AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 6 1488-R1495, Copyright © 1994 by American Physiological Society
GLUT3 glucose transporter isoform in rat testis: localization, effect of diabetes mellitus, and comparison to human testis
C. F. Burant and N. O. Davidson
Department of Medicine, University of Chicago, Illinois 60637.
Facilitative hexose transporter expression was compared in rat and human
testes. In rat testis, only GLUT1 and GLUT3 proteins were expressed. By
contrast, human testis expressed GLUT1 and GLUT3 in addition to GLUT5.
Immunocytochemical studies showed that GLUT3 was expressed in all cells of
the seminiferous epithelium of rat testis, including sperm. In human
testis, GLUT3 was expressed exclusively in cells juxtaposed to the lumen of
the seminiferous tubule and ejaculate sperm, a pattern of expression that
was identical to that of GLUT5. Induction of insulinopenic diabetes
mellitus in the rat did not alter the levels or the distribution of GLUT3
protein or mRNA in the testis. Moreover insulin treatment of the diabetic
rats did not produce changes in GLUT3 mRNA or protein levels. The results
show that rat and human testis express the high-affinity glucose
transporter GLUT3, which allows for the efficient uptake of glucose. In
addition, the testis may be protected from changes in glucose transporter
expression in experimental diabetes.
