Abstract
Offspring adrenal function may be negatively affected in utero by maternal stressors such as microbial infection. Maternal supplementation with immunomodulatory compounds such as omega-3 polyunsaturated fatty acids (n-3 PUFA) may help minimize the adverse effects of maternal stress on fetal hypothalamic-pituitary-adrenal development and improve offspring health. Presently, n-3 PUFA sources are primarily fish-based, but n-3 PUFA microalgae (AL) may be an alternative. Previously, it was determined that maternal AL or fish oil (FO) supplementation to sows, in addition to maternal stress induced by Escherichia coli lipopolysaccharide (LPS) challenge appeared to have a greater influence on the stress response of male offspring compared to females. To further elaborate on these findings, this study assessed the effects of maternal AL or FO supplementation combined with a maternal LPS challenge on adrenal gene expression in male offspring fed a nursery diet containing low-quality protein sources. Forty-eight sows were fed gestation diets starting on gestation day (gd) 75 containing either 3.12% AL, 3.1% FO, or a control diet containing 1.89% corn oil. On gd 112, half the sows in each treatment were administered 10 μg/kg LPS i.m. Piglets were weaned at 21 days of age onto a common low-quality plant-based protein diet, and one week after weaning, four piglets per sow were administered 40 μg/kg LPS i.m. Two hours later, the piglets were euthanized to obtain adrenal tissue, and total RNA was extracted to carry out transcriptome analysis using the Affymetrix GeneChip WT Plus assay and subsequent validation by real-time PCR. Analysis revealed that adrenal steroidogenesis, fatty acid metabolism and immune function were significantly influenced by maternal diet and stress. Increased expression of immune-related genes including lymphocyte antigen 96, TLR-2 and NF-κB suggests that maternal AL supplementation may increase offspring sensitivity to inflammation after weaning. Decreased expression of lymphocyte antigen 96 in male offspring from sows receiving maternal LPS challenge also suggests a possible role of maternal stress in diminishing the offspring immune response to immune stress challenge. Increased expression of the genes encoding the 11BHSD2 enzyme in offspring from sows fed FO may also reduce the magnitude of the stress response. These data provide insight to the immune and metabolic mechanisms that may be influenced by maternal diet and stress.