Young Sedentary Research Articles

Swimming exercise reverses transcriptomic changes in aging mouse lens

BackgroundThe benefits of physical activity for the overall well-being of elderly individuals are well-established, the precise mechanisms through which exercise improves pathological changes in the aging lens have yet to be fully understood.Methods3-month-old C57BL/6J mice comprised young sedentary (YS) group, while aging mice (18-month-old) were divided into aging sedentary (AS) group and aging exercising (AE) group. Mice in AE groups underwent sequential stages of swimming exercise. H&E staining was employed to observe alterations in lens morphology. RNA-seq analysis was utilized to examine transcriptomic changes. Furthermore, qPCR and immunohistochemistry were employed for validation of the results.ResultsAE group showed alleviation of histopathological aging changes in AS group. By GSEA analysis of the transcriptomic changes, swimming exercise significantly downregulated approximately half of the pathways that underwent alterations upon aging, where notable improvements were ‘calcium signaling pathway’, ‘neuroactive ligand receptor interaction’ and ‘cell adhesion molecules’. Furthermore, we revealed a total of 92 differentially expressed genes between the YS and AS groups, of which 10 genes were observed to be mitigated by swimming exercise. The result of qPCR was in consistent with the transcriptome data. We conducted immunohistochemical analysis on Ciart, which was of particular interest due to its dual association as a common aging gene and its significant responsiveness to exercise. The Protein-protein Interaction network of Ciart showed the involvement of the regulation of Rorb and Sptbn5 during the process.ConclusionThe known benefits of exercise could extend to the aging lens and support further investigation into the specific roles of Ciart-related pathways in aging lens.

Age-related changes in adipose tissue metabolomics and inflammation, cardiolipin metabolism, and ferroptosis markers in female aged rat model

Aging adipose tissue exhibits elevated inflammation and oxidative stress that are major sources of age-related metabolic dysfunction. However, the exact metabolic changes associated with inflammation and oxidative stress are unclear. To address this topic, we assessed variation in metabolic phenotypes of adipose tissue from 18 months adult sedentary (ASED), 26 months old sedentary (OSED), and 8 months young sedentary (YSED). The results of metabolomic analysis showed that ASED and OSED group had higher palmitic acid, elaidic acid, 1-heptadecanol, and α-tocopherol levels than YSED, but lower sarcosine levels. Furthermore, stearic acid was specifically elevated in ASED compared with YSED. Cholesterol was upregulated specifically in the OSED group compared with YSED, whereas linoleic acid was downregulated. In addition, ASED and OSED had more inflammatory cytokines, lower antioxidant capacity, and higher expression of ferroptosis-related genes than YSED. Moreover, mitochondrial dysfunction associated with abnormal cardiolipin synthesis was more pronounced in the OSED group. In conclusion, both ASED and OSED can affect the FA metabolism and increase oxidative stress in adipose tissue, leading to inflammation. In particular, linoleic acid content specifically decreases in OSED, which associated with abnormal cardiolipin synthesis and mitochondrial dysfunction in adipose tissue.

Midlife aerobic exercise and brain structural integrity: Associations with age and cardiorespiratory fitness

Lower midlife physical activity is associated with higher risk of neurodegenerative disease in late life. However, it remains unknown whether physical exercise and fitness are associated with brain structural integrity during midlife. The purpose of this study was to compare brain structures between middle-aged aerobically trained adults (MA), middle-aged sedentary (MS), and young sedentary (YS) adults. Thirty MA (54±4 years), 30 MS (54±4 years), and 30 YS (32±6 years) participants (50% women) underwent measurements of brain volume, cortical thickness, and white matter (WM) fiber integrity using MRI. MA participants had aerobic training for 24.8±9.6 years and the highest cardiorespiratory fitness level (i.e., peak oxygen uptake: VO2peak) among all groups. Global WM integrity, as assessed with fractional anisotropy (FA) from diffusion tensor imaging, was lower in the MS compared with the YS group. However, global FA in the MA group was significantly higher than that in the MS group (P<0.05) and at a similar level to the YS group. Furthermore, tract-based spatial statistical analysis demonstrated that FA in the anterior, superior, and limbic WM tracts (e.g., the genu of the corpus callosum, superior longitudinal fasciculus, uncinate fasciculus) was higher in the MA compared with MS groups, and positively associated with VO2peak, independently from age and sex. From cortical thickness analysis, MS and MA participants showed thinner prefrontal and parieto-temporal areas than the YS group. On the other hand, the MA group exhibited thicker precentral, postcentral, pericalcarine, and lateral occipital cortices than the MS and YS groups. But, the insula and right superior frontal gyrus showed thinner cortical thickness in the MA compared with the MS groups. Collectively, these findings suggest that midlife aerobic exercise is associated with higher WM integrity and greater primary motor and somatosensory cortical thickness.

