Cardioprotective effects of exercise training on myofilament calcium activation in ovariectomized rats.

The risks associated with hormone replacement therapy, especially cardiac diseases in postmenopausal women, have prompted extensive studies for other preventive or therapeutic alternatives. We investigated the cardioprotective effects of exercise training on the changes in cardiac myofilament Ca2+ activation in 10-wk-old ovariectomized rats. The exercise groups were subjected to a 9-wk running program on a motor-driven treadmill 1 wk after surgery. The relationship between pCa (-log molar free Ca2+ concentration) and myofibrillar MgATPase activity of exercise-sham myofibrils or exercise-ovariectomized myofibrils was the same and could not be distinguished from that of sedentary-sham control hearts. In contrast, a significant suppression in maximum MgATPase activity and a leftward shift of pCa50 (half-maximally activating pCa) in the pCa-ATPase activity relationship were detected in sedentary-ovariectomized rats. Exercise training also prevented the shift in myosin heavy chain (MHC) isoforms toward beta-MHC in ovariectomized hearts. The upregulation of beta1-adrenergic receptors in the left ventricular membranes of ovariectomized rat hearts, as measured by receptor binding and immunoblot analyses, was no longer observed in exercise-ovariectomized hearts. Immunoblot analyses of heat shock protein (HSP) 72, an inducible form of HSP70, demonstrated a significant downregulation in ovariectomized hearts. Exercise training in ovariectomized rats completely reversed the expression of HSP72 to the same level as sham controls. Our results clearly indicate the cardioprotective effects of exercise training on changes in cardiac myofilament Ca2+ activation in ovariectomized rats. Alterations in expression of beta1-adrenergic receptors and HSP72 may, in part, play a mechanistic role in the cardioprotective effects.     

Metabolic effects of physical training in ovariectomized and hyperestrogenic rats

This study was undertaken to evaluate theeffects of regular endurance-type exercise on glucose tolerance andglucose-stimulated insulin response (GSIR) in ovariectomized (OVX) ratswith and without estrogen replacement. To do that, OVX Sprague-Dawleyrats were compared with an OVX estradiol-treated group (OVXE2) and asham-operated (Sham) group. Each of these groups was subdivided into asedentary and a treadmill-trained (8 wk) group. Intravenous glucosetolerance tests (0.5 g/kg) were conducted in all rats 48 h afterthe last training session. Plasma levels of 17-estradiol and theuterus weight were significantly (P < 0.05) lower inOVX compared with results in Sham and significantly (P < 0.01) higher in OVXE2 (hyperestrogenic) compared with results inSham. Body weights were significantly (P < 0.01)different among groups, in the following decreasing order: OVX, Sham,and OVXE2. The average daily food intake was significantly(P < 0.01) increased in OVX rats compared with Sham,whereas estradiol treatment diminished this effect (P < 0.01). Exercise training was found to alter none of theabove-mentioned variables in all three experimental conditions. Although the mean integrated area under the glucose and insulin curveswas not affected by OVX, training induced a significant (P < 0.01) reduction in the mean integrated area underthe insulin curve in all three experimental conditions. It is concludedthat the positive effects of physical training on improving GSIR in OVXand hyperestrogenic animals are similar to what has been found in Sham.

     

Effects of exercise training on brown adipose tissue thermogenesis in ovariectomized obese rats

The effect of exercise training on brown adipose tissue (BAT) thermogenesis was studied by measuring cytochrome oxidase activity, as a marker of mitochondrial abundance, mitochondrial guanosine-5'-diphosphate (GDP) binding, as an indicator of thermogenic activity and oxygen consumption in BAT in ovariectomized (OVX) obese rats and sham-operated rats. Six-week exercise training significantly suppressed body weight gain in OVX rats to the level of sedentary control rats, although food intake in exercise trained OVX rats increased more than in the sedentary OVX rats. Exercise training increased cytochrome oxidase activity, mitochondrial GDP binding and oxygen consumption in BAT in OVX rats, which were reduced in a sedentary condition, as well as in the control rats. These results suggest that exercise training potentiates BAT thermogenesis, which may contribute to the reduction of body weight in OVX obese rats.     

