Impact of periconceptional undernutrition in the sheep on maternal and fetal leptin in singleton and twin pregnancies during late gestation

Abstract

[Objective/]: Leptin is predominantly synthesised and secreted by adipocytes and plays a key role in the regulation of energy homeostasis. In the Dutch Winter Hunger Famine Study, the rate of obesity was higher in 19 year old men whose mothers had been exposed to the famine during the first half of pregnancy. There have been no studies, however, of the impact of maternal undernutrition specifically during the early periconceptional period or during the period of fetal fat deposition, on fetal adiposity or on fetal plasma leptin concentrations. We have therefore investigated the effects of exposure of the embryo and fetus to maternal undernutrition during either the periconceptional period (from 0-7 d gestation) or during the gestational period (from 8 - 140 d gestation) on fetal fat deposition and maternal and fetal plasma concentrations of leptin throughout late gestation. [Methods/]: Forty five ewes were assigned to one of two feeding regimes at 60d before mating- Control (C, n = 20) or Restricted (R, n = 25) (70% of the control allowance). At 7 d alter mating, ewes were then assigned to a C or R group. There were thus 4 treatment groups: C-C (n = 12), CR, (n = 8), R-R (n = 14) and R-C (n = 11). Vascular catheters were inserted at 105-11Od gestation and blood samples were collected for the measurement of leptin by ELISA. The effects of nutrition on plasma leptin concentrations were compared separately in singleton and twins using a multifactorial ANOVA with repeated measures. [Results/]: There was no effect of either restricted periconceptional or gestational nutrition on maternal or fetal plasma leptin concentrations in singleton or twin pregnancies during late gestation. In ewes carrying twins, maternal plasma leptin concentrations after 135d in were directly related to the change in ewe weight experienced during the prepregnancy period (maternal leptin = 0.9 (change in ewe weight) + 7.8; r= 0.6, P < 0.05) In twins, there was also a significant relationship between maternal and fetal leptin (maternal leptin = 0.5 fetal leptin + 4.2, r=0-63, P < 0.005). The relative mass of fetal perirenal fat was significantly higher in twin fetuses in the C-R group when compared to the other nutritional treatment groups. [Conclusion/]: The impact of changes in maternal nutrition before and throughout pregnancy are dependent on fetal number. A decrease in prepregnancy weight resulted in a decrease in maternal leptin concentrations in late gestation in ewes carrying twins, but not singletons. Whilst fetal adiposity is altered by restricted gestational nutrition in twins, this was not associated with changes in circulating fetal leptin.