RESUMEN
BACKGROUND: Most human demographic data, particularly those on natural fertility populations, find no relationship or even a positive association between fertility and longevity. The present study aims to ascertain whether there is a trade-off between fertility and longevity in the mouse model. METHODS: The study was focused on the first litter produced by 10- to 14-wk-old hybrid (C57BL/6JIco female X CBA/JIco male) mice. A single female/male per litter was individually housed with a male/female at the age of 25 and 52 wk, respectively, until the end of reproductive life in females or natural death in males under controlled housing conditions. Post-reproductive females and virgin mice were reared until natural death. Cox regression models with forward stepwise variable selection were fitted to examine the effect of several fertility variables on expectation of survival times. RESULTS: Virgin females displayed higher life expectancy than virgin males. The relative risk of dying for a virgin male at a particular age was 2.116 [99% confidence interval: 1.317, 3.398] times that of a virgin female. No significant differences on expectation of survival times between virgin and mated females, and between virgin and mated males were found. Furthermore, total number of pups at weaning and total number of litters produced by a dam/stud, time interval between mating and last litter, time interval between litters, and age at last litter were not significant predictors of expectation of survival times in both mated females and mated males. CONCLUSIONS: Like in most human studies, the present study evidences no relationship between total number of offspring/litters produced by a dam/stud and expectation of survival times. Moreover, the present data are in agreement with the general phenomenon of a bias in life expectancy in favor of females.
Asunto(s)
Envejecimiento , Longevidad , Modelos Biológicos , Embarazo/fisiología , Animales , Cruzamientos Genéticos , Femenino , Fertilidad , Número de Embarazos , Masculino , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Paridad , Reproducción , Caracteres Sexuales , Análisis de SupervivenciaRESUMEN
We analyzed the effect of in vitro aging of mouse oocytes in the presence of dithiothreitol (DTT) on relative levels of glutathione S-transferase (GST) activity and thiols in oocytes, and cell number, DNA fragmentation and cellular allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage at the blastocyst stage. Ovulated oocytes from gonadotropin primed hybrid female mice of 6-8 weeks of age were aged in vitro in the presence of 0, 5, 50, or 500 microM DTT for 6 hr prior to insemination. Relative levels of GST activity and thiols in oocytes were determined by confocal laser scanning microscopy, DNA fragmentation using a single-step TUNEL method, and cell allocation to the ICM and TE lineage by blastocyst staining with propidium iodide and Hoechst 33258. Non-aged oocytes exhibited higher relative levels of GST activity and thiols when compared to oocytes aged in the presence of 0, 5, and 50 microM DTT. Day 5 blastocysts from the 5, 50, and 500 microM DTT groups exhibited higher total number of cells, number of ICM cells, and ICM/TE ratio, but lower percentage of number of nuclei with DNA fragmentation/number of ICM cells than blastocyst from the 0 microM DTT group. These data show that DTT counteracts the negative effects of a post-ovulatory aging of mouse oocytes in vitro on relative levels of GST activity and thiols in oocytes, and percentage of number of nuclei with DNA fragmentation/number of ICM cells, total number of cells, number of ICM cells and ICM/TE ratio in Day 5 blastocysts.
Asunto(s)
Blastocisto , Fragmentación del ADN , Ditiotreitol/metabolismo , Glutatión Transferasa/metabolismo , Oocitos/fisiología , Compuestos de Sulfhidrilo/metabolismo , Animales , Blastocisto/citología , Blastocisto/fisiología , Femenino , Fertilización In Vitro , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Oocitos/citologíaRESUMEN
This study analyzes the long-term effects of delayed motherhood on reproductive fitness and life expectancy of offspring in the mouse. Hybrid (C57BL/6JIco x CBA/JIco) first-generation (F1) females, either at the age of 10 or 51 wk, were individually housed with a randomly selected 12- to 14-wk-old hybrid male following a breeding pen system until females reached the end of their reproductive life. Reproductive fitness of second-generation (F2) females was tested from the age of 25 wk until the end of their reproductive life. In F2 males, the testing period ranged from the age of 52 wk until their natural death. Delayed motherhood of hybrid F1 female mice was associated with a decreased percentage of male F3 offspring at birth and lower life expectancy and body weight during adulthood of F2 offspring. There was, however, no evident negative effect of delayed motherhood on several reproductive fitness variables in either male or female F2 offspring. This included between-parturition interval, litter size at birth and at weaning, body weight at weaning and preweaning mortality of F3 pups, percentage of F3 litters with at least one pup cannibalized, and time at which female and male F2 offspring ceased their reproductive life. These data clearly show that delayed motherhood in the mouse is associated with negative long-term effects on offspring survival.
