Long-term and transgenerational effects of cryopreservation on rabbit embryos

The short-term effects of cryopreservation and embryo transfer are well documented (reduced embryo viability, changes in pattern expression), but little is known about their long-term effects. We examined the possibility that embryo vitrification and transfer in rabbit could have an impact on the long-term reproductive physiology of the offspring and whether these phenotypes could be transferred to the progeny. Vitrified rabbit embryos were warmed and transferred to recipient females (F0). The offspring of the F0 generation were the F1 generation (cryopreserved animals). Females from F1 generation offspring were bred to F1 males to generate an F2 generation. In addition, two counterpart groups of noncryopreserved animals were bred and housed simultaneously to F1 and F2 generations (CF1 and CF2, respectively). The reproductive traits studied in all studied groups were litter size (LS), number born alive at birth (BA), and postnatal survival at Day 28 (number of weaned/number born alive expressed as percentage). The reproductive traits were analyzed using Bayesian methodology. Features of the estimated marginal posterior distributions of the differences between F1 and their counterparts (F1 − CF1) and between F2 and their counterparts (F2 − CF2) in reproductive characters found that vitrification and transfer procedures cause a consistent increase in LS and BA between F1 and CF1 females (more than 1.4 kits in LS and more than 1.3 BA) and also between F2 and CF2 females (0.96 kits in LS and 0.94 BA). We concluded that embryo cryopreservation and transfer procedures have long-term effects on derived female reproduction (F1 females) and transgenerational effects on female F1 offspring (F2 females).     

Neonatal immune challenge alters reproductive development in the female rat

This article is part of a Special Issue "Neuroendocrine-Immune Axis in Health and Disease." Neonatal lipopolysaccharide (LPS) exposure alters neuroendocrine, immune and behavioural responses in adult rats. Recent findings indicate that neonatal LPS treatment may have a more pronounced effect on the mating behaviours of females compared to males. The current study further explored the impact of neonatal inflammation on reproductive development in the female rat. Wistar rats were administered LPS (0.05mg/kg, i.p.) or saline (equivolume) on postnatal days (PNDs) 3 and 5. The immediate effect of treatment was assessed on plasma corticosterone and tyrosine hydroxylase (TH) phosphorylation in the adrenal medulla. Weight gain and vaginal opening were recorded, and oestrous cyclicity was monitored post-puberty and in late adulthood. Blood and ovaries were collected throughout development to assess HPA and HPG hormones and to examine ovarian morphology. Reproductive success in the first (F1) generation and reproductive development in the second (F2) generation were also assessed. Neonatal LPS exposure resulted in increased TH phosphorylation in the neonatal adrenals. LPS treatment increased the corticosterone concentrations of females as juveniles, adolescents and adults, and reduced FSH in adolescence. Increased catch-up growth was evident in LPS-treated females, prompting earlier onset of puberty. Diminished follicular reserve was observed in neonatally LPS-treated females along with the advanced reproductive senescence. While fertility rates were not compromised, higher mortality and morbidity were observed in litters born to LPS-treated mothers. Female offspring of LPS-treated mothers displayed increased corticosterone on PND 14, increased catch-up growth and delayed emergence of the first oestrous cycle. No differences in any of the parameters assessed were observed in F2 males. These data suggest that neonatal immunological challenge has a profound impact on the female reproductive development, via the alteration of metabolic and neuroendocrine factors which regulate sexual maturation. Evidence of altered development in the female, but not male offspring of LPS-treated dams suggests increased susceptibility of females to the deleterious effects of neonatal immunological stress and its possible transferability to a subsequent generation.     

