Maternal serum omentin-1 profile is similar in humans and in the rat animal model

Omentin-1 is an adipocytokine with anti-inflammatory activity that has been associated with different metabolic disorders. The aim of this study is to investigate the serum profiles of omentin-1 throughout human and rat pregnancy. Serum omentin-1 levels were determined by ELISA in a prospective cohort study of healthy pregnant women (n=40) during the three trimesters of pregnancy and in twenty healthy non-pregnant women during the follicular and luteal phase of the menstrual cycle. In addition, serum omentin-1 levels were measured in rats during different periods of pregnancy (gestational days 8, 12, 16, 19, and 21) and in an age-matched control (virgin) group of rats (n=12rats/group). Finally, immunohistochemistry was used to demonstrate the presence of omentin-1 protein in human and rat placenta. Omentin-1 immunoreactivity was detected in cytotrophoblasts, syncytiotrophoblasts, sparse Hofbauer cells, and endothelial cells of the stem villi of human placenta. Additionally, it was detected in the labyrinthine trophoblast and yolk sac layer of the rat placenta. Human and rat serum omentin-1 levels were significantly lower in the late gestational period when compared with the non-pregnant women and virgin rats (p<0.05). Serum omentin-1 changes were not significant throughout the gestation in both species (p>0.05). Human serum omentin-1 levels have an inverse relationship with triglyceride levels during pregnancy. Our findings have not determined the exact role of omentin-1 during pregnancy, concerning the metabolic control of triglycerides and other energy sources. Whether omentin-1 decrease implies a regulatory function is still not clear. Further studies are needed to address this issue and determine the role of omentin-1 in metabolic adaptations during normal human and rat pregnancy.