Maintenance of tricarboxylic acid cycle kinetics in Brown-Norway Fischer 344 rats may translate to longevity

Glucose metabolism and tricarboxylic acid cycle (TCA) kinetics have been shown to decline in brain with age in various animal species. This study examined TCA cycle kinetics and age in Brown-Norway Fischer 344 rats. Using [1-C-13]glucose infused over 10, 30, 60 or 100 min, and following the label through the TCA cycle using H-1{C-13} spin-echo difference magnetic resonance spectroscopy, groups of 2 (n = 18), 12 (n = 16), and 24 (n = 16) month old rats were evaluated. Unexpectedly, TCA cycle kinetics did not change with age. Observed decreases in glutamate, glutamine and N-acetyl aspartate levels are consistent with an age-related decrease in neuronal numbers. The possible link between this observation and increased longevity, together with a decreased incidence of neoplasia in the Brown-Norway Fischer 344 rat is discussed. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.