Effect of exercise training on cardiac oxytocin and natriuretic peptide systems in ovariectomized rats

Exercise training results in cardiovascular and metabolic adaptations that may be beneficial in menopausal women by reducing blood pressure, insulin resistance, and cholesterol level. The adaptation of the cardiac hormonal systems oxytocin (OT), natriuretic peptides (NPs), and nitric oxide synthase (NOS) in response to exercise training was investigated in intact and ovariectomized (OVX) rats. Ovariectomy significantly augmented body weight (BW), left ventricle (LV) mass, and intra-abdominal fat pad weight and decreased the expression of oxytocin receptor (OTR), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and guanylyl cyclase-A (GC-A), in the right atrium (RA) and LV, indicating estrogenic control of these genes. These effects of ovariectomy were counteracted by 8-wk-long exercise training which decreased fat pad weight (33.4 +/- 2.3 to 23.4 +/- 3.1 g, n = 8, P < 0.05), plasma free fatty acids (0.124 +/- 0.033 to 0.057 +/- 0.010 mM, n = 8, P < 0.01), and plasma triacylglycerol (0.978 +/- 0.174 to 0.588 +/- 0.115 mM, n = 8, P < 0.05). Chronic exercise tended to decrease BW and stimulated ANP (4- to 5-fold) and OTR gene expression in the LV and RA and BNP and inducible NOS (iNOS) mRNA in the LV. In sham-operated rats, exercise augmented ANP expression in the RA, downregulated GC-A mRNA in the LV and RA, but increased its expression threefold in the RA of OVX animals. Endothelial NOS and iNOS expression was enhanced in the left atrium of sham-operated rats. Altogether, these data indicate that in OVX animals, chronic exercise significantly enhances cardiac OT, NPs, and NOS, thus implicating all three hormonal systems in the beneficial effects of exercise training.     

Effects of exercise training on cardiac function, gene expression, and apoptosis in rats

This study determined the effects of exercise training on cardiac function, gene expression, and apoptosis. Rats exposed to a regimen of treadmill exercise for 13 wk had a significant increase in cardiac index and stroke volume index and a concomitant decrease in systemic vascular resistance compared with both age-matched and body weight-matched sedentary controls in the conscious state at rest. In exercise-trained animals, there was no change in the expression of several marker genes known to be associated with pathological cardiac adaptation, including atrial natriuretic factor, beta-myosin heavy chain, alpha-skeletal and smooth muscle actins, and collagens I and III. Exercise training, however, produced a significant induction of alpha-myosin heavy chain, which was not observed in rats with myocardial infarction. No histological features of cardiac apoptosis were observed in the treadmill-trained rats. In contrast, apoptotic myocytes were detected in animals with myocardial infarction. In summary, exercise training improves cardiac function without evidence of cardiac apoptosis and produces a pattern of cardiac gene expression distinct from pathological cardiac adaptation.     

Metabolic effects of estrogen substitution in combination with targeted exercise training on the therapy of obesity in ovariectomized Wistar rats

Postmenopausal women tend to have a higher risk in developing obesity and thus metabolic syndrome. Recently we could demonstrate that physical activity and estrogen replacement are effective strategies to prevent the development of nutritional induced obesity in an animal model. The aim of this study was to determine the combined effects of estrogen treatment and exercise training on already established obesity. Therefore ovariectomized (OVX) and sham-operated (SHAM) female Wistar rats were exposed to a high fat diet for ten months. After this induction period obese SHAM and OVX rats either remained sedentary or performed treadmill training for six weeks. In addition OVX rats were treated with 17β-Estradiol (E(2)) alone, or in combination with training. Before and after intervention effects on lipid and glucose metabolism were investigated. Training resulted in SHAM and OVX rats in a significant decrease of body weight, subcutaneous and visceral body fat, size of adipocytes and the serum levels of leptin, cholesterol, low-density lipoprotein and triglycerides. In OVX animals E(2) treatment resulted in similar effects. Often the combination of E(2) treatment and training was most effective. Analysis of the respiratory quotient indicates that SHAM animals had a better fat burning capacity than OVX rats. There was a tendency that training in SHAM animals and E(2) treatment in OVX animals could improve this capacity. Analysis of glucose metabolism revealed that obese SHAM animals had higher glucose tolerance than OVX animals. Training improved glucose tolerance in SHAM and OVX rats, E(2) treatment in OVX rats. The combination of both was most effective. Our results indicate that even after a short intervention period of six weeks E(2) treatment and exercise training improve parameters related to lipid as well as glucose metabolism and energy expenditure in a model of already established obesity. In conclusion a combination of hormone replacement therapy and exercise training could be a very effective strategy to encourage the therapy of diet-induced obesity and its metabolic consequences in postmenopausal women.     