Effects of short-term physical training on the interleukin-15 signalling pathway and glucose tolerance in aged rats

PurposeInterleukin-15 (IL-15) is a myokine that has been proposed to modulate skeletal muscle and adipose tissue mass, as well as insulin sensitivity. However, the evidence suggesting a role for IL-15 in improving whole-body insulin sensitivity and decreasing adiposity comes mainly from studies using supraphysiological levels of this cytokine. This study examined the effect of a short-term exercise training protocol on the protein content of IL-15, it's signaling pathway, and glucose tolerance in aged rats. MethodsFourteen Wistar rats were divided into Young Sedentary (Young, n = 4); Old Sedentary (Old, n = 5); Old Exercise (Old.Exe, n = 5) groups. The animals from the exercised group were submitted to a short-term physical exercise protocol for five days. At the end of physical training and after 16 h of the last exercise session, the animals were euthanized, and tissue collection was done. ResultsPhysical exercise decreased epididymal and mesenteric fat mass and promoted positive effects on glucose tolerance and insulin sensitivity. Muscle IL-15 protein levels were not changed following the short-term physical exercise training with no alterations in the post-exercise IL-15–JAK/STAT signaling pathway. We found a tendency to increased HIF1α and a significant increase in its regulator, PHD2, in the skeletal muscle after exercise. ConclusionThe elderly rats submitted to short-term aerobic physical training did not present skeletal muscle alteration in the protein content of the IL-15 and IL-15-JAK/STAT signaling pathway. However, short-term aerobic physical training was able to modulate the expression of HIF1α and its regulator PHD2, suggesting an essential role of these proteins in improving post-exercise glucose tolerance and insulin sensitivity in elderly rats.

Remodeling process in bone of aged rats in response to resistance training

AimsWe investigate the effects of RT on the mechanical function, gene, and protein expression of key factors involved in bone remodeling during aging. Main methodsMale rats of 3 and 21 months of age were randomly allocated into four groups (8 per group): young sedentary (YS), young trained (YT), old sedentary (OS), and old trained (OT). RT was performed three times per week (12 weeks). Bone tenacity and stiffness were measured by biomechanical tests and mRNA levels of COL1A1, MEPE, SOST, OPG, BMP-2, PPAR-y, MMP-2-9-13, and TIMP-1 were evaluated by quantitative PCR. COL1A1 protein and MMP-2 activity were detected by western blotting and zymography assays. Key findingsAging increased stiffness, while BMP-2, OPG, COL1A1 and MMP-2 mRNA levels reduced (OS vs YS; p ≤ 0.05). RT increased the tenacity of the femur and reduced PPAR-γ regardless of age (YT vs. YS; OT vs. OS; p ≤ 0.05). RT downregulated SOST mRNA levels only in the OT group (vs. OS group, p ≤ 0.05). RT mitigated the age-associated increase in MMP-9 mRNA levels (p ≤ 0.05). In young animals, upregulation in MEPE, MMP-13, TIMP-1 were observed after RT, as well an increase in COL1A1 protein and MMP-2 activity (p ≤ 0.05). SignificanceRT improved bone tenacity independent of aging, which is relevant for mechanical function, while, at protein levels, RT upregulated MMP-2 activity and collagen 1 only in young rats. This study highlights the importance of exercise on bone health and identifies specific molecular changes in response to RT. Our findings provide insights into the mechanisms involved in age-related changes.

Regular Endurance Exercise Promotes Fission, Mitophagy, and Oxidative Phosphorylation in Human Skeletal Muscle Independently of Age.

