Implications of Intermittent Fasting on Placental Function

Introduction: Women who partake in Ramadan during pregnancy have lower placental weights. Intermittent fasting (IF) impacts upon asynchronous dietary cues and the entrained sleep cycle. The effects of IF on placental development and function have not been studied. Amino acid and calcium transport are key markers of a placentas nutrient transporting capabilities and are measured in pathological pregnancies to evaluate placental function.
Hypothesis: IF alters regulation of nutrient transporters in the placenta which may impact fetal wellbeing. These transporters may be under direct circadian control.
Methods: Rats were used to model either control or IF diet regimes during pregnancy. At term, fetal and placental weights were recorded and placental tissues homogenised. BeWo, a trophoblast-derived cell line, were cultured in different glucose concentrations to mimic asynchronous dietary cues. For both models protein content of key amino acid and calcium nutrient transporters (SNAT2, TRPV6, PMCA and Calbindin-D9K) and circadian machinery proteins (CLOCK and BMAL1) were quantified by western blotting. Analysis determined localisation and expression in response to dietary cues.
Results: Rat placental weight was reduced and fetal weight increased in IF versus control diets. Placental protein expression of TRPV6 and PMCA and SNAT2 was decreased whereas CLOCK protein was increased. In BeWo, both CLOCK and BMAL1 were localised to the nucleus and cytoplasm. Asynchronous dietary cues manipulate the expression of CLOCK and BMAL1 in BeWo. Serum shocking did not stimulate circadian oscillations in BeWo, but reduced CLOCK expression.
Discussion: The IF rat model mimicked effects on placental weight seen in humans during Ramadan. This coincided with aberrant nutrient transporter expression and circadian disruption. Placental reserve capacity may account for discrepancies in placental size and fetal weight seen in this model. Both models suggest that circadian machinery exists in placental trophoblasts. Transporter activity during circadian disruption should be investigated to reveal the effect of IF during pregnancy on placental function and fetal outcome.