Effects of propionyl-L-carnitine and insulin on the electroretinogram, nerve conduction and nerve blood flow in rats with streptozotocin-induced diabetes.
The effect of an analogue of L-carnitine, propionyl-L-carnitine, on the electroretinogram, motor nerve conduction velocity and nerve blood flow was determined in rats with streptozotocin-induced diabetes, and was compared with the effects of insulin alone or combined therapy. Oral administration of propionyl-L-carnitine (3 g/kg daily for 4 weeks) significantly increased caudal nerve motor conduction velocity and sciatic nerve blood flow in diabetic rats. There were no differences in the effects of insulin (8-10 U daily for 4 weeks), propionyl-L-carnitine and combined therapy. Although propionyl-L-carnitine significantly shortened the peak latency of the electroretinogram b-wave in diabetic rats, its effect was far weaker than that of insulin or combined therapy, with combined therapy producing the greatest improvement. These effects of propionyl-L-carnitine were accompanied by a decrease of serum lipid levels, an increase of the sciatic nerve carnitine content, and no changes of the tissue (nerve and retinal) sorbitol and myo-inositol concentrations. In contrast, insulin significantly reduced the tissue sorbitol content and markedly increased myo-inositol. These findings suggest that propionyl-L-carnitine may improve diabetic neuropathy and retinopathy without influencing the polyol pathway, and that this beneficial effect may be mediated through the amelioration of microcirculation and tissue carnitine content, thus probably increasing fatty acid oxidation.
Hotta
N
N
Third Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Koh
N
N
Sakakibara
F
F
Nakamura
J
J
Hamara
Y
Y
Hara
T
T
Nakashima
E
E
Sasaki
H
H
Fukasawa
H
H
Kakuta
H
H
Sakamoto
N
N
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D002316:Cardiotonic Agents / Q000494:pharmacology; D002331:Carnitine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000503:physiopathology*; D004359:Drug Therapy, Combination; D004596:Electroretinography; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D008055:Lipids / Q000097:blood; D008297:Male; D009431:Neural Conduction / Q000187:drug effects*; D011108:Polymers / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects; D012160:Retina / Q000737:chemistry; D012171:Retinal Vessels / Q000502:physiology*; D012584:Sciatic Nerve / Q000098:blood supply / Q000737:chemistry; D013012:Sorbitol / Q000378:metabolism
D001786:Blood Glucose; D002316:Cardiotonic Agents; D007004:Hypoglycemic Agents; D007328:Insulin; D008055:Lipids; D011108:Polymers; C024617:polyol; C003223:propionylcarnitine; D013012:Sorbitol; D002331:Carnitine