Asunto(s)
Esperanza de Vida , Reproducción/fisiología , Animales , Peso Corporal , Femenino , Tamaño de la Camada , Longevidad , Masculino , Ratones , Ratones Endogámicos , Embarazo , Razón de MasculinidadRESUMEN
This study aims to determine in the mouse whether oocytes from reproductively old females exhibit a different susceptibility to be parthenogenetically activated when compared to oocytes from young females. At the age of 10-12 (young-female group) or 60-62 (old-female group) weeks, hybrid female mice were superovulated using pregnant mare's serum gonadotropin (PMSG) followed by human chorionic gonadotropin (hCG) 48 hr later. After removing the cumulus cells, oocytes were exposed to any of two different activating protocols: (a) 6-min exposure to 8% ethanol; and (b) treatment with 200 microM thimerosal for 15 min followed by 8 mM dithiothreitol (DTT) for 30 min. Oocytes from old female mice displayed (1) lower total percentage of parthenogenetic activation and extrusion of the second polar body after treatment with either thimerosal + DTT or ethanol; (2) higher M-phase-promoting factor (MPF) and mitogen-activated protein kinases (MAPKs) activities; and (3) lower intracytoplasmic levels of glutathione S-transferases (GSTs) activity and thiols than oocytes from young females. These data show that female aging is associated with higher resistance of oocytes to be parthenogenetically activated, higher MPF and MAPKs activities and lower intracytoplasmic levels of GSTs activity and thiols.
Asunto(s)
Envejecimiento/fisiología , Factor Promotor de Maduración/metabolismo , Oocitos/fisiología , Animales , Femenino , Glutatión Transferasa/metabolismo , Humanos , Sistema de Señalización de MAP Quinasas/fisiología , Masculino , Mesotelina , Ratones , Partenogénesis/fisiología , Factores Sexuales , Compuestos de Sulfhidrilo/metabolismoRESUMEN
BACKGROUND: Some epidemiological evidence tentatively suggests that children born to older parents may have lower intellectual development and maturity than children whose parents are younger. This study aims to analyse the long-term effects of delayed motherhood in mice on postnatal development and behavioural traits later in life. METHODS: Hybrid females, either at the age of 10 weeks or 51 weeks, were individually housed with a randomly selected 12-14 week old hybrid male. After a postweaning resting period of 1 week, dams were caged again with a new randomly selected 12-14 week old male. This sequence of events was repeated until old females reached the end of their reproductive life. RESULTS: Delayed motherhood in mice not only had negative effects on reproductive potential but also on preweaning development of offspring as evidenced by higher mortality, retarded sensorimotor integration and lower body weights as well as on behavioural traits of young adult offspring including decreased spontaneous motor activity, lower step-through latencies in the retention trial of a passive avoidance behaviour test, and no changes in escape latencies throughout five daily sessions in a Morris water maze test. CONCLUSION: Advanced maternal age at conception may influence preweaning development and learning capacity of offspring in the mouse model.
