Effects of insulin treatment on endoneurial and systemic oxidative stress in relation to nerve conduction in streptozotocin-diabetic rats.
As increased oxidative stress is probably a pathogenetic factor in the development of diabetic complications, we studied nerve function and endogenous antioxidants in plasma, erythrocytes and sciatic nerve of untreated and insulin-treated streptozotocin-diabetic rats. After 18 weeks, the diabetes-induced sciatic nerve conduction velocity deficits were approximately 65% improved by insulin (P < 0.001). Plasma superoxide dismutase was significantly reduced in diabetes (P < 0.01); smaller decreases in plasma catalase and glutathione levels were observed. These changes were corrected by insulin treatment. In erythrocytes, decreased superoxide dismutase (P < 0.05) and increased total glutathione levels (P < 0.05) were found. All effects of diabetes, including a rise in plasma malonyldialdehyde (P < 0.05), were partially reversed by insulin treatment. In nervous tissue, diabetes caused increased catalase activity, uninfluenced by insulin (P < 0.05). Nerve superoxide dismutase and glutathione did not change. The data suggest that in diabetes, changes in systemic rather than endoneurial oxidative stress lead to nerve dysfunction.
van Dam
P S
PS
Rudolf Magnus Institute for Neurosciences, Utrecht University, The Netherlands.
Bravenboer
B
B
van Asbeck
B S
BS
van Oirschot
J F
JF
Marx
J J
JJ
Gispen
W H
WH
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002374:Catalase / Q000097:blood; D003921:Diabetes Mellitus, Experimental; D005978:Glutathione / Q000097:blood; D007328:Insulin / Q000627:therapeutic use*; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D009431:Neural Conduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D010525:Peripheral Nerves / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000097:blood; D013997:Time Factors
D000975:Antioxidants; D007328:Insulin; D008315:Malondialdehyde; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione