ABUNDANT EXPRESSION OF GLUT1 AND GLUT3 IN RAT EMBRYO DURING THE EARLYORGANOGENESIS PERIOD

The developmental change of both GLUT1 and GLUT3 protein in rat embryo nal and fetal brain was examined using Western blot analysis and immun ohistochemistry. The brains were collected from fetuses (gestational d ays 10 to 20), newborn, and adult rats. On day 10, the levels of GLUT1 and GLUT3 expressions were twofold higher than those of adult levels, but thereafter decreased rapidly as the gestation progressed. The tis sue distribution of GLUT1 and GLUT3 in embryo was apparently distinct. On day 10, GLUT1 was expressed in the neural tube, gut, heart and opt ic vesicle, while GLUT3 was expressed in the surface ectoderm and gut. Thus, high affinity glucose transporters may be required in the early organogenesis period because their energy requirement is completely d ependent upon anaerobic glycolysis. GLUT3 may facilitate glucose trans fer from amniotic fluid to the embryo and GLUT1 may supply glucose for use as an embryonal fuel. (C) 1995 Academic Press, Inc.