Two generation reproduction study of styrene by inhalation in Crl-CD rats

This study was conducted to evaluate the potential adverse effects of styrene on reproductive capability from whole-body inhalation exposure of F0 and F1 parental animals. Assessments included gonadal function, estrous cyclicity, mating behavior, conception rate, gestation, parturition, lactation, and weaning in the F0 and F1 generations, and F1 generation offspring growth and development. Four groups of male and female Crl:CD(SD)IGS BR rats (25/sex/group) were exposed to 0, 50, 150, and 500 ppm styrene for 6 hr daily for at least 70 consecutive days prior to mating for the F0 and F1 generations. Inhalation exposure for the F0 and F1 females continued throughout mating and gestation through gestation day 20. Inhalation exposure of the F0 and F1 females was suspended from gestation day 21 through lactation day 4. On lactation days 1 through 4, the F0 and F1 females received styrene in virgin olive oil via oral gavage at dose levels of 66, 117, and 300 mg/kg/day (divided into three equal doses, approximately 2 hr apart). These oral dosages were calculated to provide similar maternal blood peak concentrations as provided by the inhalation exposures. Inhalation exposure of the F0 and F1 females was re-initiated on lactation day 5. Styrene exposure did not affect survival or clinical observations. Rats in the 150- and 500-ppm groups in both parental generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either the F0 or F1 generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, reproductive organ weights, lengths of estrous cycle and gestation, live litter size and postnatal survival were similar in all exposure groups. Additionally, ovarian follicle counts and corpora lutea counts for the F1 females in the high-exposure group were similar to the control values. No adverse exposure-related macroscopic pathology was noted at any exposure level in the F0 and F1 generations. A previously characterized pattern of degeneration of the olfactory epithelium that lines the dorsal septum and dorsal and medial aspects of the nasal turbinates occurred in the F0 and F1 generation animals from the 500-ppm group. In the 500-ppm group, F2 birthweights were reduced compared to the control and F2 offspring from both the 150- and 500-ppm exposure groups gained weight more slowly than the controls. Based on the results of this study, an exposure level of 50 ppm was considered to be the NOAEL for F0 and F1 parental systemic toxicity; the NOAEL for F0 and F1 reproductive toxicity was 500 ppm or greater.     

Anxiety-like behaviors in adulthood are altered in male but not female rats exposed to low dosages of polychlorinated biphenyls in utero

Exposure to polychlorinated biphenyls (PCBs), a class of endocrine-disrupting chemicals, can result in altered reproductive behavior in adulthood, especially when exposure occurs during critical periods of brain sexual differentiation in the fetus. Whether PCBs alter other sexually dimorphic behaviors such as those involved in anxiety is poorly understood. To address this, pregnant rat dams were injected twice, on gestational days 16 and 18, with the weakly estrogenic PCB mixture Aroclor 1221 (A1221) at one of two low dosages (0.5 mg/kg or 1.0 mg/kg, hereafter 1.0 and 0.5), estradiol benzoate (EB; 50 μg/kg) as a positive estrogenic control, or the vehicle (3% DMSO in sesame oil). We also conducted a comprehensive assessment of developmental milestones of the F1 male and female offspring. There were no effects of treatment on sex ratio at birth and age at eye opening. Puberty, assessed by vaginal opening in females and preputial separation in males, was not affected in females but was advanced in males treated with A1221 (1.0). Males and females treated with A1221 (both dosages) were heavier in early adulthood relative to controls. The earliest manifestation of this effect developed in males prior to puberty and in females slightly later, during puberty. Anxiety-like behaviors were tested using the light:dark box and elevated plus maze tests in adulthood. In females, anxiety behaviors were unaffected by treatment. Males treated with A1221 (1.0) showed reduced indices of anxiety and increased activity in the light:dark box but not the elevated plus maze. EB failed to replicate the phenotype produced by A1221 for any of the developmental and behavioral endpoints. Collectively, these results indicate that PCBs increase body weight in both sexes, but their effects on anxiety-like behaviors are specific to males. Furthermore, differences between the results of A1221 and EB suggest that the PCBs are likely acting through mechanisms distinct from their estrogenic activity.     

The effects of prenatal PCBs on adult female paced mating reproductive behaviors in rats

Polychlorinated biphenyls (PCBs) are a family of toxicants that persist in measurable quantities in human and wildlife tissues, despite their ban in production in 1977. Some PCB mixtures can act as endocrine disrupting chemicals (EDCs) by mimicking or antagonizing the actions of hormones in the brain and periphery. When exposure to hormonally active substances such as PCBs occurs during vulnerable developmental periods, particularly prenatally or in early postnatal life, they can disrupt sex-specific patterning of the brain, inducing permanent changes that can later be manifested as improper sexual behaviors. Here, we investigated the effects of prenatal exposure to the PCB mixture Aroclor (A) 1221 on adult female reproductive behaviors in a dose-response model in the Sprague-Dawley rat. Using a paced mating paradigm that permits the female to set the timing of mating and control contact with the male during copulation, we were able to uncover significant differences in female-typical sexual activities in A1221-exposed females. Specifically, A1221 causes significant effects on mating trial pacing, vocalizations, ambulation and the female's likelihood to mate. The results further demonstrate that the intermediate treatment group has the greatest number of disrupted endpoints, suggestive of non-linear dose responses to A1221. These data demonstrate that the behavioral phenotype in adulthood is disrupted by low, ecologically relevant exposures to PCBs, and the results have implications for reproductive success and health in wildlife and women.     

