AJP - Renal Physiology, Vol 273, Issue 1 27-F37, Copyright © 1997 by American Physiological Society
Recombinant insulin-like growth factor I normalizes expression of renal glucose transporters in diabetic rats
T. Asada, T. Ogawa, M. Iwai, K. Shimomura and M. Kobayashi
Pharmacological Research Laboratories, Fujisawa Pharmaceutical, Osaka, Japan.
By immunocytochemistry we have studied the effect of recombinant human
insulin-like growth factor I (rhIGF-I) on expression of renal GLUT-1, -2,
and -5 in rats with streptozotocin (STZ)-induced diabetes. In the renal
tubules of these rats, expression of GLUT-1 was reduced and that of GLUT-2
was increased. GLUT-1 expression was restored, and GLUT-2 expression was
normalized by 2-wk administration of rhIGF-I. We have shown that GLUT-5 was
expressed at the brush-border membrane of the proximal convoluted tubules
(PCT) of the cortex and at the glomerular mesangial cells (GMC) in normal
rat kidney. In the diabetic rats, GLUT-5 expression was increased at both
sites, along with an increase of GLUT-2 expression at the basolateral
membrane of PCT, and was decreased to normal level at both sites by
treatment with rhIGF-I. Thus, like GLUT-2, GLUT-5 is suggested to regulate
glucose reabsorption in PCT. The relationship between overexpression of
GLUT-5 in GMC and accumulation of sorbitol and advanced glycosylation end
products are discussed. Regulation of GLUT expression may play an important
role on renal glucose homeostasis.