The interaction effects of aerobic exercise training and vitamin D supplementation on plasma lipid profiles and insulin resistance in ovariectomized rats

Purpose

The purpose of this study was to determine the interaction effects of aerobic exercise training and vitamin D supplementation on indices of obesity and plasma lipid profiles in ovariectomized (OVX) rats.

Methods

Forty female Wistar rats were divided into 5 groups: aerobic training (3 days/week for 8 weeks; AT; n = 8), aerobic training and vitamin D supplementation (OVX + AT + Vit D; n = 8), vitamin D supplementation (OVX + Vit D; n = 8), ovariectomized control (OVX + C, n = 8) and SHAM (n = 8). After blood sampling, visceral fat was taken from the abdominal cavity and weighed immediately. Data was statistically analyzed by One-way ANOVA and Repeated measure ANOVA tests with a 0.05 significance level.

Results

Body weight, visceral fat, BMI and food intake decreased significantly in OVX + AT + Vit D (P < 0.001); whereas these variables increased significantly in OVX + C (P < 0.001) and SHAM (P < 0.023) groups. At the end of two-months of follow-up, we observed significant differences in TC, TG, HDL-C, LDL-C, glucose, insulin, and HOMA-IR in all groups.

Conclusion

It seems that aerobic training with vitamin D, due to the involvement of muscle mass and exposure to dynamic pressure on the bones and muscles, increased energy expenditure, stimulated insulin exudation and glucose homeostasis, decreased insulin resistance and improved the lipid profile in ovariectomized rats.     

Growth factors and glucose homeostasis in diabetic rats: effects of exercise training

To investigate the alterations of glucose homeostasis and variables of the insulin‐like growth factor‐1 (IGF‐1) growth system in sedentary and trained diabetic (TD) rats, Wistar rats were divided into sedentary control (SC), trained control (TC), sedentary diabetic (SD), and TD groups. Diabetes was induced by Alloxan (35 mg kg^?1 b.w.). Training program consisted of swimming 5 days week^?1, 1 h day^?1, during 8 weeks. Rats were sacrificed and blood was collected for determinations of serum glucose, insulin, growth hormone (GH), IGF‐1, and IGF binding protein‐3 (IGFBP‐3). Muscle and liver were removed to evaluate glycogen content. Cerebellum was extracted to determinate IGF‐1 content. Diabetes decreased serum GH, IGF‐1, IGFBP‐3, liver glycogen, and cerebellum IGF‐1 peptide content in baseline condition. Physical training recovered liver glycogen and increased serum and cerebellum IGF‐1 peptide in diabetic rats. Physical training induces important metabolic and hormonal alterations that are associated with an improvement in glucose homeostasis and serum and cerebellum IGF‐1 concentrations. Copyright © 2009 John Wiley & Sons, Ltd.     

Suppressive effects of genistein dosage and resistance exercise on bone loss in ovariectomized rats.

