Hagopian Kevork, Ramsey Jon J, Weindruch Richard
Department of Molecular Biosciences, School of Veterinary Medicine, University of California, One Shields Ave, Davis, CA 95616, USA.
FEBS Lett. 2005 Mar 28;579(9):2009-13. doi: 10.1016/j.febslet.2005.02.062.
The influence of caloric restriction (CR) on the activities of hepatic serine metabolizing enzymes in young (3 months) and old (30 months) mice was studied. Serine dehydratase (SDH) activity increased markedly with age in both diet groups and in old mice was higher in the CR group. No effects of CR were observed in the young. Serine:pyruvate transaminase (SPT) and glycerate kinase activities were unaffected by age and diet. However, glycerate dehydrogenase activity was decreased in old CR mice but not in young CR. The results of this study show that long-term CR influenced serine utilization only in the pathway catalyzed by SDH. This suggests that in mouse liver this pathway is critical for serine utilization in gluconeogenesis, while the SPT pathway plays a minor role. The increase in SDH activity with long-term CR is consistent with sustained increase in gluconeogenesis.
研究了热量限制（CR）对年轻（3个月）和老年（30个月）小鼠肝脏丝氨酸代谢酶活性的影响。在两个饮食组中，丝氨酸脱水酶（SDH）活性均随年龄显著增加，且在老年小鼠中，CR组的SDH活性更高。在年轻小鼠中未观察到CR的影响。丝氨酸：丙酮酸转氨酶（SPT）和甘油酸激酶活性不受年龄和饮食的影响。然而，老年CR小鼠的甘油酸脱氢酶活性降低，而年轻CR小鼠未降低。本研究结果表明，长期CR仅在由SDH催化的途径中影响丝氨酸利用。这表明在小鼠肝脏中，该途径对糖异生中丝氨酸的利用至关重要，而SPT途径起次要作用。长期CR导致的SDH活性增加与糖异生的持续增加一致。