This study investigated whether regular endurance exercise maintains basal mitophagy and mitochondrial function during aging. Mitochondrial proteins and total mRNA were isolated from vastus lateralis biopsies (n = 33) of young sedentary (YS), old sedentary (OS), young active (YA), and old active (OA) men. Markers for mitophagy, fission, fusion, mitogenesis, and mitochondrial metabolism were assessed using qRT-PCR, Western blot, and immunofluorescence staining. Independently of age, fission protein Fis1 was higher in active vs. sedentary subjects (+80%; P < 0.05). Mitophagy protein PARKIN was more elevated in OA than in OS (+145%; P = 0.0026). mRNA expression of Beclin1 and Gabarap, involved in autophagosomes synthesis, were lower in OS compared to YS and OA (P < 0.05). Fusion and oxidative phosphorylation proteins were globally more elevated in the active groups (P < 0.05), while COx activity was only higher in OA than in OS (P = 0.032). Transcriptional regulation of mitogenesis did not vary with age or exercise. In conclusion, physically active lifestyle seems to participate in the maintenance of lifelong mitochondrial quality control by increasing fission and mitophagy.

Effects of Resistance Training on Matrix Metalloproteinase Activity in Skeletal Muscles and Blood Circulation During Aging

Aging is a complex, multifactorial process characterized by the accumulation of deleterious effects, including biochemical adaptations of the extracellular matrix (ECM). The purpose of this study was to investigate the effects of 12 weeks of resistance training (RT) on metalloproteinase 2 (MMP-2) activity in skeletal muscles and, MMP-2 and MMP-9 activity in the blood circulation of young and old rats. Twenty-eight Wistar rats were randomly divided into four groups (n = 7 per group): young sedentary (YS); young trained (YT), old sedentary (OS), and old trained (OT). The stair climbing RT consisted of one training session every 2 other day, with 8–12 dynamic movements per climb. The animals were euthanized 48 h after the end of the experimental period. MMP-2 and MMP-9 activity was measured by zymography. There was higher active MMP-2 activity in the lateral gastrocnemius and flexor digitorum profundus muscles in the OT group when compared to the OS, YS, and YT groups (p ≤ 0.001). Moreover, there was higher active MMP-2 activity in the medial gastrocnemius muscle in the OT group when compared to the YS and YT groups (p ≤ 0.001). The YS group presented lower active MMP-2 activity in the soleus muscle than the YT, OS, OT groups (p ≤ 0.001). With respect to active MMP-2/9 activity in the bloodstream, the OT group displayed significantly reduced activity (p ≤ 0.001) when compared to YS and YT groups. In conclusion, RT up-regulates MMP-2 activity in aging muscles, while down-regulating MMP-2 and MMP-9 in the blood circulation, suggesting that it may be a useful tool for the maintenance of ECM remodeling.

Resistance training minimizes the biomechanical effects of aging in three different rat tendons

Aging process is characterized by a decline in the organism functionality, especially in the decrease of muscle function, which also affects tendons. On the other hand, the resistance training (RT) has been used as an important tool to increase muscle and tendineous function during aging. Thus, this study aim has been to verify the effects of RT on the biomechanical properties of three different aged rat tendons. For this purpose, 20 wistar rats have been divided into four groups (5 rats per group): young sedentary (YS), trained (YT), old sedentary (OS) and old trained (OT). The RT has been performed through climb protocol for 12 weeks. After RT, the calcaneal tendon (CT), superficial flexor tendon (SFT) and deep flexor tendon (DFT) have been used for analysis. The results indicate that the RT in aged rats can prevent tendon function decrease (p<0.05). Although RT has prompted significant biomechanical changes in trained aged rats, there has been no increase in cross-section area or tendon stiffness reduction. Thus, the OT group showed better biomechanical responses when compared with OS (p<0.05). Therefore, RT can be used as an excellent strategy for increasing in tendon capacity during aging.