The Mechanism of Environmental Endocrine Disruptors (DEHP) Induces Epigenetic Transgenerational Inheritance of Cryptorchidism

Discussion on the role of DEHP in the critical period of gonadal development in pregnant rats (F0), studied the evolution of F1-F4 generation of inter-generational inheritance of cryptorchidism and the alteration of DNA methylation levels in testis. Pregnant SD rats were randomly divided into two groups: normal control group and DEHP experimental group. From pregnancy 7d to 19d, experimental group was sustained to gavage DEHP 750mg/kg bw/day, observed the incidence of cryptorchidism in offspring and examined the pregnancy rate of female rats through mating experiments. Continuous recording the rat’s weight and AGD value, after maturation (PND80) recording testis and epididymis’ size and weight, detected the sperm number and quality. Subsequently, we examined the evolution morphological changes of testicular tissue for 4 generation rats by HE staining and Western Blot. Completed the MeDIP-sequencing analysis of 6 samples (F1 generation, F4 generation and Control). DEHP successfully induced cryptorchidism occurrence in offspring during pregnancy. The incidence of cryptorchidism in F1 was 30%, in F2 was 12.5%, and there was no cryptorchidism coming up in F3 and F4. Mating experiment shows conception rate 50% in F1, F2 generation was 75%, the F3 and F4 generation were 100%. HE staining showed that the seminiferous epithelium of F1 generation was atrophy and with a few spermatogenic cell, F2 generation had improved, F3 and F4 generation were tend to be normal. The DNA methyltransferase expression was up-regulated with the increase of generations by Real Time-PCR, immunohistochemistry and Western Blot. MeDIP-seq Data Analysis Results show many differentially methylated DNA sequences between F1 and F4. DEHP damage male reproductive function in rats, affect expression of DNA methyltransferase enzyme, which in turn leads to genomic imprinting methylation pattern changes and passed on to the next generation, so that the offspring of male reproductive system critical role in the development of imprinted genes imbalances, and eventually lead to producing offspring cryptorchidism. This may be an important mechanism of reproductive system damage.     

Two-generation reproduction study of di-2-ethylhexyl terephthalate in Crl:CD rats

BACKGROUND: This study was conducted to evaluate the potential adverse effects of di-2-ethylhexyl terephthalate (DEHT) on reproductive capability from exposure of F(0) and F(1) parental animals. METHODS: Four groups of male and female Crl:CD (SD)IGS BR rats (30/gender/group) were exposed to 0, 0.3%, 0.6%, and 1.0% DEHT in the feed for at least 70 consecutive days before mating for the F(0) and F(1) generations. Exposure for the F(0) and F(1) males continued throughout the mating period until euthanasia. Exposure for the F(0) and F(1) females continued throughout mating, gestation, and lactation. The F(1) and F(2) pups were weaned on postnatal day (PND) 21. Assessments included gonadal function, estrous cyclicity, mating behavior, conception rate, gestation, parturition, lactation, and weaning in the F(0) and F(1) generations, and F(1) generation offspring growth and development. RESULTS: DEHT exposure did not affect clinical observations. However, lethality was observed in F(0) and F(1) dams consuming the 1.0% diet during the post-weaning period. No treatment-related mortality occurred in any of the male groups exposed to DEHT or in the female groups exposed to 0.3% or 0.6% DEHT. Male rats consuming the 1.0% diet in both parental generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either the F(0) or F(1) generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, reproductive organ weights, lengths of estrous cycle and gestation, live litter size, developmental landmarks, and postnatal survival were similar in all exposure groups. Additionally, ovarian follicle counts for the F(1) females in the high-exposure group were similar to the control values. No adverse exposure-related macroscopic pathology was noted at any exposure level in the F(0) and F(1) generations. CONCLUSIONS: Increases in liver weights were found in the male and female animals exposed to 0.6% or 1.0% DEHT in the diet. Because there were no accompanying histopathologic changes, this effect was not considered adverse. Significant decreases in feed consumption in the female animals from the groups consuming 1.0% DEHT in the diet during lactation accompanied reduced postnatal pup body weights and rate of weight gain. Reductions in pup body weights later in lactation may also have been due to direct consumption of the treated feed by the pups or taste aversion to the same. Reduced relative spleen weight was found in male weanling pups from the 1.0% group in both generations and reduced relative spleen and thymus weights were found in female pups from the 1.0% group in the F(2) generation at necropsy on PND 21. Therefore, for parental and pup systemic toxicity, 0.3% DEHT in the diet (182 mg/kg/day) was considered no-observed-effect level (NOEL). The 1.0% DEHT (614 mg/kg/day) in the diet exposure concentration was considered a NOEL for F(0) and F(1) reproductive toxicity endpoints.     