This study was designed to determine whether combined treatments with genistein dosage and moderate resistance exercise would exhibit synergistically preventive effects on bone loss following the onset of menopause. Forty-one 12 wk-old female SD rats were assigned to five groups: 1) Sham operated (Sham); 2) ovariectomized (OVX-Cont); 3) OVX received genistein (OVX-GEN); 4) OVX exercised (OVX-EXE); and 5) OVX treated with both genistein and exercise (OVX-GEN-EXE). All rats were fed a low Ca (0.1%) diet ad libitum. Daily genistein dosage was 12 mg/kg body weight. Exercising rats took 40 sets of 1-min run interspersed with 1-min rest with a 100 g weight on the back on an uphill treadmill at 20 m/min. The experimental duration consisted of the adaptation and treatment periods of 4 weeks each. Uterine weight in OVX-Cont, OVX-GEN, OVX-EXE and OVX-GEN-EXE decreased to about 15% of that in Sham (p < 0.001). The femoral BMD (mg/cm2; mean +/- SE), assessed by DEXA (Lunar), of OVX-Cont was significantly lowered to 206 +/- 5 by -9%, as compared to 226 +/- 2 of Sham (p < 0.001). The BMD of OVX-GEN, OVX-EXE and OVX-GEN-EXE were 217 +/- 2, 217 +/- 2 and 222 +/- 2, respectively, and genistein dosage and resistance exercise equally increased the BMD of OVX rats by 5% (p < 0.01). Combined treatment of genistein and exercise more successfully recovered their decreased BMD by 8% (p < 0.001). BMD of the fourth lumbar vertebrae in OVX-Cont was declined to 191 +/- 7 by -15%, as compared to 225 +/- 4 in Sham (p < 0.001). OVX-EXE and OVX-GEN-EXE gained the BMD by 6% to 205 +/- 4 and 203 +/- 3, respectively, as compared to that of OVX-Cont (p < 0.01). These results suggest the possibility that the combined treatment of genistein dosage and resistance exercise have more beneficial effects by acting rather independently than their separate trials on the prevention of ovx-induced bone loss in femurs.     

Collagen gene expression in rat left ventricle: interactive effect of age and exercise training.

Whether or not exercise training of sufficient intensity and duration to produce left ventricle (LV) hypertrophy also regulates deposition of interstitial collagen and cross-linking at the pretranslational level is unknown. Therefore, the effects of exercise training on gene expression for the two principal fibrillar collagens in LV, types I and III, were assessed in young adult (5 mo), middle-aged (15 mo), and old (26 mo) rats. We also evaluated the potential interaction of changes in mRNA for these procollagens with alterations in LV extracellular matrix characteristics by simultaneously measuring collagen concentration (hydroxyproline) and extent of mature collagen cross-linking (hydroxylysylpyridinoline, HP). Ten weeks of treadmill running resulted in LV hypertrophy and an increased maximal oxygen uptake in all three age groups of trained rats compared with sedentary controls. Percent collagen in rat LV almost doubled (P < 0.0001) from 5 to 26 mo of age, an increase unaffected by exercise training. With aging, a significant decline in expression of mRNAs for both collagen type I (P < 0.005) and type III (P < 0.001) was observed in LV free wall (LVF) but not septum (LVS). Training prevented this decline in LVF mRNAs for the two principal fibrillar collagens in middle-aged rats whereas it attenuated the decline in senescent animals. HP concentration increased significantly with aging in both LVF (P < 0.005) and LVS (P < 0.01). Training modulated this effect, but again only in LVF, so that HP was significantly lower (P < 0.05) in this region of the LV in old trained rats compared with sedentary counterparts. We conclude that exercise training modulates the effects of aging on collagen gene mRNAs and HP cross-linking regionally within the LV.     

The effects of ovarian hormones on glucose and fatty acid oxidation during exercise in female ovariectomized rats

The effects of ovarian hormones on glucose and fatty acid oxidation during exercise were investigated in adult female ovariectomized rats. Rats subdivided into 3 groups received intraperitoneal injections of hormones or sesame oil for 8 days. Estrogen (E) treated rats received 17-beta estradiol in daily doses of 2 micrograms. Estrogen and progesterone treated rats (EP) received 17-beta estradiol in daily doses of 2 micrograms and 2 mg, respectively. Control rats (S) received sesame oil alone. After an overnight fast, rats ran at the speed of 25 m.min-1 for 60 min. [U-14C]glucose or [1-14C]palmitate was injected into rats at 5 min of exercise and before 10 min of exercise, respectively. Expired 14CO2 was collected using bottomless chamber on a treadmill belt. No significant differences were found in mean blood glucose, lactate and plasma free fatty acid concentrations after the exercise. Until the end of the exercise 34.7 +/- 2.6 (E, n = 5), 40.8 +/- 2.9 (EP, n = 5) and 43.7 +/- 3.5% (S, n = 6) (mean +/- SE) of 14C which was injected as 14C-glucose was recovered as 14CO2. During 60 min of the exercise 27.5 +/- 1.0 (E, n = 7), 19.8 +/- 2.7 (EP, n = 6) and 25.0 +/- 1.9% (S, n = 6) of 14C which was injected as 14C-palmitate was recovered as 14CO2. A significant difference was found in this rate between E and EP (P less than 0.05). It was concluded that estrogen treatment stimulated fatty acid oxidation compared with the estrogen plus progesterone treatment and tended to inhibit glucose oxidation during prolonged exercise.     