Physical Activity And Passive Leg Movement-Induced Vasodilation

The vasodilatory response to passive leg movement (PLM) is predominantly nitric oxide (NO) mediated. Due to reduced NO bioavailability with advancing age, PLM-induced vasodilation is attenuated in older sedentary subjects. PURPOSE: We sought to determine the impact of varying levels of physical activity on PLM-induced vasodilation, and therefore NO bioavailability, in older subjects. METHODS: PLM was performed on four subject groups (young sedentary (YS), 23 ± 1 yrs, n = 12; old sedentary (OS), 73 ± 2 yrs, n = 12; old active (OA), 71 ± 2 yrs, n = 10; old endurance trained (OT), 72 ± 1 yrs, n = 10) in the upright-seated posture. Central and peripheral hemodynamic responses were determined second-by-second with finger photoplethysmography and Doppler ultrasound, respectively. RESULTS: Peak VO2 was significantly different between all subject groups (YS = 42 ± 3, OS = 26 ± 2, OA = 34 ± 2, OT = 52 ± 2 ml/kg/min; P < 0.05). PLM-induced peak change in leg vascular conductance (ΔLVCpeak) was significantly attenuated in OS compared to YS (OS: 4.4 ± 0.8, YS: 11.8 ± 1.3 ml/min/mmHg; P < 0.05). Both OA and OT groups demonstrated augmented ΔLVCpeak compared to OS (OA: 7.3 ± 0.8, OT: 7.6 ± 0.9 ml/min/mmHg; P < 0.05). However, OA and OT groups were not different (P = 0.82), and remained attenuated compared to YS (P < 0.05). The rapid vasodilatory response (slope of LVC over time; ml/min/mmHg/s), also thought to be partially NO-dependent, was not different between YS, OA, and OT (YS: 1.08 ± 0.14, OA: 0.75 ± 0.10, OT: 0.79 ± 0.14 ml/min/mmHg/s; P < 0.05), but was decreased in OS compared to the other three groups (0.42 ± 0.06 ml/min/mmHg/s; P < 0.05). CONCLUSIONS: These data suggest that remaining physically active during aging likely augments NO-mediated vascular function. However, physical activity, even at levels achieved by highly trained older individuals, failed to fully restore vasodilatory responses to that of the young.

Exercise Attenuates Age‐Associated Reductions in Muscle Strength and Cardiorespiratory Fitness in Mice

Aging is associated with losses in muscle strength and cardiovascular fitness that may be offset with regular exercise. While exercise adaptations may diminish with age, robust adaptations still occur. We tested the hypothesis that aging reduces muscle function and cardiorespiratory endurance, however voluntary (running wheel, RW) or prescribed (treadmill (TM) training) exercise will attenuate these aging‐associated decreases in strength and fitness. In vivo plantarflexor maximal force and fatigue (% of max force after 10 contractions) were measured in young (4 mo. old) and aged (24 mo. old) sedentary (SED) mice and following 2 wks of RW (24h wheel access) or TM training (45 min/day, 5 day/wk). Cardiorespiratory adaptations were assessed with pre‐ and post‐maximal treadmill tests. Maximal muscle force was lower in aged than young SED mice (1.1±0.04 vs. 1.6±0.07 g/kg BW, respectively, p&lt;0.05). In young groups, neither RW nor TM increased force over SED. In aged groups, RW and TM were associated with respective 22 and 26% higher maximal forces than aged SED mice (p&lt;0.05), but still were lower than young groups. Plantarflexor fatigue resistance was higher in aged than young SED mice (50±3 vs. 35±3% of max, respectively, p&lt;0.05) with no age differences in RW and TM groups. In treadmill pre‐tests, young groups ran longer than aged groups (9:23±0:52 vs. 5:09± 0:51, respectively p&lt;0.05). Increases in treadmill time after training occurred only in young and aged TM with respective 25:34±8:24 and 16:42±2:39 increases from pre to post test (p&lt;0.05). These findings suggest voluntary and prescribed exercise attenuate some age‐associated reductions in muscle force, but prescribed exercise is most effective in improving cardiorespiratory fitness in young and older mice.

