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Developmental increases in glucose transporter concentration in the sheep placenta
1Department of Animal Science, Cornell University, Ithaca, New York 14853, USA.
The American Journal of Physiology
|October 10, 1997
Summary
Glucose transporter (GT) concentration increases significantly during sheep pregnancy, enhancing glucose transport capacity. The study highlights the growing importance of GLUT-3 with advancing gestation.
Area of Science:
- Reproductive biology
- Molecular physiology
- Fetal development
Background:
- Placental glucose transport is crucial for fetal growth.
- Understanding gestational changes in glucose transporters (GTs) is key to fetal well-being.
Purpose of the Study:
- To investigate the molecular mechanisms behind increased placental glucose transport capacity during sheep pregnancy.
- To quantify changes in glucose transporter (GT) expression and concentration throughout gestation.
Main Methods:
- Analysis of placental tissue from ewes at different gestational stages (days 75, 110, 140).
- Measurement of D-glucose-inhibitable binding sites using [3H]cytochalasin B.
- Quantification of GLUT-1 and GLUT-3 protein and mRNA abundance via immunoblotting and Northern blotting.
Main Results:
- Total GT concentration increased 3.4-fold from mid- to late pregnancy.
- GLUT-1 and GLUT-3 protein levels rose by 2.3- and 2.9-fold, respectively.
- GLUT-1 and GLUT-3 mRNA increased by 1.8- and 3.9-fold, respectively; GLUT-4 was undetectable.
- GLUT-1's contribution to binding sites decreased, while GLUT-3's relative importance increased with gestation.
Conclusions:
- Increased GT concentration, particularly GLUT-1 and GLUT-3, explains the enhanced placental glucose transfer capacity in late pregnancy.
- The shift towards GLUT-3 suggests its increasing role in facilitating glucose transport as gestation progresses.