Effects of p-nonylphenol and resveratrol on body and organ weight and in vivo fertility of outbred CD-1 mice

The aim of this study was to analyse the multigenerational effects of para-nonylphenol (NP) and resveratrol (RES) on the body weight, organ weight and reproductive fitness of outbred CD-1 mice. The data indicate that in male mice, NP had an effect on the weight of selected reproductive organs and the kidneys in the parental (P) generation males. Effects on selected reproductive organs, the liver and kidneys in the F1-generation males were also seen. In females, effects of NP on body weight and kidney weight were seen in the P generation, but no effects on any measured parameter were seen in the F1 generation. RES had no effect on body weight but did have some effect on selected male and female reproductive organs in the P generation. RES altered the spleen and liver weights of P-generation males and the kidney weight of F1-generation males. Acrosomal integrity (using a monoclonal antibody against intra-acrosomal sperm proteins) was assessed for both generations of NP- and RES-treated mice. A significant reduction in acrosomal integrity was seen in both generations of NP-treated, but not in RES-treated, mice. Fewer offspring were observed in the second litter of the F2 generation of mice treated with NP; no similar effect was seen in RES-treated mice. The litter sex ratio was not different from controls. Unlike RES, NP had a negative effect on spermatogenesis and sperm quality with a resultant impact on in vivo fertility.     

Lack of effects on fertility and developmental toxicity of a quadrivalent HPV vaccine in Sprague‐Dawley rats

Human papillomavirus (HPV) infection is one of the most common sexually transmitted diseases, with approximately half of the HPV‐infected people being adolescents and young adults. A recently developed quadrivalent HPV vaccine, GARDASIL^®, has been shown to be highly effective in the prevention of a number of HPV‐mediated diseases. The objective of the present study was to evaluate the potential effects of the vaccine on female fertility and F1 development, growth, behavior, and reproductive performance. In addition, anti‐HPV antibodies in the F0 females and F1 offspring were measured during the study. Two groups of 65 virgin Sprague‐Dawley rats were administered two or four intramuscular injections of the vaccine (full human dose of 0.5 mL at 5 and 2 weeks prior to mating, on Gestation Day [GD] 6, and Lactation Day [LD] 7; or GD 6 and LD 7 only). Additional groups of rats were administered phosphate‐buffered saline or Merck Aluminum Adjuvant (MAA) at the same four times. All females were mated to males of the same stock. Cesarean sections were performed on 22/group on GD 21, 22/group were allowed to deliver, and remaining females used for blood collections or replacements. F0 female fertility parameters were evaluated. An extensive number of prenatal, perinatal, and postnatal parameters were evaluated in the F1 generation. There were no unscheduled deaths during the study. There was no evidence of toxicity in the F0 females given either MAA or vaccine. There were no effects on the fertility or reproductive performance of the F0 females. There was no evidence of developmental toxicity to the F1 generation, including fetal body weight and morphology, postnatal growth and development, behavior, and reproductive performance. The quadrivalent vaccine induced a specific antibody response to the four HPV types in the F0 female rats following one or multiple injections. Antibodies against all four HPV types were transferred to the F1 generation during gestation and/or lactation, likely via the placenta and milk, respectively. The passively transferred antibodies persisted up to Postnatal Day 77 when they were last measured. These results demonstrate that this quadrivalent HPV vaccine had no detectable adverse effects in either the treated F0 female rats or the F1 generation. Birth Defects Res (Part B) 83:561–572, 2008. © 2008 Wiley‐Liss, Inc.     