Aging and exercise training reduce testes microvascular Po2and alter vasoconstrictor responsiveness in testicular arterioles

Testicular function and associated testosterone concentration decline with advancing age, and an impaired O₂ supply may contribute, in part, to this reduction. We hypothesized that there would be a reduced microvascular Po₂ (Po₂(m)) in the testes from aged rats, and this reduced Po₂(m) would be associated with impaired vasomotor control in isolated resistance arterioles. In addition, given the positive effect of exercise on microvascular Po₂ and arteriolar function, we further hypothesized that there would be an enhanced Po₂(m) in the testes from aged animals after aerobic exercise training. Testicular Po₂(m) was measured in vivo via phosphorescence quenching in young and aged sedentary (SED) and exercise-trained (ET; 15 m/min treadmill walking, 15-degree incline, 5 days/wk for 10 wk) male Fischer-344 rats. Vasoconstriction to α-adrenergic [norepinephrine (NE) and phenylephrine (PE)] and myogenic stimuli in testicular arterioles was assessed in vitro. In the SED animals, testicular Po₂(m) was reduced by ∼50% with old age (aged SED 11.8 ± 1.9 vs. young SED 22.1 ± 1.1 mmHg; P = 0.0001). Contrary to our hypothesis, exercise training did not alter Po₂(m) in the aged group and reduced testicular Po₂(m) in the young animals, abolishing age-related differences (young ET, 10.0 ± 0.8 vs. aged ET, 10.7 ± 0.9 mmHg; P = 0.37). Vasoconstrictor responsiveness to NE and PE was diminished in aged compared with young (NE: young SED, 58 ± 2 vs. aged SED, 47 ± 2%; P = 0.001) (PE: young SED, 51 ± 3 vs. aged SED, 36 ± 5%; P = 0.008). Exercise training did not alter maximal vasoconstriction to NE in young or aged groups. In summary, advancing age is associated with a reduced testis Po₂(m) and impaired adrenergic vasoconstriction. The diminished testicular microvascular driving pressure of O₂ and associated vascular dysfunction provides mechanistic insight into the old age-related decrease in testicular function, and a reduced Po₂(m) may contribute, in part, to reduced fertility markers after exercise training.

Resistance training improves femoral artery endothelial dysfunction in aged rats

Although endurance exercise improves age-associated endothelial dysfunction, few studies have examined the effects of resistance training and the potential molecular mechanisms involved in altering vascular reactivity with age. Young (9 months) and aged (20 months) male, Fisher 344 rats were divided into four groups: Young Sedentary (YS, n = 14), Young Trained (YT, n = 10), Aged Sedentary (AS, n = 12), and Aged Trained (AT, n = 10). Resistance training consisted of climbing a 1 m wire ladder, at an 85 degrees angle, 3 days/week for 6 weeks with increasing weight added to the tail. Endothelial function in femoral arteries was determined by constructing acetylcholine dose-response curves on a wire myograph. Femoral artery phospho-Ser1179-eNOS, eNOS and Hsp90 expression were evaluated by Western blot. Acetylcholine-induced vasorelaxation was significantly (P < 0.05) impaired in AS compared to YS and YT but not AT compared to YS and YT. Phospho-Ser1179-eNOS and eNOS were elevated (P < 0.05) in aged animals but not changed with resistance training. Resistance training increased Hsp90 levels in both young and old animals. Therefore, resistance training improves age-associated endothelial dysfunction in femoral arteries without changes in eNOS phosphorylation and expression. Increased Hsp90 expression, a regulator of eNOS activity and coupling, suggests a potential mechanism for this improvement.

Effects of ageing and exercise training on eNOS uncoupling in skeletal muscle resistance arterioles

