Diabetes, Vol 40, Issue 3 344-348, Copyright © 1991 by American Diabetes Association
Changes in hepatic glutathione metabolism in diabetes
SV McLennan, S Heffernan, L Wright, C Rae, E Fisher, DK Yue and JR Turtle
Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, NSW, Australia.
Glutathione is important in the regulation of the redox state, and a
decline in its tissue level has often been considered to be indicative of
increased oxidative stress in diabetes. In this study of diabetic rats, the
level of hepatic glutathione was normal unless food intake was restricted.
Thus, the previous report of a reduction in hepatic glutathione in diabetes
is likely to be the result of food deprivation rather than diabetes alone.
In contrast to changes characteristic of oxidative stress, the efflux of
glutathione in bile from diabetic animals was significantly decreased,
whereas hepatic mixed disulfides were unchanged, and the hepatic
gamma-glutamyltransferase activity was considerably increased. These
changes were not reproduced by food deprivation. The decrease in biliary
excretion of glutathione in diabetes may reflect an attempt to conserve
glutathione by activation of the hepatic gamma-glutamyl cycle. We conclude
that the disturbances of glutathione metabolism in diabetes are not typical
of those seen in oxidative stress or food restriction.