The effects of different exercise modes for preventing endothelial dysfunction of arteries and bone loss in ovariectomized rats

[Purpose]

Several epidemiological studies have demonstrated that there are positive correlations between vascular disorders and bone loss in postmenopausal women. The aim of the present study was to examine the effect of different types of exercise (e.g., climbing and swimming) for preventing endothelial dysfunction of arteries and bone loss in ovariectomized rats.

[Methods]

Twenty Sprague-Dawley female rats were randomly divided into three groups: ovariectomy (OVX) plus treatment with vitamin D₃ and nicotine (VDN) (control rats [Con], n = 7), which is an animal model for endothelial dysfunction and bone loss; voluntary climbing resistance exercise with OVX plus VDN (climbing rats [Clim], n = 6), and swimming exercise with OVX plus VDN (swimming rats [Swim], n = 7). The period of exercise training was 8 weeks.

[Results]

The endothelin-1 (ET-1) protein levels were significantly lower in the Clim and Swim groups than in the Con. The endothelial nitric oxide synthase protein levels were significantly higher in the Swim group than in the Con, but they did not differ between the Clim and Con groups. The cortical bone mineral density in the tibia and breaking energy of the femur were significantly higher in the Clim group than in the Con, but this positive effect was not seen in the Swim group.

[Conclusion]

Voluntary climbing exercise decreased arterial ET-1 protein levels and prevented bone loss in a postmenopause-model rat combining OVX and VDN. Conversely, swimming suppressed endothelial dysfunction of the arteries but did not prevent bone loss. Thus, the type of exercise should be cautiously chosen for enhancing vascular function and bone status, especially in females after menopause.     

Anti-hypertensive effects of Rosuvastatin are associated with decreased inflammation and oxidative stress markers in hypertensive rats

Among their pleiotropic effects, statins exert antioxidant and anti-inflammatory properties. The aim of this study was to evaluate in normotensive (WKY) and in spontaneously hypertensive rats (SHR) the effect of rosuvastatin (ROSU) treatment on (1) plasma inflammation markers and endogenous NO synthase inhibitor (ADMA) levels, (2) reactive oxygen species (ROS) generated by circulating leukocytes and (3) vascular oxidative stress and tissue inflammation markers. Plasma cytokines were higher in SHR than in WKY, except for IL-4, which was lower in SHR than in WKY. SHR monocytes exhibited higher production of ROS than did WKY monocytes. In the experimental conditions, ROSU did not modify plasma cholesterol levels in SHR but attenuated the increase in systolic blood pressure. In SHR only, ROSU lessened pro-inflammatory cytokines and ADMA levels, increased IL-4 and reduced ROS production in circulating monocytes. These results demonstrate the beneficial effects of ROSU in SHR, independently of any lowering of cholesterol levels.     

Anti-hypertensive effects of Rosuvastatin are associated with decreased inflammation and oxidative stress markers in hypertensive rats

Among their pleiotropic effects, statins exert antioxidant and anti-inflammatory properties. The aim of this study was to evaluate in normotensive (WKY) and in spontaneously hypertensive rats (SHR) the effect of rosuvastatin (ROSU) treatment on (1) plasma inflammation markers and endogenous NO synthase inhibitor (ADMA) levels, (2) reactive oxygen species (ROS) generated by circulating leukocytes and (3) vascular oxidative stress and tissue inflammation markers. Plasma cytokines were higher in SHR than in WKY, except for IL-4, which was lower in SHR than in WKY. SHR monocytes exhibited higher production of ROS than did WKY monocytes. In the experimental conditions, ROSU did not modify plasma cholesterol levels in SHR but attenuated the increase in systolic blood pressure. In SHR only, ROSU lessened pro-inflammatory cytokines and ADMA levels, increased IL-4 and reduced ROS production in circulating monocytes. These results demonstrate the beneficial effects of ROSU in SHR, independently of any lowering of cholesterol levels.     

