Reduced motor nerve conduction velocity and Na(+)-K(+)-ATPase activity in rats maintained on L-fucose diet. Reversal by myo-inositol supplementation.
L-Fucose is a monosaccharide that occurs in low concentrations in normal serum but has been shown to be increased in diabetic individuals. In cultured mammalian cells, L-fucose is a potent competitive inhibitor of myo-inositol transport. Abnormal myo-inositol metabolism has been proposed to be a factor in the development of diabetic complications. To test the hypothesis that myo-inositol deficiency may be responsible for the electrophysiological and biological defects in diabetic neuropathy, rats were fed a diet containing 10 or 20% L-fucose for a period of 6 wk. After 3 wk, the L-fucose diets in two groups of rats were supplemented with 1% myo-inositol. At the end of the study protocol, motor nerve conduction velocity, sciatic nerve tissue Na(+)-K(+)-ATPase activity, and myo-inositol content were determined. These results were compared with those of STZ-induced diabetic rats fed either a normal diet or a diet containing 1% myo-inositol or with those given 450 mg/kg body wt of sorbinil. Serum L-fucose levels were significantly increased in rats fed a diet containing 10 or 20% L-fucose. In comparison, the serum L-fucose levels in the diabetic rats were increased to a lesser extent. Motor nerve conduction velocity was significantly slower in rats fed a 10 or 20% L-fucose diet. Sciatic nerve composite and ouabain-sensitive Na(+)-K(+)-ATPase activity and myo-inositol content was also significantly decreased. Supplementation of 1% myo-inositol to the L-fucose-containing diet restored nerve myo-inositol levels and significantly improved Na(+)-K(+)-ATPase activity and motor nerve conduction velocity.(ABSTRACT TRUNCATED AT 250 WORDS)
Yorek
M A
MA
Department of Internal Medicine, University of Iowa, Iowa City.
Wiese
T J
TJ
Davidson
E P
EP
Dunlap
J A
JA
Stefani
M R
MR
Conner
C E
CE
Lattimer
S A
SA
Kamijo
M
M
Greene
D A
DA
Sima
A A
AA
D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology / Q000503:physiopathology; D003929:Diabetic Neuropathies / Q000503:physiopathology / Q000517:prevention & control; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005643:Fucose / Q000008:administration & dosage* / Q000032:analysis / Q000097:blood; D007093:Imidazoles / Q000494:pharmacology; D048289:Imidazolidines; D007294:Inositol / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology*; D008297:Male; D009046:Motor Neurons / Q000201:enzymology* / Q000502:physiology*; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology*; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000737:chemistry; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000502:physiology*; D013311:Streptozocin; D013997:Time Factors
D004040:Dietary Carbohydrates; D007093:Imidazoles; D048289:Imidazolidines; D005643:Fucose; D007294:Inositol; D010042:Ouabain; D013311:Streptozocin; D000254:Sodium-Potassium-Exchanging ATPase; C026411:sorbinil