Short-term insulin treatment and aortic expressions of IGF-1 receptor and VEGF mRNA in diabetic rats.
We investigated the relationship between the changes in vascular responsiveness and growth factor mRNA expressions induced by 1-wk treatment with high-dose insulin in control and established streptozotocin (STZ)-induced diabetes. Aortas from diabetic rats, but not those from insulin-treated diabetic rats, showed impaired endothelium-dependent relaxation in response to ACh (vs. untreated controls). The ACh-induced nitrite plus nitrate (NOx) level showed no significant difference between controls and diabetics. Insulin treatment increased NOx only in diabetics. In diabetics, insulin treatment significantly increased the aortic expressions of endothelial nitric oxide synthase (eNOS) mRNA and VEGF mRNA. The expression of IGF-1 mRNA was unaffected by diabetes or by insulin treatment. In contrast, the mRNA for the aortic IGF-1 receptor was increased in diabetics and further increased in insulin-treated diabetics. In aortic strips from age-matched control rats, IGF-1 caused a concentration-dependent relaxation. This relaxation was significantly stronger in strips from STZ-induced diabetic rats. These results suggest that in STZ-diabetic rats, short-term insulin treatment can ameliorate endothelial dysfunction by inducing overexpression of eNOS and/or VEGF mRNAs possibly via IGF-1 receptors. These receptors were increased in diabetes, perhaps as result of insulin deficiency.
Kobayashi
Tsuneo
T
Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
Kamata
Katsuo
K
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000503:physiopathology; D001786:Blood Glucose; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000503:physiopathology; D016228:Endothelial Growth Factors / Q000235:genetics*; D004730:Endothelium, Vascular / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000097:blood / Q000494:pharmacology*; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008222:Lymphokines / Q000235:genetics*; D008297:Male; D009566:Nitrates / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics; D052250:Nitric Oxide Synthase Type III; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D017526:Receptor, IGF Type 1 / Q000235:genetics*; D040262:Receptors, Vascular Endothelial Growth Factor / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D001786:Blood Glucose; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D007004:Hypoglycemic Agents; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D009566:Nitrates; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014665:Vasodilator Agents; D009599:Nitroprusside; D019335:Nitroarginine; D007334:Insulin-Like Growth Factor I; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D017526:Receptor, IGF Type 1; D040262:Receptors, Vascular Endothelial Growth Factor; D000109:Acetylcholine