Decidualization and implantation: embryo-uterine bioinformatics at work

Adiponectin and its receptors in preimplantation embryo development

Adiponectin can play an important role in regulating the female reproductive function and embryo development and can affect the embryo at very early stages of pregnancy--during the preimplantation period. Disturbances in the maternal adiponectin system are associated with several diseases, including diabetes type 2, obesity, and some female reproductive disorders. Adiponectin receptors are expressed in oocytes and preimplantation embryos and can be activated by adiponectin produced by maternal adipose tissue or organs of the female reproductive tract. Adiponectin can affect proliferation and survival of cells in preimplantation embryos, and these effects are isoform dependent. Experimental results suggest involvement of various protein kinases, including mitogen-activated protein kinases, in the regulation of these processes by adiponectin. Actions of adiponectin on lipid and glucose metabolism can increase the energy supply to the embryo, and final targets of adiponectin signaling are metabolic enzymes, glucose transporters, and fatty acid transporters. The involvement of several signaling molecules, such as AMPK/PRKA, PI3K, or AKT/PKB, in the regulation of metabolic processes by adiponectin has been demonstrated in preimplantation embryos. In summary, adiponectin produced in an endocrine/paracrine/autocrine manner can significantly influence preimplantation embryo development, uterine receptivity, and embryo implantation.

Kinetics of bromhexine-mediated down-regulation of focal adhesive molecules of uterus and trophectoderm affecting conception in the rat

PURPOSE

Quantitative evaluation of properties of bromhexine (B) for expression of uterine proteins in ovariectomized (OVX) and pregnant rats.

MATERIALS AND METHODS

Expression of proteins through SDS-PAGE, along with incorporation of glycosidic moieties, was conducted in pregnant and OVX rats under B influence. These findings were corroborated with other tests such as implantation sites, fetal and litter sizes in pregnant rats.

RESULTS

In OVX animals, even under the influence of estradiol dipropionate and progesterone, the B recreated a condition akin to OVX animals. It also induced 50-80% inhibition in the incorporation of glycosidic moieties to polypeptide chain. Distinct reduction in implantation sites, fetal sizes and interference in the conception (16/46) in pregnant rats substantiated the results of the action of B as an antiimplantation agent.

CONCLUSION

Bromhexine has shown interference in blastocyst attachment, conception, reduction in number of implantation sites and dwarfing of fetuses; hence, it is a potential candidate for antiimplantation.

A model for implantation: coculture of blastocysts and uterine endometrium in mice

One of the limitations in embryo implantation research is the lack of an available in vitro model that faithfully replicates embryo-uterine interactions. In previous studies, embryos were cultured on a monolayer of either uterine epithelial cells or extracellular matrix substratum on which embryos could adhere and outgrow. However, these models failed to display embryonic invasion, primarily because of the shortage of critical structural and molecular supports that are available in vivo. In the present study, we used intact mouse uterine endometrium collected on Day 4 of pregnancy and placed in contact with blastocysts to initiate coculture experiments in a defined medium at the air-liquid interface. The culture medium was composed of Ham F-12/Dulbecco modified Eagle medium (1:1), 30% fetal calf serum, 63.5 nmol/L of progesterone, 7.14 nmol/L of estradiol-17beta, 100 mug/ml of insulin, and 20 ng/ml of epidermal growth factor, whereas the incubation condition was mixed air of 50% oxygen, 5% carbon dioxide, and 45% nitrogen with a humidity of greater than 90% at 37 degrees C. Our observations from 24 h of culture clearly demonstrated that embryos were capable of attachment to the uterine endometrium and displayed partial invasion into the endometrial stroma. Interestingly, no outgrowth of trophoblasts on the surface of uterine endometrium was seen, but embryos exhibited a pole-specific attachment. Overall, this model is capable of demonstrating a true invasion of embryo within the endometrial stroma and may be suitable in studies related to early embryo implantation.