Effects of maternal undernutrition on the growth, development and antioxidant status of ovine placentome subtypes during late pregnancy

Abstract

This study investigated the effects of maternal undernutrition on the growth, development and antioxidant status of ovine placentome subtypes during late pregnancy. Eighteen time-mated Mongolian ewes with singleton fetuses were allocated to three groups at d 90 of pregnancy: Restricted Group 1 (RG1, 0.18 MJ ME · kg BW−0.75 · d−1, n = 6), Restricted Group 2 (RG2, 0.33 MJ ME · kg BW−0.75 · d−1, n = 6) and Control Group (CG, ad libitum, 0.67 MJ ME · kg BW −0.75 · d −1, n = 6). All animals were supplied chopped hay during the restriction period. At 140 days of pregnancy, the gravid uterus was removed; then individual fetuses and placentae were weighed. The numbers and weight of the placentome subtypes were examined. The number of vessels of the placentome subtypes were observed in sections stained with hematoxylin-eosin. The indexes of antioxidant capacity and oxidative stress, including total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and mal-ondialdehyde (MDA) concentration, were measured by spectrometric kits. The fetal weights, placental weights and the numbers of Type A placentomes in both restricted groups were reduced (P < .05). Decreased fetal/placental weight ratio and increased total weight of the Type A placentome were found in the RG1 group compared to CG (P < .05). The total weights and the numbers of the Type B, Type C and Type D increased with severe maternal undernutrition in RG1 compared to CG (P < .05), as well as the increased numbers of Type B in the RG2 group compared to the CG group (P < .05). The placentome subtypes in RG1, including Type A, Type B and Type C, exhibited decreased concentrations of T-AOC and SOD activities, but higher MDA concentration and GSH-Px activity than those in CG (P < .05). For the RG2 group, the decreased T-AOC and SOD and increased GSH-Px were found in Type A placentome compared to CG (P < .05). For the same subtype placentome, there were no differences in the number of vessels among CG, RG2 and RG1 (P > .05); however, the number of vessels and MDA concentration of Type C and Type D placentome were higher than those of the Type A and Type B (P < .05). These results indicate that the growth and development of ovine Type A placentome was altered during late pregnancy. More and more Type B, Type C and Type D were formed from the Type A associated with maternal undernutrition. Oxidative stress occurred in all types of placentomes for the RG1 group, and the more flattening placentomes that were converted, the worse the antioxidant/pro-oxidant imbalance that was induced.