Animal Models of Fetal Medicine and Obstetrics

Animal models remain essential to understand the fundamental mechanisms occurring in fetal medicine and obstetric diseases, such as intrauterine growth restriction, preeclampsia and gestational diabetes. These vary regarding the employed method used for induction of the disease, and differ in relation to the animal characteristics (size, number of fetuses, placenta barrier type, etc.). While none of these exactly mirrors the human condition, different pregnant animal models (mice, rats, guinea pigs, chinchillas, rabbits, sheep and pigs) are here described with respect to advantages and limitations. The ability to employ noninvasively diagnostics varies among species, specifically for ultrasound and clinical magnetic resonance imaging procedures. Management of feeding, handling, care and anesthesia are particularly important factors in the pregnant animal

Transplacental Transport of Artificial Sweeteners

The prevalence of obesity is increasing, and the origins of obesity and metabolic dysfunction may be traced back to fetal life. Currently, overweight pregnant women are advised to substitute sugar-sweetened beverages with diet drinks containing artificial sweeteners. Recent evidence suggests that the consumption of artificial sweeteners during pregnancy increases the risk of obesity in the child, but the mechanism is unknown. We hypothesized the transportation of artificial sweeteners across the placenta into the fetal circulation and the amniotic fluid. We included 19 pregnant women who were given an oral dose of acesulfame, cyclamate, saccharin, and sucralose immediately before a planned caesarean section. Nine women were included as controls, and they refrained from an intake of artificial sweeteners. The maternal and fetal blood and amniotic fluid were collected during the caesarean section, and concentrations of artificial sweeteners were measured using mass spectrometry. We found a linear relationship between the fetal plasma concentrations of artificial sweeteners and the maternal plasma concentrations, with adjusted coefficients of 0.49 (95% CI: 0.28–0.70) for acesulfame, 0.72 (95% CI: 0.48–0.95) for cyclamate, 0.51 (95% CI: 0.38–0.67) for saccharin, and 0.44 (95% CI: 0.33–0.55) for sucralose. We found no linear relationship between amniotic fluid and fetal plasma concentrations, but there were positive ratios for all four sweeteners. In conclusion, the four sweeteners investigated all crossed the placenta and were present in the fetal circulation and amniotic fluid

Biodistribution of [11C]-Metformin and mRNA Expression of Placentae Metformin Transporters in the Pregnant Chinchilla

Background. While metformin is the first-line pharmacological treatment of diabetes mellitus type 2, this drug is not considered safe to use in pregnant women because of its unknown consequences for the fetus. In this study, we aimed to investigate the biodistribution of metformin in the pregnant chinchilla, a species exhibiting placental characteristics comparable with the pregnant woman. Furthermore, we aimed to investigate the expression of metformin transporters in humans and chinchillas, respectively, in order to evaluate the pregnant chinchilla as a novel animal model for the use of metformin in pregnancy. Methods. Three chinchillas in the last part of gestation were injected with [11C]-metformin and scanned by PET/CT for 70 minutes to visualize the distribution. To investigate the difference in expression of placenta transporters between humans and chinchillas, PCR was performed on samples from five chinchilla placentae and seven human placentae. Results. Dynamic PET with [11C]-metformin showed that the metformin distribution in chinchillas was similar to that in nonpregnant humans, with signal from kidneys, liver, bladder, and submandibular glands. Conversely, no radioactive signal was observed from the fetuses, and no metformin was accumulated in the chinchilla fetus when measuring the SUV. PCR of placental mRNA showed that the human placentae expressed OCT3, whereas the chinchilla placentae expressed OCT1. Conclusion. Since metformin did not pass the placenta barrier in the pregnant chinchilla, as it is known to do in humans, we do not suggest the chinchilla as a future animal model of metformin in pregnancies