Insulin-like growth factor-I expression is not increased in the retina of diabetic BB/W-rats.
A combination of immunocytochemistry, in situ hybridization and ligand binding were used to investigate the localization of IGF-I and its receptor in the retina of diabetic and non-diabetic BB/W-rats. Immunocytochemical localization revealed the presence of IGF-I in retinal pigment epithelium, ganglion cells, Muller cell processes and in microvessels. In most sites immunoreactivity was increased in the diabetic retina compared to that of non-diabetic BB/W-rats. In microvessels, however, immunoreactivity was decreased in diabetes. In situ hybridization using an antisense IGF-I riboprobe provided evidence of IGF-I synthesis in all retinal layers with a similar grain density in diabetic and non-diabetic rats. Autoradiographic localization of IGF-I receptors, using [125I]-IGF-I binding, demonstrated a diffuse localization in all retinal layers, with an increase in diabetic animals. These findings suggest that IGF-I synthesis is not altered in the diabetic retina, and that the increased immunoreactivity of IGF-I detectable in the various layers of the retina from diabetic rats may be due to an increased uptake of blood-derived IGF-I suggested by increased receptor density in diabetic rats.
Charkrabarti
S
S
Department of Pathology, University of Manitoba, Winnipeg, Canada.
Ghahary
A
A
Murphy
L J
LJ
Sima
A A
AA
D000818:Animals; D001345:Autoradiography; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics*; D007457:Iodine Radioisotopes; D008297:Male; D051381:Rats; D011913:Rats, Inbred BB; D011956:Receptors, Cell Surface / Q000032:analysis*; D017451:Receptors, Somatomedin; D012160:Retina / Q000502:physiology / Q000503:physiopathology*
D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I