§The current address of Xilong Li is Institute of Feed Research, The Chinese Academy of Agricultural Sciences, 100081 Beijing, China.
The current address of Huaijun Zhou is Department of Animal Science, University of California at Davis, Davis, CA 95616, USA.
Academic Editor: Graham Pawelec
Background: Increasing the dietary provision of L-arginine to pregnant swine beginning at Day 14 of gestation enhances embryonic survival, but the underlying mechanisms are largely unknown. Objective: This study determined the effects of dietary supplementation with 0.8% L-arginine to gilts between Days 14 and 25 of gestation on the global expression of genes in their placentae. Methods: Between Days 14 and 24 of gestation, gilts were fed 2 kg of a corn- and soybean meal-based diet (containing 12.0% crude protein and 0.70% Arg) supplemented with 0.8% L-arginine or without L-arginine (0.0%; with 1.64% L-alanine as the isonitrogenous control). On Day 25 of gestation, 30 min after the consumption of their top dressing containing 8 g L-arginine or 16.4 g L-alanine, gilts underwent hysterectomy to obtain placentae, which were snap-frozen in liquid nitrogen. Total RNAs were extracted from the frozen tissues and used for microarray analysis based on the 44-K Agilent porcine gene platform. Results: L-Arginine supplementation affected placental expression of 575 genes, with 146 genes being up-regulated and 429 genes being down-regulated. These differentially expressed genes play important roles in nutrient metabolism, polyamine production, protein synthesis, proteolysis, angiogenesis, immune development, anti-oxidative responses, and adhesion force between the chorioallantoic membrane and the endometrial epithelium, as well as functions of insulin, transforming growth factor beta, and Notch signaling pathways. Conclusion: Dietary supplementation with L-arginine plays an important role in regulating placental gene expression in gilts. Our findings help to elucidate mechanisms responsible for the beneficial effect of L-arginine in improving placental growth and embryonic/fetal survival in swine.