Asunto(s)
Conducta Animal , Reproducción , Animales , Reacción de Prevención , Aprendizaje Discriminativo , Femenino , Crecimiento , Humanos , Edad Materna , Aprendizaje por Laberinto , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Modelos Animales , Actividad Motora , Embarazo , Conducta ReproductivaRESUMEN
The present study aims to analyze the cause-effect relationships among several in-vitro fertilization and pre-implantation embryo development variables in the mouse. Superovulation of hybrid (C57Bl/6JIco female X CBA/JIco male) female mice of 4-6 weeks of age was induced by a priming injection of pregnant mare's serum gonadotropin at the estrus stage of the estrous cycle followed after a 48-hr interval by human chrorionic gonadotropin. Ovulated cumulus-enclosed oocytes were inseminated with sperm from hybrid males of 12-16 weeks of age. The multiple linear regression analyses performed indicated that (a) total number of ovulated oocytes is a good predictor of both fertilization frequency and total number of cells in day-5 blastocysts; (b) fertilization frequency predicts percentage of day-5 blastocysts; (c) total number of cells in day-5 blastocysts is predicted by percentage of day-5 blastocysts; and (d) total number of cells in day-5 blastocysts predicts percentage of apoptotic cells, number of inner cell mass (ICM) and trophectoderm (TE) cells, and ICM/TE ratio in day-5 blastocysts. Mitotic index in day-5 blastocysts was positively correlated with total number of ovulated oocytes, percentage of ovulated cumulus-enclosed oocytes, fertilization frequency, percentage of day-5 blastocysts and total number of cells in day-5 blastocysts. On the contrary, it was negatively correlated with percentage of apoptotic cells in day-5 blastocysts.
Asunto(s)
Blastocisto/fisiología , Desarrollo Embrionario y Fetal , Fertilización In Vitro , Ratones/embriología , Animales , Apoptosis , Recuento de Células , División Celular , Cruzamientos Genéticos , Femenino , Modelos Lineales , Masculino , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Índice Mitótico , OvulaciónRESUMEN
This article aims to throw light on the controversial topic of whether women have a 'heat' period within their menstrual cycle. The majority of publications in this field report, in addition to a periovulatory peak, no changes at all or even rises in male- and female-initiated sexual activity, woman's sexual desire, autosexual activity and sexual arousability, and interpersonal sexual activities during the mid-follicular and late luteal phases. The lack of a distinct pattern of women's sexual behaviour across the menstrual cycle may be explained by the interplay between cyclical endocrine fluctuations and many psychological, social, cultural and environmental factors, as well as the methodological shortcomings associated with menstrual cycle research. However, studies focused on cycling changes in women's olfactory and visual perception show that, in comparison with women at other phases of the menstrual cycle, women at mid-cycle exhibit increased sexual motivation that biases recognition performance towards objects with a sexual meaning, evaluate the unattractive sweat substance androstenone as more pleasant, and display enhanced preference for the odour and face shape of masculinized, physically attractive and symmetric men. On the other hand, men find the scent of women at mid-cycle more pleasant and sexually attractive than during the luteal phase.
Asunto(s)
Ciclo Menstrual/psicología , Conducta Sexual/fisiología , Señales (Psicología) , Femenino , Humanos , Masculino , Ciclo Menstrual/fisiología , Odorantes , Percepción Visual/fisiologíaRESUMEN
The present study aims to analyze in the mouse the effect of the stage of the estrous cycle at the time of pregnant mare's serum gonadotropin (PMSG) injection on fertilization of ovulated cumulus-enclosed oocytes and later embryo development in vitro to the blastocyst stage. Quality of blastocysts was evaluated by staining and counting of total number of nuclei, mitotic index, percentage of apoptotic nuclei, and cell allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage. Superovulation of hybrid (C57Bl/6JIco female x CBA/JIco male) female mice of 4-6 weeks of age was induced by a priming injection of PMSG at different stages of the estrous cycle followed after a 48-hr interval by human chrorionic gonadotropin. Our data indicate that injection of PMSG at the estrus phase gives the best outcome whereas injection of PMSG at the diestrus-1 or diestrus-2 phase provides the worst results. In fact, (1) total number of oocytes ovulated, number of ovulated oocytes enclosed by cumulus cells, and number of TE cells in day-5 blastocysts were significantly lower in diestrus-1 females than in estrus, diestrus-2 and proestrus mice; (2) percentage of day-5 blastocysts and total number of cells in day-5 blastocysts were lower in diestrus-1 and diestrus-2 females than in estrus and proestrus mice; and (3) percentage of apoptotic nuclei in day-5 blastocysts was lower in estrus mice than in diestrus-1, diestrus-2, or proestrus females. These data endorse previous studies suggesting that administration of gonadotropins in mice should be synchronized with the innate estrous cycle of females.