Reduced availability of tetrahydrobiopterin (BH(4)) contributes to the age-related decline of nitric oxide (NO)-mediated vasodilatation of soleus muscle arterioles. Depending on availability of substrate and/or necessary co-factors, endothelial nitric oxide synthase (eNOS) can generate NO and/or superoxide (O(2)(-)). We evaluated the effects of age and chronic exercise on flow-induced vasodilatation and levels of NO and O(2)(-) in soleus muscle arterioles. Young (3 months) and old (22 months) male rats were exercise trained or remained sedentary (SED) for 10 weeks. Flow-stimulated NO and O(2)(-), as well as BH(4) and l-arginine content, were determined in soleus muscle arterioles. Flow-induced vasodilatation was assessed under control conditions and during the blockade of O(2)(-) and/or hydrogen peroxide. Exercise training enhanced flow-induced vasodilatation in arterioles from young and old rats. Old age reduced, and exercise training restored, BH(4) content and flow-stimulated NO availability. Flow-stimulated, eNOS-derived O(2)(-) levels were higher in arterioles from old SED compared to those from young SED rats. Exercise training increased flow-stimulated eNOS-derived O(2)(-) levels in arterioles from young but not old rats. O(2)(-) scavenging with Tempol reduced flow-induced vasodilatation from all groups except young SED rats. Addition of catalase to Tempol-treated arterioles eliminated flow-induced vasodilatation in arterioles from all groups. Catalase reduced flow-induced vasodilatation from all groups. In Tempol-treated arterioles, flow-induced vasodilatation was restored by deferoxamine, an iron chelator. These data indicate that uncoupling of eNOS contributes to the age-related decline in flow-induced vasodilatation; however, reactive oxygen species are required for flow-induced vasodilatation in soleus muscle arterioles from young and old rats.

Vascular reactivity in femoral arteries of aged rats following resistance exercise training

Previous studies have demonstrated an increase in arterial stiffness and endothelial dysfunction in aging arteries. Although it is well known that resistance training counteracts losses of muscular strength with age and subsequent loss in quality of life, few studies have examined the effects of resistance training on vascular function. Young (9 mo) and aged (24 mo) male, Fisher 344 rats were divided into four groups: Young Sedentary (YS, n=10), Young Trained (YT, n=10), Aged Sedentary (AS, n=9), and Aged Trained (AT, n=9). Resistance training consisted of climbing a 1 m wire ladder, at an 85o angle, 3d/wk for 7 weeks with increasing weight added to the tail. Vascular reactivity was examined by constructing dose response curves to phenylephrine (PE, 10−7‐10−4 M), sodium nitroprusside (SNP, 10−8‐10−5 M), and acetylcholine (ACh, 10−7‐3x10−5 M). Vasocontrictor responses to PE were significantly (P&lt;0.05) greater in Aged versus Young. Vasodilator responses to both SNP and ACh were significantly impaired in AS but were improved in AT. In conclusion, these data suggest that resistance exercise training results in a shift in the vasoreactivity of aged animals towards that of younger animals which includes both a blunted vasoconstrictor response and enhanced vasorelaxation. The mechanisms underlying this shift remain to be determined. Supported by NIH R15 HL082649‐01 (MBH) and the Borgenicht Program for Aging Studies and Exercise Science (MBH).

Exercise Training Modulates the Nitric Oxide Synthase Profile in Skeletal Muscle From Old Rats

The effects of exercise training on the nitric oxide synthase (NOS) isoform profile in aging fast-twitch (white gastrocnemius [WG]) and slow-twitch (soleus [SOL]) muscle have not been investigated. Six-month and 27-month male Fischer-344 rats were divided into the following groups: young sedentary (YS), young treadmill exercise trained for 12 weeks, old sedentary (OS), and old exercise trained (OE). Inducible NOS (iNOS) protein expression and activity were significantly higher in OS compared with YS, whereas exercise training significantly reduced iNOS protein and activity levels in the WG. Neuronal NOS protein expression decreased with aging in WG but was upregulated significantly with exercise training in OE for both WG and SOL. Endothelial NOS (eNOS) protein levels were depressed in WG of old rats but were higher in OE than in OS. eNOS was unaffected by aging or exercise in the SOL. Our results indicate that endurance exercise training attenuates age-induced alterations of NOS isoforms with a greater response in fast-twitch compared with slow-twitch muscle.