Inhalation developmental neurotoxicity study of ethylbenzene in Crl-CD rats

BACKGROUND: This study was conducted to evaluate the potential adverse effects of whole-body inhalation exposure of F0 and F1 parental animals from a 2-generation reproduction study of ethylbenzene on nervous system functional and/or morphologic end points in the F2 offspring from four groups of male and female Crl:CD (SD)IGS BR rats. METHODS: Thirty rats/sex/group for F0 and 25/sex/group for F1 were exposed to 0, 25, 100, and 500 ppm ethylbenzene for six hours daily for at least 70 consecutive days prior to mating for the F0 and F1 generations. Inhalation exposure for the F0 and F1 females continued throughout mating and gestation through Gestation Day (GD) 20. On lactation days (LD) 1-4, the F0 and F1 females received no inhalation exposure, but instead were administered ethylbenzene in corn oil via oral gavage at dosages estimated to result in similar internal maternal exposure based upon PBPK modeling estimates (0, 26, 90, and 342 mg/kg/day, respectively, divided into three equal doses, approximately two hours apart). Inhalation exposure of the F0 and F1 females was reinitiated on LD 5 and continued through weaning on postnatal day (PND) 21. Survival, body weights, and physical landmarks were assessed in selected F2 offspring. Neurobehavioral development of one F2-generation treatment derived offspring/sex/litter was assessed in a functional observational battery (FOB; PND 4, 11, 22, 45, and 60), motor activity sessions (PND 13, 17, 21, and 61), acoustic startle testing (PND 20 and 60), a Biel water maze learning and memory task (initiated on PND 26 or 62), and in evaluations of whole-brain measurements and brain morphometric and histologic assessments (PND 21 and 72). RESULTS: There were no adverse effects on reproductive performance in either the F0 or F1 parental generations exposed to up to 500 ppm ethylbenzene [Faber et al. Birth Defects Res Part B 77:10-21, 2006]. In the current developmental neurotoxicity component, parental ethylbenzene exposure did not adversely affect offspring survival, clinical condition, body weight parameters, or acquisition of developmental landmarks of the F2-generation treatment derived offspring. There were no alterations in FOB parameters, motor activity counts, acoustic startle endpoints, or Biel water maze performance in offspring attributed to parental ethylbenzene exposure. A few isolated instances of statistically significant differences obtained in the treatment-derived groups occurred sporadically, and were attributed to unusual patterns of development and/or behavior in the concurrent control group. There were no exposure-related differences in any neuropathology parameters in the F2-generation treatment derived offspring. CONCLUSIONS: The no observed adverse effect level (NOAEL) for maternal reproductive toxicity, developmental toxicity, and developmental neurotoxicity in this study was considered to be 500 ppm/342 mg/kg/day ethylbenzene, the highest exposure level tested in the study.     

Safety of a novel oxygen-coordinated niacin-bound chromium(III) complex (NBC): I. Two-generation reproduction toxicity study

The objective of this study was to evaluate the effects of a novel oxygen-coordinated niacin-bound chromium(III) complex (NBC) on the reproductive systems of male and female rats, the postnatal maturation and reproductive capacity of their offspring, and possible cumulative effects through multiple generations. Sprague-Dawley rats were maintained on feed containing NBC at dose levels of 0, 4, 15, or 60 ppm for 10 weeks prior to mating, during mating, and, for females through gestation and lactation, across two generations. For the parents (F₀ and F₁) and the offspring (F₁ and F_2a), reproductive parameters such as fertility and mating, gestation, parturition, litters, lactation, sexual maturity and development of offspring were assessed. Results from the current study indicated that dietary exposure of NBC to parental male and female rats of both (F₀ and F₁) the generations during the premating and mating periods, for both sexes, and during gestation and lactation in case of female rats, did not cause any significant incidence of mortality or abnormal clinical signs. Compared to respective controls, NBC exposure did not affect reproductive performance as evaluated by sexual maturity, fertility and mating, gestation, parturition, litter properties, lactation and development of the offspring. Based on the findings of this study, the parental as well as the offspring no-observed-adverse-effect level for NBC was determined to be greater than 60 ppm in diet or equivalent to 7.80 and 8.31 mg/kg body weight/day in male and female rats, respectively.     

Effects of male courtship and gonadal steroids on pair formation, egg-laying, and serum LH in Canvasback ducks (Aythya valisineria)

The effects of social stimuli on the reproductive physiology of female birds have been widely studied. This study examined the endocrine and behavioural responses of female Canvasbacks ( Aythya valisineria ) to changes in the behavioural and endocrine states of the male, as signalled by his courtship displays. Male Canvasbacks exposed to female conspecifics exhibited a variety of courtship displays which increased significantly with testosterone administration. However, the testosterone-increased courtship displays of males did not increase female receptivity or serum LH, or stimulate reproductive development or egg-laying in unpaired females placed with them. Females confined in cubicles within a pen that held breeding pairs and a free-swimming flock had higher serum LH levels and laid more eggs than did females in cubicles in another pen without breeding pairs or a free-swimming flock. This suggests that social factors, such as vocalizations from a flock and breeding pairs, may increase serum LH and egg-laying in unpaired females. Oestradiol implants in female Canvasbacks did not elevate receptivity to courting drakes, nor did they stimulate pair formation, nesting activity, or egg-laying behaviour. Testosterone implants in drakes and oestradiol implants in females decreased serum LH in each group. These results show that increasing the amount of courtship is not adequate to stimulate pairing behaviour or increases in reproductive hormones. Thus, our results suggest that female receptivity to male courtship may be a key determinant of pair formation and consequent synchronization of the behaviour patterns between members of a pair of wild birds. Our results may further suggest a dissociation between effects of courtship and pair formation in wild Canvasbacks.     

