Reduced fetal vitamin D status by maternal undernutrition during discrete gestational windows in sheep

Abstract

Placental transport of vitamin D and other nutrients (e.g. amino acids, fats and glucose) to the fetus is sensitive to maternal and fetal nutritional cues. We studied the effect of maternal calorific restriction on fetal vitamin D status and the placental expression of genes for nutrient transport [aromatic T-type amino acid transporter-1 (TAT-1); triglyceride hydrolase/lipoprotein uptake facilitator lipoprotein lipase (LPL)] and vitamin D homeostasis [CYP27B1; vitamin D receptor (VDR)], and their association with markers of fetal cardiovascular function and skeletal muscle growth. Pregnant sheep received 100% total metabolizable energy (ME) requirements (control), 40% total ME requirements peri-implantation [PI40, 1-31 days of gestation (dGA)] or 50% total ME requirements in late gestation (L, 104-127 dGA). Fetal, but not maternal, plasma 25-hydroxy-vitamin D (25OHD) concentration was lower in PI40 and L maternal undernutrition groups (P < 0.01) compared with the control group at 0.86 gestation. PI40 group placental CYP27B1 messenger RNA (mRNA) levels were increased (P < 0.05) compared with the control group. Across all groups, higher fetal plasma 25OHD concentration was associated with higher skeletal muscle myofibre and capillary density (P < 0.05). In the placenta, higher VDR mRNA levels were associated with higher TAT-1 (P < 0.05) and LPL (P < 0.01) mRNA levels. In the PI40 maternal undernutrition group only, reduced fetal plasma 25OHD concentration may be mediated in part by altered placental CYP27B1. The association between placental mRNA levels of VDR and nutrient transport genes suggests a way in which the placenta may integrate nutritional cues in the face of maternal dietary challenges and alter fetal physiology.

Investigation of relationship between vitamin D status and reproductive fitness in Scottish hill sheep

“…However, in the last 2 decades, numerous studies have reported that vitamin D deficiency is associated with many non-skeletal health problems, such as autoimmune diseases, hypertension and cancer 9,10 . The presence of vitamin Dreceptors in the reproductive tract of women 11 and females of other species, such as sheep 12 , goat 13 , mouse 14,15 and rat 16 , and in ovine male reproductive tracts 17,18 indicates that vitamin D may influence reproductive performance. Several human studies have found that vitamin D deficiency before and during pregnancy is associated with reduced reproductive success and increased risk of the newborn being small for gestational age, lighter in weight at birth, or having reduced head circumference 19–22 .…”