IMPAIRED FAD-GLYCEROPHOSPHATE DEHYDROGENASE-ACTIVITY IN ISLET AND LIVER HOMOGENATES OF FA FA RATS/

The mitochondrial FAD-linked enzyme glycerophosphate dehydrogenase pla ys a key role in the pancreatic B-cell glucose sensing device. In the present study, the activity of this enzyme was examined in islets of f a/fa rats in which inherited diabetes mellitus is associated with obes ity, hyperinsulinism and severe insulin resistance. The specific activ ity of both FAD-linked glycerophosphate dehydrogenase and glutamate de hydrogenase were decreased in islet and liver homogenates prepared fro m fa/fa, as compared to Fa/Fa, rats, this coinciding with a low ratio between glutamate-oxalacetate and glutamate-pyruvate transaminase acti vity in both islet and liver extracts, islet hyperplasia, hyperinsulin emia and hepatic steatosis in the hyperglycemic fa/fa rats. It is spec ulated that a low activity of FAD-linked glycerophosphate dehydrogenas e in the pancreatic B-cell may participate to the perturbation of gluc ose homeostasis in fa/fa rats, like in other animal models of non-insu lin-dependent diabetes mellitus.