Proceedings of The Physiological Society
University College London (2011) Proc Physiol Soc 24, PC22
Intermittent fasting reduces placental Ca2+-ATPase expression in the rat
L. Sansby1, S. H. Alwasel2, N. Ashton3, H. Bond1
1. School of Applied Science, University of Huddersfield, Huddersfield, Yorkshire, United Kingdom. 2. College of Science, King Saud University, Riyadh, Saudi Arabia. 3. School of Life Sciences, University of Manchester, Manchester, United Kingdom.
During mammalian gestation the fetus is dependent upon the placenta for the transfer of maternal nutrients. In humans placental growth responds to maternal influences such as diet and physical activity. While the effects of dieting on placental development and function have been studied widely, the effects of intermittent fasting have not. During the month of Ramadan Muslims refrain from eating and drinking during the hours of daylight. Although pregnant women are exempt from the fast many participate. In a recent human study conducted in Saudi Arabia we showed that babies who were in the second or third trimester of gestation when their mothers fasted had lower mean placental weights and placental weight to birth weight ratios compared with those not in utero during Ramadan . We observed similar changes in placental and body weights in rats whose mothers were subject to intermittent fasting (IF) during pregnancy . Approximately 80% of the calcium forming the fetal skeleton is transported across the placenta from the mother by the end of gestation. Disruptions to calcium homeostasis during gestation can lead to an increased risk of developing osteoporosis in later life . Calcium transport across placental epithelium occurs in 3 stages: diffusion into the trophoblast from maternal plasma through epithelial Ca2+ channels of the transient receptor potential (TRP) gene family, transfer across the trophoblast cytoplasm bound to the calcium binding protein calbindin-D9K and lastly active extrusion into the fetal compartment via the plasma membrane Ca2+-ATPase (PMCA) localised to the fetal facing basal plasma membrane . The aim of this study was to determine whether maternal IF alters active placental Ca2+ transport. Control pregnant Wistar rats had access to food ad libitum (C n=6); in rats subject to intermittent fasting food was withdrawn at 17.00 and returned at 09.00 daily from day 1 of pregnancy until birth; food was available ad libitum for the remainder of the day (e.g. from 09.00 to 17.00) (IF n=6). All rats had free access to water throughout. Placental tissue was harvested at embryonic day 21 and PMCA expression determined by Western blot. PMCA expression in IF placentas was significantly lower compared with that in controls (P<0.05, Mann-Whitney test, Figure 1). These data suggest that fetal Ca2+ accretion is diminished in the later stages of gestation exposed to intermittent fasting.
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