Ga. Badr et al., Glut1 and Glut3 expression, but not capillary density, is increased by cobalt chloride in rat cerebrum and retina, MOL BRAIN R, 64(1), 1999, pp. 24-33
Treatment of rats with cobalt chloride [Co(LI)], an agent that stimulates t
he expression of a set of hypoxia-responsive genes, for 10-12 days resulted
in 1.45- and 1.40-fold increases in the content of Glut1 mRNA and Glut1 in
cerebral gray matter, respectively (P < 0.05 for both changes). The increa
se in Glut1 content was associated with a significant increase in the conte
nt of Glut1 staining in microvessels isolated from cerebral gray matter, an
d in the intensity of Glut1 in microvessels of the frontal lobe and hippoca
mpus assessed by immunohistochemistry. The abundance of Glut3 in cerebrum o
f Co(II)-treated rats also increased by 1.3-fold(P < 0.05), but the increas
e was not associated with a change in the content of Glut3 mRNA. In retina,
treatment with Co(II) resulted in 2.48- and 1.23-fold increases in the con
tent of Glut1 mRNA and Glut1 protein, respectively (P < 0.05 for both chang
es); similar increases in Glut1 protein expression were observed in isolate
d retinal microvasculature. The content of Glut3 in retina also increased 1
.5-fold in Co(II)-treated rats (P < 0.05). In addition, treatment with Co(I
I) resulted in a significant 2.2-fold increase in the expression of VEGF in
the cerebrum. However, despite the Co(II)-induced increase in Glut1 expres
sion in cerebral and retinal microvasculature and VEGF in cerebrum, there w
as no increase in the capillary density in either tissue. It is concluded t
hat a 10-12 day exposure to Co(II), presumably acting through the hypoxia-s
ignaling pathway, results in enhanced expression of both major glucose tran
sporters in cerebral cortex and retina, without increasing the capillary de
nsity of either tissue. (C) 1999 Elsevier Science B.V. All rights reserved.