Diabetes, Vol 40, Issue 11 1545-1554, Copyright © 1991 by American Diabetes Association
Diminished specific activity of cytosolic protein kinase C in sciatic nerve of streptozocin-induced diabetic rats and its correction by dietary myo-inositol
J Kim, EH Rushovich, TP Thomas, T Ueda, BW Agranoff and DA Greene
Department of Biological Chemistry, University of Pittsburgh, Pennsylvania.
The impaired Na(+)-K(+)-ATPase activity in peripheral nerve from diabetic
rats is prevented by dietary myo-inositol (MI) supplementation in vivo and
corrected by protein kinase C (PKC) agonists in vitro, suggesting that PKC
may mediate the effects of nerve MI depletion on Na(+)-K(+)-ATPase
activity. However, little is known about the effect of diabetes on PKC
activity or peptide in rat peripheral nerve. Therefore, the effect of
streptozocin-induced diabetes and dietary MI supplementation on the
activity and distribution of PKC in rat sciatic nerve homogenates and
cytosolic and particulate fractions was explored with histone
phosphorylation assay and Western-blot analysis. PKC activity but not
peptide was selectively decreased in the cytosolic fraction by
streptozocin-induced diabetes, and this abnormality was partially corrected
by dietary MI supplementation. These results suggest that altered MI
metabolism may affect nerve PKC specific activity, and this alteration may
play a role in reduced Na(+)-K(+)-ATPase activity and blunted regenerative
response in diabetic nerve.