X-Message-Number: 26593 Date: Tue, 12 Jul 2005 20:02:09 -0700 (PDT) From: Doug Skrecky <> Subject: exercise stops muscle aging [Curiously, exercise does not increase maximum lifespan in rodents. This implies that maximum lifespan is not determined by muscle tissue in these animals. By contrast, in nematodes muscle tissue does appear to be linked to maximum lifespan. In drosophila flies, motor neurons are the determining factor. The critical tissue for rodent maximum longevity is currently unknown. There is some evidence to indicate that in humans the major lifespan determining tissue may be bone marrow.] Habitual exercise program protects murine intestinal, skeletal, and cardiac muscles against aging epub June 16, 2005 Aging and aerobic exercise are two conditions known to interfere with health and quality of life, most likely by inducing oxidative stress to the organism. We studied the effects of aging on the morphological and functional properties of skeletal, cardiac, and intestinal muscles, and their corresponding oxidative status, in C57BL/6 mice, and investigated whether a lifelong moderate exercise program would exert a protective effect against some deleterious effects of aging. As expected, aged animals presented a significant reduction of physical performance, accompanied by a decrease of gastrocnemius cross-sectional area, and cardiac hypertrophy. However, the most interesting was that aging dramatically interfered with the intestinal structure, causing a significant thickening of the ileum muscular layer. Senescent intestinal myocytes displayed many mitochondria with disorganized cristae, and the presence of cytosolic lamellar corpuscules. Lipid peroxidation of ileum and gastrocnemius muscle, but not of the heart, increased in aged mice, thus suggesting enhanced oxidative stress. With exception of the intestinal muscle responsiveness, animals submitted to a daily session of 60 min, 5 days/week, at 13 up to 21m/min of moderate running in treadmill during animal life span exhibited a reversion of all the observed aging effects on intestinal, skeletal, and heart muscles. The introduction of this lifelong exercise protocol prevented the enhancement of lipid peroxidation and sarcopenia, and also preserved cellular and ultra-cellular structures of the ileum. This is the first time that the protective effect of a lifelong regular aerobic physical activity against the deleterious effects of aging on intestinal muscle was demonstrated. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26593