, trophoblasts hyperplasia, abnormalities of trophoblasts with nuclear pyknosis and karyorrhexis and accumulation of inflammatory lymphocytes in labyrinthine zone. Nissl staining showed that neurons in hippocampus of P0(0 d after birth) and P84(84 d after birth) offspring from control and sham groups were normal, but neuronal damages were obvious in hippocampus of P0 and P84 offspring from kindling groups, and the damages in P0 pups were severe with a marked loss of neuron, shrinkage of cells and nuclear pyknosis and karyorrhexis. In the Morris water maze, compared with the sham group ((29±8), (19±9), (10±4)s) and the control group ((25±6), (17±5), (14±4)s) rats in the kindling group ((36±8), (29±8), (30±11)s) exhibited significantly longer escape latency from the 3rd, 4th, and 5th days (F=6.276, 7.518, 18.422, P=0.030, 0.003, 0.000), significant less time in the target quadrant ((27±8) vs.(58±11)and(68±13)s, F=35.993, P=0.000) and reduced number of crossing the platform ((4.4±1.7) vs. (7.2±1.6) and (8.5±1.3)times, F=18.377, P=0.000). In addition, there was no significant difference between control and sham groups(P all >0.05). Conclusion: The prenatal maternal seizures induced significant pathological damages to hippocampus and cognitive impairment of offspring. Hypoxia-ischemia of placenta might play an important role in this process.

Effects of mifepristone and quinestrol on the fertility of female Brandt’s voles (Lasiopodomys brandtii) in different reproductive phases

Mifepristone and quinestrol are effective drugs for controlling rodent fertility, but their inhibitory effectiveness during premating, early pregnancy, and late pregnancy is unknown. In this study, six groups of eight female Brandt’s voles (Lasiopodomys brandtii) were administered with mifepristone, quinestrol, or a control for three days during premating, early pregnancy, or late pregnancy. In the mifepristone-treated groups, the premating females bred, whereas the early and late pregnant females did not. The reproductive rate, litter size, average body mass at birth, and survival rate of pups did not significantly differ between the mifepristone-treated premating group and the control group. By contrast, quinestrol treatment completely inhibited fertility during the three reproductive phases. In addition, fertility was not completely restored in the second pairing. The reproductive rates were higher for mifepristone, both during early and late pregnancy, than for quinestrol, but both were lower than the control. Thus, mifepristone and quinestrol both inhibited the fertility of female Brandt’s voles at different reproductive periods. These results suggest that these two sterilants could be delivered during the reproductive season of the target pest animal.

Genetic analysis of low survival rate of pups in RR/Sgn inbred mice.

Newborn offspring of the inbred mouse RR/Sgn strain have a low survival rate prior to weaning. We hypothesized that this is a consequence of an inferior nurturing ability of RR/Sgn mothers and that RR/Sgn mothers have a tendency to lose their pups. We performed quantitative trait locus (QTL) mapping for inferior nurturing ability and tendency to lose pups in RR/Sgn mothers. The number of pups was adjusted to 6 per dam on the day of delivery, and the number of surviving pups and their total weight (litter weight) were scored at 12 days after birth. Nurturing ability was evaluated by litter weight, and tendency to lose pups was evaluated by scoring whether or not the mothers lost their pups. For litter weight, we identified one significant QTL on chromosome 4 and three suggestive QTLs on chromosomes 7, 9 and 17. The RR/Sgn allele was associated with lower litter weight at all loci. For the tendency to lose pups, we identified three suggestive QTLs on chromosomes 4, 9 and 16. The RR/Sgn allele was associated with an increased tendency to lose pups at all loci. These results supported our hypothesis that the low survival rate phenotype was attributable, at least in part, to a phenotype whereby mothers display inferior nurturing ability and a tendency to lose pups. Thus, it suggests that these two traits share genetic basis.

Neonatal Exposure to Sevoflurane in Mice Causes Deficits in Maternal Behavior Later in Adulthood

In animal models, exposure to general anesthetics induces widespread increases in neuronal apoptosis in the developing brain. Subsequently, abnormalities in brain functioning are found in adulthood, long after the anesthetic exposure. These abnormalities include not only reduced learning abilities but also impaired social behaviors, suggesting pervasive deficits in brain functioning. But the underlying features of these deficits are still largely unknown. Six-day-old C57BL/6 female mice were exposed to 3% sevoflurane for 6 h with or without hydrogen (1.3%) as part of the carrier gas mixture. At 7-9 weeks of age, they were mated with healthy males. The first day after parturition, the maternal behaviors of dams were evaluated. The survival rate of newborn pups was recorded for 6 days after birth. Female mice that received neonatal exposure to sevoflurane could mate normally and deliver healthy pups similar to controls. But these dams often left the pups scattered in the cage and nurtured them very little, so that about half of the pups died within a couple of days. Yet, these dams did not show any deficits in olfactory or exploratory behaviors. Notably, pups born to sevoflurane-treated dams were successfully fostered when nursed by control dams. Mice coadministered of hydrogen gas with sevoflurane did not exhibit the deficits of maternal behaviors. In an animal model, sevoflurane exposure in the developing brain caused serious impairment of maternal behaviors when fostering their pups, suggesting pervasive impairment of brain functions including innate behavior essential to species survival.

Effects of cabergoline on the fertility of female mice during early and late pregnancy, and potential for its use in mouse control

To evaluate the dose effects of cabergoline on the fertility of female mice during early or late pregnancy, cabergoline was continuously administered by gastrogavage for three days within 1 day to 3 day or 15 day to 17 day of gestation. The body mass, reproductive rate, litter size at birth and weaning of females, as well as the body mass, survival rate of pups, were recorded. During early pregnancy, cabergoline treatment effectively terminated the pregnancy of mice. Cabergoline (100μg/kg) was half effective in terminating pregnancy and significantly reduced the average litter size and survival rate of pups compared with those of the controls. Cabergoline treatment of 200 and 400μg/kg completely terminated pregnancy of mice and induced incomplete restoration of fertility (40% and 44%, respectively) even at the second cycle of reproduction. During late pregnancy, cabergoline did not change the litter size at birth but significantly reduced the litter size at weaning and the survival rate of pups, 400μg/kg cabergoline markedly reduced the survival rate to 77% compared with the controls. The death of pups mainly occurred during seven days after parturition. Cabergoline had no significant difference on the average body mass of surviving pups in treated groups compared with controls during lactation. In conclusion, cabergoline may inhibit or reduce the reproduction of female mice, and demonstrate different dose effects on the fertility during early or late pregnancy. Together with infertility efficacy in phase prior to mating and lactation, cabergoline is a potential fertility control agent for pest rodent control.