Assisted reproductive technology causes reduced expression of amino acid transporters in human full-term placentas

In the mouse model, manipulations of assisted reproductive technology (ART) can lead to enlarged placentas and influence the expression of amino acid transporters in placentas during mid-to late-gestation. However, it is uncertain whether those abnormal changes presented in ART mouse placentas also occur in human ART placentas.

We choose the placenta tissue of pregnant woman by ART in term birth (ART group) and by natural pregnancy in term birth (control group) to compare the birth weight of the baby, placental weight and ratio of the fetal/placental weight of these two groups. We then detect the mRNA and protein expression of placental amino acid transporter genes (SNAT1, SNAT2, SNAT4, LAT1 and LAT2) in these two groups by real-time quantitative PCR, Western blot and immunofluorescence staining. Additionally, the PI3K-AKT-mTOR signaling activity was also analyzed.

There were no statistical differences in new birth weight between the ART group and the control group. Compared with the control group, the placenta weight of baby was significantly higher in ART group and ratio of the fetal/placental weight was significantly lower in ART group. We found that the mRNA and protein expression of A system of amino acid transporter SNAT1, SNAT2 and SNAT4 in placenta were significantly down-regulated in ART group compared with placentas from natural pregnancies. Additionally, there were no statistical differences of the mRNA and protein expression of L system of amino acid transporter LAT1 between these two groups, but amino acid transporter LAT2 in placenta was significantly down-regulated in ART group. Furthermore, the PI3K-AKT-mTOR signaling activity was inhibited in ART group.

ART leads to the expressions of amino acid transporter genes SNAT1, SNAT2, SNAT4 and LAT2 significantly down-regulated in placenta accompanied by the PI3K-AKT-mTOR signaling inhibition, which suggests that ART may affect the function of placenta amino acid transporter during the late pregnancy, leading to enlarged placentas and probably low birth weight.