Behav. young females). A comparison among the four groups of aged male mice (rapamycin Velneperit at 0, 4, 14, and Velneperit 42 ppm) showed a significant effect (= 0.02, pattern test for ordered categories). As shown in Fig. 1A, rapamycin leads to a dose-dependent decline in the incidence of liver degeneration in male mice, and the effect is dose dependent. Open in a separate windows Fig. 1 Incidence of liver degeneration (males only), myocardial nuclear atypia, endometrial hyperplasia (females only), and adrenal tumor in young, aged, and rapamycin-treated mice. Group Velneperit sizes were as follows: young, aged, and Rapa-Low, 15 of each sex; Rapa-Mid 14 females and 12 males; Rapa-High, 13 females and nine males. Fisher’s Exact Test was used to evaluate the significance of age effects (young vs. aged untreated), to compare Rapa (all doses) vs. aged (untreated), or to compare aged untreated vs. Rapa-high as indicated in the physique panels. Cuzick’s nonparametric test for trends (Cuzick, 1985) was used to evaluate significance of differences among the four groups of aged mice at rapamycin doses (zero, low, mid, or high). Atypical nuclei in cardiac myocytes Twenty three per cent of young mice and 70% of aged control mice had abnormalities of nuclear size and chromatin conformation in the myocardium (both sexes combined). Physique S1C,D shows representative sections, characterized by enlarged round or oval nuclei with clumped chromatin; more severe lesions include large multinucleated cells. The age effect, comparing young to aged controls, was significant at = 0.001. Rapamycin doses between 4.7 and 42 ppm were equally effective at lowering the incidence of these atypical nuclei (Fig. 1B), diminishing the frequency to 40/80 = 50% compared with 21/30 among aged controls. This difference is usually significant by the one-sided Fisher’s Exact Test at = 0.047. Endometrial cystic hyperplasia This lesion, that is, the growth of multiple large cysts within the uterine lining, was seen in 1/15 (7%) of young female controls, and in 13/15 (87%) of aged female controls (< 0.001). Representative sections are shown in Fig. S1E,F. Neither of the two lower rapamycin doses produced a significant diminution of the incidence of this lesion, but the highest rapamycin dose did lower the incidence (8/15 = 53%, = 0.05 compared with old controls; see Fig. 1C). Adrenal tumors Bmp1 Adrenal tumors were seen in 1/30 young mice (3%) and in 6/30 aged control mice (20%), with both sexes combined. The incidence among rapamycin-treated mice was 5/80 = 6%, and this proportion differs from that of the aged control group at = 0.04 by the one-sided Fisher Exact Test. A test for pattern among ordered groups (rapamycin doses of 0, 4.7, 14, 42 among the old mice) showed a significant trend at = 0.03. Physique 1D shows the proportion of mice with adrenal tumors. It is worth noting that adrenal tumors rarely contribute to death in UM-HET3 mice; only 1/31 control mice, and 0/40 rapamycin-treated mice were judged to have died because of adrenal tumors in an end-of-life necropsy series (Harrison = 6 young, 9 aged, and 17C20 aged rapamycin-treated mice. Small values differed from aged at = 0.002 for each endpoint by = 0.036 for maximum tangent modulus and at < 0.001 for hysteresis area. Thus, in summary, rapamycin significantly reduced the incidences of liver degenerative change, myocardial nuclear abnormalities, endometrial hyperplasia, and nonlethal adrenal tumors in 22-month-old mice, diminished the effects of aging around the biomechanical properties of tendon, and produced a numerical decrease in four of five other age-sensitive necropsy findings that did not achieve statistical significance. Rapamycin increases cataract severity Cataract severity was scored on a scale of 0C3 by slit lamp examination in unanesthetized mice at 20 months of age by an ophthalmologist (MW) who was unaware of the treatment condition. Scores for left and right eyes were.