Exercise training inducibility of MnSOD protein expression and activity is retained while reducing prooxidant signaling in the heart of senescent rats

While the stress response to heat and exercise is limited in the heart with progressive aging, recent data indicate that acute or short-term exercise upregulates the Mn isoform of superoxide dismutase (MnSOD), which may provide protection against ischemia-reperfusion injury and cell death by reducing oxidative stress. Growing evidence indicates that inducible nitric oxide synthase (iNOS) contributes to age-induced increases in oxidative stress and risk of heart failure. We postulated that oxidative stress and iNOS levels would be related to the ability of the aging heart to upregulate MnSOD in response to long-term exercise training. Six- and twenty-seven-mo-old Fischer-344 rats had been assigned to young sedentary (YS), young exercise (YE), old sedentary (OS), or old exercise (OE) groups. ET groups ran on a treadmill for 60 min/day, 5 days/wk for a total of 12 wk. MnSOD protein expression in the left ventricle was increased (+43%) by 12 wk of exercise training in the old age group, with no changes in Cu,ZnSOD. Exercise training also increased MnSOD activity in left ventricles from old and young rats. HSP70 was inducible by exercise training in hearts exclusively from the young age group. iNOS protein expression increased markedly with aging (+548%), while exercise training decreased iNOS levels by -73% in OE compared with OS. In addition, 4-hydroxynonenal protein adducts in the left ventricle increased by 237% with aging, while 12 wk of exercise training resulted in attenuation (-55%). These data indicate that inducibility of MnSOD is preserved with long-term exercise training in the aging rat heart. Moreover, upregulation of MnSOD in the aging heart was directly associated with attenuated levels of oxidative stress, including iNOS.

The Impact of Long‐Term Physical Activity on Age‐Related Changes in Protein and Gene Expression

Age‐related mitochondrial dysfunction is paralleled by reductions in gene transcripts and expression of proteins involved in cellular ATP production. Short‐term endurance exercise has been shown to enhance muscle protein synthesis in the elderly. We determined the impact of long‐term endurance exercise on gene expression and protein abundance of numerous proteins involved in cellular energetics. Vastus lateralis tissue was biopsied from 11 young sedentary (YS), 10 old sedentary (OS), 11 young trained (YT), and 11 old trained (OT) subjects. Trained subjects vigorously exercised ¡Ý 1 hr/d, ¡Ý five d/wk for ¡Ý 4 years. Large‐scale measurement of relative protein abundance was performed using isobaric tags for relative and absolute quantitation (iTRAQ) reagents and tandem mass spectrometry. Gene transcript levels were measured by high‐density oligonucleotide microarrays. Ingenuity Pathway Analysis was used to determine canonical pathways that were altered by age. Of the 33 proteins involved in cellular ATP production 27 were less abundant in OS vs. YS, while only 4 of these proteins were less abundant in OT vs. YT. Genes involved in glycolysis and oxidative phosphorylation were underexpressed in OS vs. YS, with no effects of age in OT vs. YT. CONCLUSIONS: Long‐term vigorous endurance exercise ameliorates the detrimental effects of old age on muscle gene and protein expression in humans.

Effect of Aging and Exercise Training on Matrix Metalloproteinases in Rat Heart

Aging causes progressive remodeling of the left ventricle including cell loss, turnover of the extracellular matrix (ECM), and fibrosis that contribute to impairment of cardiac function. Matrix metalloproteinases (MMPs) are key enzymes responsible for ECM remodeling, and limited data show age-induced alterations in MMP expression. Recently, our lab. demonstrated that 12 weeks of exercise training ameliorates age-induced remodeling in the aging heart. However, there is a stark paucity of data investigating regulation of MMPs by exercise training in the aging heart. We hypothesized that exercise training would attenuate age-induced changes in MMPs in the left ventricle. PURPOSE: Identify the effects of aging and long-term (12 weeks) exercise training on MMP-1, MMP-2, MMP-3, and MMP-9 protein levels in left ventricle of the rat heart. METHODS: Three and 31 mo. old Fischer 344 × Brown Norway F1 hybrid rats were randomly assigned to young sedentary (YS), young exercise (YE), old sedentary (OS), or old exercise (OE) groups. Exercise training groups ran on a treadmill at 20 m/min (young) or 10 m/min (old), 18% grade, 45 min/day, 5 day/wk for 12 wks. Following training, hearts were extracted in young (6 mo) and old (34 mo) rats and frozen in liquid nitrogen. Pro- and active levels of MMP-1, MMP-2, MMP-3, and MMP-9 were measured in the soluble fractions using Western immunoblot analysis. RESULTS: Pro and active protein levels for MMP-1 and MMP-9 were not altered by aging or exercise training. Active MMP-2 levels significantly decreased (−38%) with aging, but there were no training effects on pro/active MMP-2 levels in old groups. Pro-MMP-3 levels were significantly elevated (+199%) with aging, but an increased trend (+30%, p=0.093) existed in OE compared with OS. CONCLUSION: These data demonstrate that aging significantly decreased active MMP-2 protein levels and increased pro-MMP-3 protein levels, whereas exercise training elevated pro-MMP3 protein levels in the old group. Our findings indicate a differential regulation of MMPs with aging and exercise training in the soluble fractions of heart.