Developmental neurotoxicity study of styrene by inhalation in Crl-CD rats

This study was conducted to assess potential adverse functional and/or morphological effects of styrene on the neurological system in the F2 offspring following F0 and F1 generation whole-body inhalation exposures. Four groups of male and female Crl:CD (SD)IGS BR rats (25/sex/group) were exposed to 0, 50, 150, and 500 ppm styrene for 6 hr daily for at least 70 consecutive days prior to mating for the F0 and F1 generations. Inhalation exposure continued for the F0 and F1 females throughout mating and through gestation day 20. On lactation days 1 through 4, the F0 and F1 females received styrene in virgin olive oil via oral gavage at dose levels of 66, 117, and 300 mg/kg/day (divided into three equal doses, approximately 2 hr apart). Inhalation exposure of the F0 and F1 females was re-initiated on lactation day 5 and continued through weaning of the F1 or F2 pups on postnatal day (PND) 21. Developmental landmarks were assessed in F1 and F2 offspring. The neurological development of randomly selected pups from the F2 generation was assessed by functional observational battery, locomotor activity, acoustic startle response, learning and memory evaluations, brain weights and dimension measurements, and brain morphometric and histologic evaluation. Styrene exposure did not affect survival or the clinical condition of the animals. As expected from previous studies, slight body weight and histopathologic effects on the nasal olfactory epithelium were found in F0 and F1 rats exposed to 500 ppm and, to a lesser extent, 150 ppm. There were no indications of adverse effects on reproductive performance in either the F0 or F1 generation. There were exposure-related reductions in mean body weights of the F1 and F2 offspring from the mid and high-exposure groups and an overall pattern of slightly delayed development evident in the F2 offspring only from the 500-ppm group. This developmental delay included reduced body weight (which continued through day 70) and slightly delayed acquisition of some physical landmarks of development. Styrene exposure of the F0 and F1 animals had no effect on survival, the clinical condition or necropsy findings of the F2 animals. Functional observational battery evaluations conducted for all F1 dams during the gestation and lactation periods and for the F2 offspring were unaffected by styrene exposure. Swimming ability as determined by straight channel escape times measured on PND 24 were increased, and reduced grip strength values were evident for both sexes on PND 45 and 60 in the 500-ppm group compared to controls. There were no other parental exposure-related findings in the F2 pre-weaning and post-weaning functional observational battery assessments, the PND 20 and PND 60 auditory startle habituation parameters, in endpoints of learning and memory performance (escape times and errors) in the Biel water maze task at either testing age, or in activity levels measured on PND 61 in the 500-ppm group. Taken together, the exposure-related developmental and neuromotor changes identified in F2 pups from dams exposed to 500 ppm occurred in endpoints known to be both age- and weight-sensitive parameters, and were observed in the absence of any other remarkable indicators of neurobehavioral toxicity. Based on the results of this study, an exposure level of 50 ppm was considered to be the NOAEL for growth of F2 offspring; an exposure level of 500 ppm was considered to be the NOAEL for F2 developmental neurotoxicity.     

Delayed motherhood decreases life expectancy of mouse offspring

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.     

滞育烟蚜茧蜂的亲代效应评价

【目的】烟蚜茧蜂Aphidius gifuensis Ashmead是可持续防控蚜虫的优良内寄生蜂,适宜的低温短光照可诱导其进入滞育,滞育后产品货架期长达120 d,对害虫生防意义重大。为深入探索滞育烟蚜茧蜂的亲代效应,分析滞育机理,提高滞育诱导效率,指导该天敌产品的贮存实践,开展本项研究。【方法】在室内测试了滞育烟蚜茧蜂F1代的羽化率、性比、成蜂寿命、滞育率、寄生力以及F2代的羽化率、性比等生物学指标,综合评价滞育烟蚜茧蜂的亲代效应。【结果】滞育经历对烟蚜茧蜂子代的部分生物学性状具有显著性影响,F1代雌蜂比例显著增加,滞育维持30 d后子代雌蜂比例由0.59上升至0.65;F2代雌蜂比例与CK无差别,维持在0.58左右;F1代滞育率显著升高,可由对照的44.75%提高至74.01%,滞育维持30 d后子代滞育率具升高趋势;F1代寄生力略增加,各处理形成的僵蚜数在117~129头间,但无显著性差异;F1代羽化率、子代成蜂寿命与CK相比无差异。【结论】烟蚜茧蜂具有较显著的滞育亲代效应,亲代滞育经历可显著提高子一代的滞育率,利于子代抵御不良环境胁迫,提高种群存活率。     

