Consequences of maternal bariatric surgery: potential for reduced amino acid availability to the fetus

Though bariatric surgery is the most effect method of durable weight loss, it is not understood why or how it works so effectively to reduce the comorbidities of Metabolic Syndrome. Both in humans and rodents, maternal bariatric surgery prior to pregnancy results in challenges during pregnancy including increased small‐for‐gestational age offspring and greater risk for fetal demise. We have shown in the rodent model of vertical sleeve gastrectomy (VSG) that offspring develop greater risk for metabolic disease later in life compared to obese controls. A common gestational cause of poor growth in utero is maternal protein deficiency. In the current work, we hypothesize that the transporters within the placenta may be differentially transporting amino acids to the fetus despite previously demonstrating that protein levels in the VSG dam were not harmed by surgery and were sufficient to sustain a health pregnancy. Using gestational day 19 placenta from pregnant Lean, Obese and post‐VSG dams, we performed analysis of the amino acid content of the placenta and prepared placental mRNA for quantitative PCR analysis of genes associated with amino acid transport. Aliphatic amino acids: isoleucine, leucine, proline and valine were significantly reduced in comparison to Lean dam levels (p< 0.05). Phenylalanine, aspartic acid and glutamic acid, arginine, histidine and methionine were also significantly reduced (p< 0.05). Furthermore, amino acid transporter SLC38A1 (SNAT1) and SLC38A4 (SNAT4) showed trends towards reductions in both VSG and Obese dams. On the contrary, SLC38A2 (SNAT2) and SLC7a7 (LAT1) was significantly elevated (p< 0.05) in VSG in comparison to Lean and Obese. This affect appeared specific to amino acids since carbohydrate transporters remained unchanged. Collectively, these data suggest that despite healthy ingestion of proteins by the VSG dam, alterations in amino acid availability to the fetus may be obstructed by the placenta after bariatric surgery. This reduced level of amino acid availability may contribute to poor outcomes in bariatric pregnancy. More work is needed to determine the relevance of these findings to humans. Support or Funding Information Research was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number P20GM104357 and P20GM121334.