Age-related changes in aldehyde reductase activity of rat brain, liver and heart

Aldehyde reductase (AR) activity was measured in the brain, liver and heart of 23- to 26-month-old and 3-month-old male Wistar rats, using 5 substrates (p-nitrobenzaldehyde, D-glucuronate, D-xylose, DL-glyceraldehyde and pyridine 3-aldehyde). A significant increase of AR activity was found in whole brain of old rats with p-nitrobenzaldehyde (11%) and D-glucuronate (24%). Results of experiments carried out with sodium valproate suggest that the AR activity increase in brain of old rats is the high-Km form. A significant increase of AR activity was found in cerebellum (26%), brainstem (19%), hypothalamus (13%), striatum (11%) and midbrain (6%) of old rats; up to now, the determination of the enzyme activity in the different brain regions has been carried out only with p-nitrobenzaldehyde. A significant increase of AR activity of old rats was also found in liver with D-glucuronate (10%), DL-glyceraldehyde (23%) and pyridine 3-aldehyde (30%), and in heart with p-nitrobenzaldehyde (42%) and DL-glyceraldehyde (20%). A significant decrease of AR activity with D-xylose (15%) was found in heart of old rats compared to matched animals of 3 months. The present study indicates that the regulatory mechanism for AR in brain and peripheral tissues like liver and heart are different with increasing age.