Ageing and exercise training alter adrenergic vasomotor responses of rat skeletal muscle arterioles

Ageing is associated with increased leg vascular resistance and reductions in leg blood flow during rest and exercise, potentially predisposing older adults to a host of functional and cardiovascular complications. The purpose of these studies was to examine the effects and possible mechanisms of ageing and exercise training on arteriolar adrenergic vasoreactivity. Young and old male Fischer 344 rats were divided into young sedentary (YS), old sedentary (OS), young exercise-trained (YT) or old exercise-trained (OT) groups, where training consisted of chronic treadmill exercise. Isolated soleus (SOL) and gastrocnemius (GAS) muscle arterioles were studied in vitro. Responses to noradrenaline in endothelium-intact and endothelium-denuded arterioles, as well as during nitric oxide synthase (NOS) inhibition were determined. Vasodilator responses to isoproterenol and forskolin were also determined. Noradrenaline-mediated vasoconstriction was increased in SOL arterioles with ageing, and exercise training in old rats attenuated alpha-adrenergic vasoconstriction in arterioles from both muscle types. Removal of the endothelium and NOS inhibition eliminated these ageing and training effects. Isoproterenol-mediated vasodilatation was impaired with ageing in SOL and GAS arterioles, and exercise training had little effect on this response. Forskolin-induced vasodilatation was not affected by age. The data demonstrate that ageing augments alpha-adrenergic vasoconstriction while exercise training attenuates this response, and both of these alterations are mediated through an endothelial alpha-receptor-NOS-signalling pathway. In contrast, ageing diminishes beta-receptor-mediated vasodilatation, but this impairment is specific to the smooth muscle. These studies indicate that alpha- and beta-adrenergic mechanisms may serve to increase systemic vascular resistance with ageing, and that the effects of exercise training on adrenergic vasomotor properties could contribute to the beneficial effects of exercise on cardiovascular disease.

Effects of Exercise Training on Skeletal Muscle Vascular Geometry in Young and Old Rats

With aging, there is a reduction in the number of feed arteries perforating the gastrocnemius muscle likely resulting from a reduction in spontaneous physical activity in old rats. We tested the hypothesis that exercise training would ameliorate age-related differences in vascular geometry in skeletal muscle. METHODS: Young and old male Fischer 344 rats were divided into young sedentary (YS), old sedentary (OS), young exercise-trained (YT) or old exercise-trained (OT) groups, where training consisted of 10-12 weeks of treadmill exercise. At the end of the training period, all feed arteries perforating the gastrocnemius muscle were isolated, cannulated and maximally dilated for measurement of luminal diameters. RESULTS: In young rats with exercise training there was a significant increase in the number of feed arteries perforating the gastrocnemius muscle (YS, 8.9±0.1 vs. YT, 10.3±0.2 arteries, p<0.05), whereas exercise training did not affect the number of feed arteries in the aged animals (OS, 7.6±0.2; OT, 7.8±0.2 arteries). However, in old animals there was an increased average luminal cross-sectional area (CSA) in feed arteries with exercise training. DISCUSSION: Contrary to our hypothesis, with exercise training there was no apparent increase in the number of feed-arteries perforating the gastrocnemius muscle in old animals. The increased CSA of the feed arteries in old exercise trained animals suggests a structural enlargement of luminal diameters in this group may be a compensatory mechanism to augment blood flow to the muscle. However, the greater number of feed-arteries in young-trained muscle may allow a more precise matching of blood-flow to muscle O2 uptake. Supported by NASA grant NCC2-1166 and NIH F32 AG25622.