The functional importance of the oviduct in neonatally estrogenized mouse females for early embryo survival

Protocol for isolation of mouse pre-implantation embryos for gene expression analysis

Visualizing and quantifying the numerous factors that regulate murine pre-implantation embryonic development is technically challenging. Here, we present a protocol for the isolation of pre-implantation embryos at multiple stages of embryonic development to study gene expression. We describe steps for isolating RNA and cDNA synthesis from a small number of embryos. We then detail an immunofluorescence assay for the detection and localization of protein of interest by confocal microscopy in the pre-implantation embryos. For complete details on the use and execution of this protocol, please refer to Varghese et al.1.

New frontiers of developmental endocrinology opened by researchers connecting irreversible effects of sex hormones on developing organs

In the early 1960's, at Professor Bern's laboratory, University of California, Berkeley) in the US, Takasugi discovered ovary-independent, persistent vaginal changes in mice exposed neonatally to estrogen, which resulted in vaginal cancer later in life. Reproductive abnormalities in rodents were reported as a result of perinatal exposure to various estrogenic chemicals. Ten years later, vaginal cancers were reported in young women exposed in utero to the synthetic estrogen diethylstilbestrol (DES) and this has been called the "DES syndrome". The developing organism is particularly sensitive to developmental exposure to estrogens inducing long-term changes in various organs including the reproductive organs. The molecular mechanism underlying the persistent vaginal changes induced by perinatal estrogen exposure was partly demonstrated. Persistent phosphorylation and sustained expression of EGF-like growth factors, lead to estrogen receptor α (ESR1) activation, and then persistent vaginal epithelial cell proliferation. Agents which are weakly estrogenic by postnatal criteria may have major developmental effects, especially during a critical perinatal period. The present review outlines various studies conducted by four generations of investigators all under the influence of Prof. Bern. The studies include reports of persistent changes induced by neonatal androgen exposure, analyses of estrogen responsive genes, factors determining epithelial differentiation in the Müllerian duct, ESR and growth factor signaling, and polyovular follicles in mammals. This review is then expanded to the studies on the effects of environmental estrogens on wildlife and endocrine disruption in Daphnids.

Developmental toxicity of estrogenic chemicals on rodents and other species

Antenatal sex-hormone exposure induces lesions in mouse reproductive organs, which are similar to those in humans exposed in utero to a synthetic estrogen, diethylstilbestrol. The developing organisms including rodents, fish and amphibians are particularly sensitive to exposure to estrogenic chemicals during a critical window. Exposure to estrogens during the critical period induces long-term changes in reproductive as well as non-reproductive organs, including persistent molecular alterations. The antenatal mouse model can be utilized as an indicator of possible long-term consequences of exposure to exogenous estrogenic compounds including possible environmental endocrine disruptors. Many chemicals released into the environment potentially disrupt the endocrine system in wildlife and humans, some of which exhibit estrogenic activity by binding to the estrogen receptors. Estrogen responsive genes, therefore, need to be identified to understand the molecular basis of estrogenic actions. In order to understand molecular mechanisms of estrogenic chemicals on developing organisms, we are identifying estrogen responsive genes using cDNA microarray, quantitative RT-PCR, and differential display methods, and genes related to the estrogen-independent vaginal changes in mice induced by estrogens during the critical window. In this review, discussion of our own findings related to endocrine distuptor issue will be provided.

Multi-generational carcinogenesis from diethylstilbestrol investigated by blastocyst transfers in mice

Previous studies have shown that a carcinogenic effect can be transmitted from female mice exposed prenatally to diethylstilbestrol (DES) to their female offspring. Furthermore, male mice exposed pre-natally to DES can transmit a carcinogenic effect to their offspring through their germ cells. To study how multi-generational carcinogenesis is transmitted through females exposed pre-natally to DES, the technique of blastocyst transfer was utilized. Blastocysts from strain CD-1 mice exposed pre-natally to vehicle were transferred to mice exposed pre-natally to DES. Among 143 offspring from these transfers, there were 10 ovarian adenomas and 10 uterine adenocarcinomas. Among 92 offspring from blastocyst transfers between mice exposed pre-natally to vehicle only, there was 1 ovarian adenoma and 1 uterine adenocarcinoma. Thus the pre-natal exposure of the host to DES produced a maternal environment which increased the incidence of ovarian and uterine tumors. The reverse type of transfer was also performed, in which blastocysts from female mice exposed pre-natally to DES were transferred into mice exposed to vehicle only pre-natally. Among 99 offspring derived from DES-exposed germ cells, 6 developed ovarian adenomas and 16 developed uterine adenocarcinomas. Thus DES also has a multi-generational effect transmitted through the blastocyst, which is consistent with fetal germ cell mutation from DES.

Effects of diethylstilbestrol (DES) medication during pregnancy: report from a symposium at the 10th international congress of ISPOG

This article is a report based on presentations at the symposium Effects of Diethylstilbestrol (DES) Medication during Pregnancy at the conference Reproductive Life, 10th International Congress of The International Society of Psychosomatic Obstetrics and Gynaecology (ISPOG) in Stockholm, Sweden June 14-17, 1992. The objective of this symposium, chaired by Eylard van Hall and Ingar Palmlund, was to provide the basis for a discussion of how the risks of DES had been evaluated in different countries. In the general discussion following the presentations everybody present expressed concerns that DES might still be given to pregnant women in many parts of the world, called for measures to alert medical professionals world-wide to the hazards of the use of DES, and requested measures to effect an international ban of DES in medication for pregnant women.

Altered patterns of proteins released in vitro from oviductal and uterine tissue from adult female mice treated neonatally with diethylstilbestrol

Proteins released during incubation in vitro of oviductal and uterine tissues from 8-week-old female NMRI mice treated neonatally with diethylstilbestrol (DES) or vehicle were studied. The objective was to study if neonatal DES treatment altered the patterns of proteins released from the oviduct and uterus, as earlier studies had shown a detrimental effect of the oviductal environment in DES exposed females on early embryo development. In separate experiments nonlabeled and 35S-labeled proteins released from oviductal/uterine tissues during organ incubations were characterized with 1 and 2D gel electrophoresis. The incubation media of both oviducts and uteri from DES females had increased levels of a serum derived nonlabeled protein, identified as apolipoprotein A1. The amount of this protein in the incubation medium was not influenced by previous ovariectomy but increased by in vivo treatment with estradiol, in both ovariectomized controls and DES treated females. Three other unlabeled proteins were consistently found in higher amounts in the incubation media from DES exposed oviduct/uterine tissue, than in incubates of control tissue. In tissue incubates of oviducts from DES females, three synthesized proteins (35 kDa-pl 6.2, 112 and 143 kDa) were released in lower amounts and two in higher amounts (53 kDa-pl 6.6 and 53 kDa-pl 6.8) than in controls. In uterus from DES treated females one labeled protein was released in increased amounts (80 kDa-pl 6.7) and one in decreased amounts (43 kDa-pl 6.6), when compared with controls. In estrogen induced uterine luminal fluid from 8-week-old DES treated females the levels of four proteins (26, 42, 53 and 97 kDa) were increased and two (24 and 32 kDa) were decreased. These results show permanent alterations in levels of secreted proteins in both the oviduct and uterus of adult but neonatally DES treated females, which could be of importance for their poor reproductive performance.