Demonstration of an early abortifacient effect of norethisterone (NET) in the primate (baboon)

Teratogenicity and Reactive Oxygen Species after transient embryonic hypoxia: Experimental and clinical evidence with focus on drugs causing failed abortion in humans

Teratogenicity and Reactive Oxygen Species after transient embryonic hypoxia: Experimental and clinical evidence with focus on drugs with human abortive potential. Reactive Oxygen Species (ROS) can be harmful to embryonic tissues. The adverse embryonic effects are dependent on the severity and duration of the hypoxic event and when during organongenesis hypoxia occurs. The vascular endothelium of recently formed arteries in the embryo is highly susceptible to ROS damage. Endothelial damage results in vascular disruption, hemorrhage and maldevelopment of organs, which normally should have been supplied by the artery. ROS can also induce irregular heart rhythm in the embryo resulting in alterations in blood flow and pressure from when the tubular heart starts beating. Such alterations in blood flow and pressure during cardiogenesis can result in a variety of cardiovascular defects, for example transpositions and ventricular septal defects. One aim of this article is to review and compare the pattern of malformations produced by transient embryonic hypoxia of various origins in animal studies with malformations associated with transient embryonic hypoxia in human pregnancy due to a failed abortion process. The results show that transient hypoxia and compounds with potential to cause failed abortion in humans, such as misoprostol and hormone pregnancy tests (HPTs) like Primodos, have been associated with a similar spectrum of teratogenicity. The spectrum includes limb reduction-, cardiovascular- and central nervous system defects. The hypoxia-ROS related teratogenicity of misoprostol and HPTs, is likely to be secondary to uterine contractions and compression of uterinoplacental/embryonic vessels during organogenesis.

The baboon (Papio sp.) as a model for female reproduction studies

BIOLOGY AND REPRODUCTION

Due to their size and anatomical similarity to humans, baboons make an excellent model for reproductive studies. Baboons have a simple short cervix, muscular uterus, ovaries just lateral to the uterus and similar vasculature to that of humans. Because of the size of the animals, instruments designed for use in women can be readily used on baboons. Noninvasive determination of phase of estrous cycle is readily made by observation of changes in perineal sexual skin turgor and color.

ADVANTAGES

Some advantages of use of baboons compared to other nonhuman primates is that they are nonseasonal breeders allowing for studies to be conducted year round, have minimal infectious disease risks to humans as they do not carry Herpes B and have a social structure allowing for easy group formation. Baboons serve as good models for many conditions in humans and should be considered for studies investigating reproductive issues.

The abortifacient effect of synthetic androstane derivatives in the baboon

Synthetic androstane derivatives have been tested for their ability to induce abortion during early pregnancy in primates. Two compounds were studied following intramuscular (IM) and oral treatment in fourteen baboons. A five-day treatment regimen was started at approximately day 20 of pregnancy in 12 baboons, with treatment delayed until after day 40 in two baboons. All seven baboons treated IM with either compound aborted following intramuscular treatment, although three required a second treatment series beginning on approximately day 40 of pregnancy. Two of five baboons treated orally aborted following the single treatment series initiated around day 20 of pregnancy. The two baboons treated only after day 40 continued to term and delivered healthy infants. These compounds are therefore effective at terminating pregnancy when given around the time of the missed menstrual period. Further studies are necessary to determine optimal dose and treatment schedule.