Programming the offspring through altered uteroplacental hemodynamics: how maternal environment impacts uterine and umbilical blood flow in cattle, sheep and pigs.
ABSTRACT As placental growth and vascularity precedes exponential fetal growth, not only is proper establishment of the placenta important, but also a continual plasticity of placental function throughout gestation. Inadequate maternal environment, such as nutritional plane, has been documented to alter fetal organogenesis and growth, thus leading to improper postnatal growth and performance in many livestock species. The timing and duration of maternal nutritional restriction appears to influence the capillary vascularity, angiogenic profile and vascular function of the placenta in cattle and sheep. In environments where fetal growth and/or fetal organogenesis are compromised, potential therapeutics may augment placental nutrient transport capacity and improve offspring performance. Supplementation of specific nutrients, including protein, as well as hormone supplements, such as indolamines, during times of nutrient restriction may assist placental function. Current use of Doppler ultrasonography has allowed for repeated measurements of uterine and umbilical blood flow including assessment of uteroplacental hemodynamics in cattle, sheep and swine. Moreover, these variables can be monitored in conjugation with placental capacity and fetal growth at specific time points of gestation. Elucidating the consequences of inadequate maternal intake on the continual plasticity of placental function will allow us to determine the proper timing and duration for intervention.
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ABSTRACT: As a consequence of obvious ethical considerations concerning what is feasible or not in the field of human biomedical research, animal models are of critical importance both for human and veterinary medicine and cognitive scientists. Many species have been and are currently used as animal models. Rodents and lagomorphs are the most popular, essentially because of their low cost, handling and rearing facilities, limited ethical impact, and the availability of a wide range of genetic research tools in these species. Nevertheless, these models present some limitations. The physiological mechanisms observed in these species might be far from those of humans. For example, due to the large number of embryos and short gestation length, rodents and lagomorphs are not very suitable in several fields of perinatal research. Large animal species are required when surgical approaches or new medical devices have to be evaluated. The pig is widely used in these situations, as well as ruminants such as the sheep and the goat. Concerning physiological, anatomical and genetic considerations, large primates could be considered as the "gold standard" animal model because of their important similarities with humans. However, their use for biomedical research is greatly limited by their behavioral and social organization, raising important ethical questions, and their elevated cost. A very large number of experiments using ruminants as animal models have been published. A rapid bibliometric analysis performed using the Pubmed database from 1969 to 2010 retrieved 1108 literature reviews using the Mesh keywords "ruminant & animal model". Six hundred and twelve references were available only for the year 2009 using the same Mesh research and covering all types of publications. The sheep is the most widely used ruminant model, and no less than 5393 publications can be found using the Mesh keywords "sheep & animal model". The current presentation will focus on the most outstanding examples of great biomedical advances carried out with ruminant as models in the field of perinatal research. In this paper, the pivotal role of ruminants in the evaluation and development of new pharmacological treatments, new invasive procedures in fetuses, gestational imaging and genetic approaches will be developed, with their clinical context, including our own work on feto-placental imaging and the assessment of placental blood flow using quantitative 3D Doppler.Reproduction Fertility and Development 12/2011; 24(1):286. · 2.58 Impact Factor
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ABSTRACT: Animal models are of critical importance in biomedical research. Although rodents and lagomorphs are the most commonly used species, larger species are required, especially when surgical approaches or new medical devices have to be evaluated. In particular, in the field of perinatal medicine, they are critical for the evaluation of new pharmacologic treatments and the development of new invasive procedures in fetuses. In some areas, such as developmental genetics, reproductive biotechnologies and metabolic programming, the contribution of ruminants is essential. The current report focuses on some of the most outstanding examples of great biomedical advances carried out with ruminant models in the field of perinatal research. Experiments recently carried in our research unit using ruminants are also briefly described.Theriogenology 08/2012; 78(8):1763-73. · 2.08 Impact Factor