Age-related changes in sorbitol dehydrogenase activity of rat brain, liver, kidney and eye

Sorbitol dehydrogenase (SDH) activity was measured in whole brain, different brain areas, liver, kidney and eye of old rats (23-26 months) and compared with matched animals (3 months). A significant increase in SDH activity was found in whole brain (34%) of old rats, as well as in all brain areas studied: brainstem (59%), hypothalamus (38%), cerebral cortex (35%), striatum (30%), midbrain (27%), hippocampus (27%) and cerebellum (19%). The increase in SDH activity in brain of old rats is due to Vmax. These results do not favour an accumulation of sorbitol in brain of old rats. A significant decrease (36%) in SDH activity was found in kidney and no significant change in liver and eye of old rats when compared with young rats. Our previous and present results suggest that an accumulation of sorbitol might occur in some tissues of old rats, particularly in the eye, and cause cataract formation.