Holt P R, Heller T D, Richardson A G
Department of Medicine, St. Luke's/Roosevelt Hospital Center, New York.
J Gerontol. 1991 May;46(3):B89-94. doi: 10.1093/geronj/46.3.b89.
Previous studies have demonstrated that the specific activities of several proximal small intestinal mucosal enzymes fall in the aging rat. This reduction was due to a delay in the full expression of activity of these enzymes during epithelial cell transit from the crypt onto the intestinal villus. We now show in the ad libitum fed Fischer 344 rat that jejunal sucrase, maltase, and alkaline phosphatase specific activities do not fall gradually throughout the life span, but are reduced during senescence. Caloric restriction to 60% of ad libitum intake (DR) abolishes or delays this fall in enzyme activity. Jejunal mucosal immunoprecipitable sucrase-isomaltase (S-I) content also falls with age, but sucrase specific activity per molecule of S-I is less in the older ad libitum fed (approximately 45) than in the DR rats (approximately 60). Jejunal lactase activity falls gradually throughout the life span of ad libitum and DR rats, but lactase activity consistently was higher in DR animals. These observations indicate that DR alters the age-related changes in the activity of several enzymes in the rapidly replicating gut mucosa.
以往的研究表明，在衰老的大鼠中，几种近端小肠黏膜酶的比活性会下降。这种下降是由于这些酶在从隐窝到肠绒毛的上皮细胞转运过程中，其活性的完全表达出现延迟。我们现在在自由采食的Fischer 344大鼠中发现，空肠蔗糖酶、麦芽糖酶和碱性磷酸酶的比活性在整个生命周期中并非逐渐下降，而是在衰老过程中降低。将热量摄入限制为自由摄入量的60%（DR）可消除或延缓酶活性的这种下降。空肠黏膜中可免疫沉淀的蔗糖酶-异麦芽糖酶（S-I）含量也随年龄增长而下降，但每分子S-I的蔗糖酶比活性在自由采食的老年大鼠（约45）中低于DR大鼠（约60）。空肠乳糖酶活性在自由采食和DR大鼠的整个生命周期中逐渐下降，但DR动物的乳糖酶活性始终较高。这些观察结果表明，DR改变了快速复制的肠道黏膜中几种酶活性与年龄相关的变化。