Pre- and postnatal development studies of lasofoxifene, a selective estrogen receptor modulator (SERM), in Sprague-Dawley rats

BACKGROUND: Lasofoxifene is a nonsteroidal selective estrogen receptor modulator (SERM) developed for the treatment of postmenopausal osteoporosis. The purpose of these studies was to evaluate the effects of lasofoxifene on the postnatal development, behavior, and reproductive performance of offspring of female rats given lasofoxifene during organogenesis and lactation. METHODS: Two range-finding studies were conducted to determine the effects of lasofoxifene at doses from 0.01-10 mg/kg on parturition and lactation in pregnant rats and on the early postnatal development of the offspring, and to optimize the dosing regimen. Maternal milk and plasma were sampled for concentrations of lasofoxifene on Lactation Days 4, 7, and 14. In the pre- and postnatal development study, lasofoxifene was administered to pregnant and lactating rats by oral gavage at dose levels of 0.01, 0.03, and 0.1 mg/kg on Gestation Days 6-17 and Lactation Days 1-20. Maternal body weight and food consumption were measured throughout pregnancy, and body weight was measured throughout lactation. Parturition was monitored closely. The F1 offspring were measured for viability, body weight, anogenital distance, the appearance of postnatal developmental indices and reflex behaviors, sensory function, in an age-appropriate functional observational battery, motor activity, auditory startle, passive avoidance, and the Cincinnati Water Maze. The F1 generation was assessed for reproductive function, and the F2 offspring were measured for body weight and viability throughout the lactation period. RESULTS: In the range-finding studies, indications of maternal toxicity included decreased body weight and food consumption, increased length of gestation, prolonged parturition, dystocia, and increased offspring mortality at birth. Concentrations of lasofoxifene in maternal plasma were similar to those in milk, increased with increasing dose, and remained consistent over a 10-day period. In the pre- and postnatal development study, maternal body weights and food consumption were decreased in all treated groups during gestation. Length of gestation was increased, parturition was prolonged, and dystocia was noted in the dams in the 0.1 mg/kg group. There was increased pup mortality in the F1 litters in the 0.1 mg/kg group and all treated groups had decreased offspring body weights beginning at 1 week of age, continuing into the postweaning period and, for the F1 males, into adulthood. Female F1 offspring in the 0.03 and 0.1 mg/kg groups had increased body weights as adults. There were delays in the age of appearance of preputial separation in the males in the 0.1 mg/kg group and vaginal opening in the females in all treated groups. Body temperature was decreased by <0.5 degrees C after weaning for male and female offspring in the 0.1 mg/kg group. The sensory, behavioral, and functional measures, including the tests of learning and memory, were unaffected by treatment. Mating success was lower for the F1 animals in the 0.1 mg/kg group, but there were no effects on the reproductive parameters. Mating, reproduction, and maternal behavior of the F1 animals in the 0.01 and 0.03 mg/kg groups and the survival and body weights of the F2 offspring in all treated groups through Postnatal Day 21 were unaffected by treatment. CONCLUSION: The maternal findings in this study were related to the pharmacologic activity of lasofoxifene. Inhibition of growth of the F1 offspring after perinatal exposure to lasofoxifene was observed, but there were no significant effects on the sensory, behavioral, or functional measures, including learning and memory. There were no effects on the F2 generation. The findings are consistent with those reported for at least one other SERM. The findings of this study do not suggest increased risk for the primary indication of use in postmenopausal women.     

Postovulatory aging of oocytes decreases reproductive fitness and longevity of offspring.

We analyzed the long-term effects of postovulatory aging of mouse oocytes on reproductive fitness and longevity of offspring. Hybrid (C57BL/6JIco x CBA/JIco) parental generation (F0) females were artificially inseminated at 13 h (approximately 1 h postovulation) or 22 h (approximately 10 h postovulation) after GnRH injection. Reproductive fitness of first generation (F1) females was tested from the age of 28 wk until the end of their reproductive life. In males, the testing period ranged from the age of 2 yr until their natural death. Experimental F1 females exhibited longer between-labor intervals, decreased frequency of litters, and lower total number of litters and offspring born. Experimental second generation (F2) pups displayed teratogenic defects, higher preweaning mortality, and decreased body weight at weaning. Incidence of infertility was higher in experimental F1 males, which translated into lower total number of offspring born when compared with the control group. Life expectancy of F1 offspring was decreased in the experimental group. These results clearly show that postovulatory aging of mouse oocytes decreases reproductive fitness and longevity of offspring.     

