[Frontiers in Bioscience E4, 1434-1450, January 1, 2012]

Maternal protein restriction regulates IGF2 system in placental labyrinth

Haijun Gao1, Kunju Reddiar Sathishkumar1, Uma Yallampalli1, Meena Balakrishnan1, Xilong Li2, Guoyao Wu2, Chandra Yallampalli1

1Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX , 2Department of Animal Science, University of Texas A&M University, College Station, TX

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Materials and methods
3.1. Animals
3.2. DNA extraction from fetal extraembryonic membrane and sex determination
3.3. Annotation of rat IGF2P0 transcript for primer design
3.4. RNA extraction and RT-PCR
3.5. Quantitative real-time PCR
3.6. Western blotting
3.7. Analysis of amino acids in maternal plasma
3.8. Statistical analysis
4. Results
4.1. Gender determination of placenta and fetus
4.2. Feto-placental weights affected by Day of pregnancy, Diet and Gender of fetus and placenta
4.3. Expression of Igf2 and placental specific transcript Igf2P0 in labyrinth zone in response to maternal protein restriction
4.4. Expression of Igf2 receptors in labyrinth zone in response to maternal protein restriction
4.5. Expression of Igfbp1 and Igfbp2 in labyrinth zone in response to maternal protein restriction
4.6. Amino acids in maternal plasma
5. Discussion
6. Acknowledgement
7. References

1. ABSTRACT

This study was to test the hypothesis that altered IGF2 system in the placental labyrinth zone (LZ) impairs feto-placental growth in response to maternal protein restriction. Rats were fed a 20% protein diet and an isocaloric 6% protein diet (LP) from day 1 to days 14, 18, or 21 of pregnancy. The effects of diet, gender of placenta and fetus, and day of pregnancy on placental weight, fetal weight, and expression of the IGF2 axis in the placental LZ and amino acids in maternal plasma were analyzed. Growth restriction occurred in both female and male fetuses by LP, coincident with impaired LZ growth and efficiency. The expression of Igf2, Igf2P0, Igf1r, Igf2r, Insr, Igfbp1, and Igfbp2 in placental LZ were affected by diet, gender and/or day of pregnancy. Concentrations of total essential amino acids and total nonessential amino acids were reduced and increased, respectively, in maternal plasma of LP-fed rats. These results indicate that adaptation of the IGF2 system in rat LZ occurs in a sex- and time-dependent manner in response to maternal protein restriction; however, these adaptations cannot prevent the growth restriction of both male and female fetuses during late pregnancy.