Effects of gradual coronary artery occlusion and exercise training on gene expression in swine heart

Gradual occlusion (O) of the swine left circumflex coronary artery (LCX) with an ameroid occluder results in complete O within 3 weeks, collateral vessel development, and compensatory hypertrophy. The purpose of this investigation was to determine the independent and combined effects of O and exercise training (E) on gene expression in the swine heart. Adult Yucatan miniature swine were assigned to one of the following groups (n = 6–9/group): sedentary control (S), exercise-trained (E), sedentary swine subjected to LCX occlusion (SO), and exercise-trained swine with LCX occlusion (EO). Exercise consisted of progressive treadmill running conducted 5 d/wk for 16 weeks. Gene expression was studied in myocardium isolated from the collateral-dependent left ventricle free wall (LV) and the collateral-independent septum (SEP) by RNA blotting. E and O each stimulated cardiac hypertrophy independently (p < 0.001) with no interaction. O but not E increased atrial natriuretic factor expression in the LV, but not in the SEP. E decreased the expression of β-myosin heavy chain in the LV, but not in the SEP. E retarded the expression of collagen III mRNA in SEP; but not in the LV. Exercise training and coronary artery occlusion each stimulate cardiac hypertrophy independently and induce different patterns of gene expression.     

Effect of short-term exercise training on angiogenic growth factor gene responses in rats.

We investigated whether 1) 5 days of exercise training would reduce the acute exercise-induced increase in skeletal muscle growth factor gene expression; and 2) reductions in the increase in growth factor gene expression in response to short-term exercise training would be coincident with increases in skeletal muscle oxidative potential. Female Wistar rats were used. Six groups (rest; exercise for 1-5 consecutive days) were used to measure the growth factor response through the early phases of an exercise training program. Vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and basic fibroblast growth factor (bFGF) mRNA were analyzed from the left gastrocnemius by quantitative Northern blot. Citrate synthase activity was analyzed from the right gastrocnemius. VEGF and TGF-beta1 mRNA increased after each of 5 days of exercise training, whereas exercise on any day did not increase bFGF mRNA. On day 1, the VEGF mRNA response was significantly greater than on days 2-5. However, the reduced increase in VEGF mRNA observed on days 2-5 was not coincident with increases in citrate synthase activity. These findings suggest that, in skeletal muscle, 1) VEGF and TGF-beta1 mRNA are increased through 5 days of exercise training and 2) the reduced exercise-induced increase in VEGF mRNA responses on days 2-5 does not result from increases in oxidative potential.     

Microarray expression analysis of effects of exercise training: increase in atrial MLC-1 in rat ventricles

Previous studies have shown that endurance exercise training increases myocardial contractility. We have previously described training-induced alterations in myocardial contractile function at the cellular level, including an increase in the Ca(2+) sensitivity of tension. To determine the molecular mechanism(s) of these changes, oligonucleotide microarrays were used to analyze the gene expression profile in ventricles from endurance-trained rats. We used an 11-wk treadmill training protocol that we have previously shown results in increased contractility in cardiac myocytes. After the training, the hearts were removed and RNA was isolated from the ventricles of nine trained and nine control rats. With the use of an Affymetrix Rat Genome U34A Array, we detected altered expression of 27 genes. Several genes previously found to have increased expression in hypertrophied myocardium, such as atrial natriuretic factor and skeletal alpha-actin, were decreased with training in this study. From the standpoint of altered contractile performance, the most significant finding was an increase in the expression of atrial myosin light chain 1 (aMLC-1) in the trained ventricular tissue. We confirmed microarray results for aMLC-1 using RT-PCR and also confirmed a training-induced increase in aMLC-1 protein using two-dimensional gel electrophoresis. aMLC-1 content has been previously shown to be increased in human cardiac hypertrophy and has been associated with increased Ca(2+) sensitivity of tension and increased power output. These results suggest that increased expression of aMLC-1 in response to training may be responsible, at least in part, for previously observed training-induced enhancement of contractile function.