Placental insufficiency leads to developmental hypertension and mesenteric artery dysfunction in two generations of Sprague-Dawley rat offspring

It is generally accepted that preeclampsia results from reduction in perfusion to the uteroplacental unit leading to maternal hypertension and fetal growth restriction. Placental insufficiency creates an environment of fetal undernutriton, predisposing the fetus to the development of adult disease. In this study, we characterized the development and perpetuation of hypertension in two generations of male and female offspring subjected to an environment of fetal undernutrition via reduced uteroplacental perfusion pressure. Further, we examined vascular responses of resistance arteries in these animals to determine the influence of placental insufficiency on the development and perpetuation of hypertension. Experimental dams underwent a surgical procedure to reduce uteroplacental perfusion pressure, with resulting offspring comprising the first generation (F1). One male and one female from each of the F1 experimental litters served as breeders of the second generation (F2). Weekly systolic blood pressure measurements were obtained from 4 to 24 wk in control, F1, and F2 offspring. Vascular responsiveness to the vasoconstrictors phenylephrine and potassium chloride and the vasorelaxants acetylcholine and sodium nitroprusside was determined in the three offspring groups at 6, 9, and 12 wk of age. Our findings indicate that placental insufficiency during a critical developmental window in late gestation leads to hypertension in juvenile Sprague-Dawley rat offspring and is perpetuated in a second generation of offspring in a gender-specific manner. Further, exposure to placental insufficiency during late gestation leads to developmental alterations characterized by vascular hyperresponsiveness, perpetuated to a second generation of offspring in the absence of persistent environmental stimuli, contributing to hypertension.     

Effect of Age,Duration of Exposure,and Dose of Atrazine on Sexual Maturation and the Luteinizing Hormone Surge in the Female Sprague–Dawley Rat

Atrazine (ATZ) was administered daily by gavage to pregnant female Sprague Dawley rats at doses of 0, 6.25, 25 or 50 mg/kg/day, either during gestation, lactation and post‐weaning (G/L/PW cohort) to F₁ generation female offspring or only from postnatal day (PND 21) until five days after sexual maturation (vaginal opening) when the estrogen‐primed, luteinizing hormone (LH) surge was evaluated (PW cohort). Additional subgroups of F₁ females received the vehicle or ATZ from PND 21–133 or from PND 120–133. Slight reductions in fertility and the percentage of F₁ generation pups surviving to PND 21 in the gestationally exposed 50 mg/kg dose group were accompanied by decreased food intake and body weight of dams and F₁ generation offspring. The onset of puberty was delayed in of the F₁ generation G/L/PW females at doses of 25 and 50 mg/kg/day. F₁ generation females in the PW high‐dose ATZ group also experienced a delay in the onset of puberty. ATZ had no effect on peak LH or LH AUC in ovariectomized rats 5 days after sexual maturation, irrespective of whether the F₁ generation females were treated from gestation onward or only peripubertally. There was no effect of ATZ treatment on the estrous cycle, peak LH or LH AUC of F₁ generation females exposed from gestation through to PND 133 or only for two weeks from PND 120–133. These results indicate that developing females exposed to ATZ are not more sensitive compared to animals exposed to ATZ as young adults     

Chemotherapy-induced late transgenerational effects in mice

To our knowledge, there is no report on long-term reproductive and developmental side effects in the offspring of mothers treated with a widely used chemotherapeutic drug such as doxorubicin (DXR), and neither is there information on transmission of any detrimental effects to several filial generations. Therefore, the purpose of the present paper was to examine the long-term effects of a single intraperitoneal injection of DXR on the reproductive and behavioral performance of adult female mice and their progeny. C57BL/6 female mice (generation zero; G0) were treated with either a single intraperitoneal injection of DXR (G0-DXR) or saline (G0-CON). Data were collected on multiple reproductive parameters and behavioral analysis for anxiety, despair and depression. In addition, the reproductive capacity and health of the subsequent six generations were evaluated. G0-DXR females developed despair-like behaviors; delivery complications; decreased primordial follicle pool; and early lost of reproductive capacity. Surprisingly, the DXR-induced effects in oocytes were transmitted transgenerationally; the most striking effects being observed in G4 and G6, constituting: increased rates of neonatal death; physical malformations; chromosomal abnormalities (particularly deletions on chromosome 10); and death of mothers due to delivery complications. None of these effects were seen in control females of the same generations. Long-term effects of DXR in female mice and their offspring can be attributed to genetic alterations or cell-killing events in oocytes or, presumably, to toxicosis in non-ovarian tissues. Results from the rodent model emphasize the need for retrospective and long-term prospective studies of survivors of cancer treatment and their offspring.