Low Expression of FGF23 and Its Effect on Rats with Intrauterine Growth Retardation

Objective::To explore the levels of fibroblast growth factor 23 (FGF23) during pregnancy and its relationship with intrauterine growth restriction (IUGR).Methods::Pregnant rats were classified into an ad libitum rat chow group (ad libitum rat chow, AD group, n = 25) and an undernutrition group (50% of their daily food requirement, UN group, n= 25). The levels of maternal serum FGF23, tissue homogenate FGF23, and bone gla protein in fetal rats, and placental FGF23 mRNA and protein expression were examined by enzyme-linked immunosorbent assay, real-time qPCR analysis respectively. Finally, the effect of recombinant FGF23 on the viability of MG-63 cells was determined by cell proliferation assay. Data were analyzed with independent two-tailed t test and one-way analysis of variance. Spearman rank-order correlation coefficients (continuous variables) was performed to determine the relationship of results. Results::The diet restriction induced IUGR in rat offsprings, and the UN group exhibited a significantly lower FGF23 level ( P < 0.05, n= 5). The FGF23 level was increased and peaked in maternal serum on gestation day (GD) 15, but peaked in fetal and placenta on GD20. Moreover, the tissue homogenate levels of FGF23 and bone gla protein in fetal rats in both groups were positively correlated ( r= 0.923, P < 0.05; r= 0.925, P < 0.05, respectively, n = 15), FGF23 was localized to both decidual and labyrinth zones, with remarkably higher expression on GD20, P < 0.05, n= 5. In vitro, recombinant human FGF23 enhanced MG-63 cell viability, P < 0.05, n= 5. Conclusion::Prenatal undernutrition could decrease the FGF23 expression in fetal rats caused by the mother through the placenta, and induced the IUGR and hindered the ossification. And the FGF23 levels are peaked on GD15 mother but peaked on GD20 placenta and fetuses, these might be associated with the over compensation of maternal placenta on GD20.