Swimming eliminates the weight gain and abdominal fat associated with ovariectomy in the retired breeder rat despite high-fat diet selection

Effects of a flotation vest and water flow rate on limb kinematics of Siberian Huskies swimming against a current

OBJECTIVE

To evaluate the effects of a flotation vest (FV) and water flow rate (WFR) on limb kinematics of dogs swimming against a current.

ANIMALS

7 (1 male and 6 female) healthy adult Siberian Huskies.

PROCEDURES

Dogs were habituated to swim with and without an FV beside an investigator in a continuous-flow pool against WFRs up to 2.9 km/h. During each of 4 experimental sessions in a repeated-measures study, markers were wrapped around the right carpus and tarsus, and a video was recorded while each dog swam with or without an FV for about 2 minutes at each of 7 WFRs between 0 and 2.9 km/h when the WFR was incrementally decreased or increased. Motion tracking software was used to measure stroke excursion and frequency.

RESULTS

Stroke excursion varied more than frequency among all dogs and in response to changes in experimental conditions. The male dog and 1 female dog were unable to complete the study. For the remaining 5 dogs across all experimental conditions, mean tarsus excursion was 30% that of the carpus. Mean total excursion (sum of the excursion-frequency products for the carpus and tarsus) decreased when an FV was worn and increased with WFR by 69% and 19% when WFR was incrementally increased and decreased, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs, range of motion during swimming was greater for the carpus than tarsus, when an FV was not worn, and increased more with WFR when WFR was incrementally increased. Those factors should be considered during swimming-based rehabilitation.

Effects of six weeks of resistance-endurance training on microRNA-29 expression in the heart of ovariectomised rats

INTRODUCTION

Heart disease risk rises with age. However, women's symptoms become more pronounced following the onset of menopause. The aim of the present study was to evaluate the effects of six weeks of combined resistance-endurance (RE) training on microRNA-29 expression in the heart of ovariectomised rats.

MATERIAL AND METHODS

Thirty female Wistar rats were divided into three groups: 1) sham (SHAM); 2) ovariectomy (OVX); and 3) OVX with RE training (OVX + RE). The effects of these treatments on cardiac microRNA-29 expression were measured using real-time PCR. Data were analysed using a 2 × 3 ANOVA and Tukey post-hoc comparisons and presented as mean ±SEM.

RESULTS

Ovariectomy resulted in a significant down-regulation in the heart microRNA-29 gene expression of OVX (0.265 ±0.031 fold changes), OVX + RE (0.699 ±0.038 fold changes) in animals vs. sham animals (1 ±0 fold changes; all, p < 0.05) following six weeks of treatment. However, microRNA-29 expression in the OVX + RE group was significantly greater than in the OVX group (p < 0.05).

CONCLUSIONS

Our findings suggest that the six weeks of regular RE training attenuate the reduction in heart muscle microRNA-29 expression observed in ovariectomised rates. If our findings carry over to humans, such an exercise regimen could be beneficial to the cardiovascular disease risk in women during menopause.

Effect of combined endurance-resistance training and soy extract supplementation on expression of eNOS gene in ovariectomized rats

Introduction

Menopause is an independent risk factor for cardiovascular disease (CVD). Physical exercise and soybean diets have been suggested to reduce the risk of CVD in postmenopausal women. The purpose of this study was to investigate the effects of combined resistance and endurance (RE) training and soy extract (SOY) supplementation, both known to improve endothelial function, on expression of the eNOS gene in the heart of ovariectomized (OVX) rats.

Material and methods

Fifty female Wistar rats were divided into five groups: 1) sham (SHAM); 2) ovariectomy (OVX); 3) ovariectomy with soy extract supplementation (OVX + SOY); 4) OVX with RE training (OVX + RE); 5) and ovariectomy plus RE training with soy extract supplementation (OVX + RE + SOY). RE training and soy extract supplementation were administered alone or in combination for 6 weeks. The effects of these treatments on cardiac eNOS expression were measured using real-time PCR.

Results

Ovariectomy down-regulated cardiac eNOS gene expression; however, 6 weeks of SOY treatment or RE training reversed this effect (p ≤ 0.05). The combination of SOY plus RE was greater than RE or SOY alone in reversing estrogen-deficiency-caused eNOS down-regulation (p ≤ 0.05).

Conclusions

Our data suggest that the combinatory regimen of soy extract supplementation and regular RE training may be more beneficial to cardiovascular disease risk in a menopause rat model than either exercise or soy supplementation alone.

Aerobic Exercise Training Prevents the Onset of Endothelial Dysfunction via Increased Nitric Oxide Bioavailability and Reduced Reactive Oxygen Species in an Experimental Model of Menopause

OBJECTIVE

Previous studies have shown that estrogen deficiency, arising in postmenopause, promotes endothelial dysfunction. This study evaluated the effects of aerobic exercise training on endothelial dependent vasodilation of aorta in ovariectomized rats, specifically investigating the role of nitric oxide (NO) and reactive oxygen species (ROS).

METHODS

Female Wistar rats ovariectomized (OVX - n=20) or with intact ovary (SHAM - n=20) remained sedentary (OVX and SHAM) or performed aerobic exercise training on a treadmill 5 times a week for a period of 8 weeks (OVX-TRA and SHAM-TRA). In the thoracic aorta the endothelium-dependent and -independent vasodilation was assessed by acetylcholine (ACh) and sodium nitroprusside (SNP), respectively. Certain aortic rings were incubated with L-NAME to assess the NO modulation on the ACh-induced vasodilation. The fluorescence to dihydroethidium in aortic slices and plasma nitrite/nitrate concentrations were measured to evaluate ROS and NO bioavailability, respectively.

RESULTS

ACh-induced vasodilation was reduced in OVX rats as compared SHAM (Rmax: SHAM: 86±3.3 vs. OVX: 57±3.0%, p<0.01). Training prevented this response in OVX-TRA (Rmax: OVX-TRA: 88±2.0%, p<0.01), while did not change it in SHAM-TRA (Rmax: SHAM-TRA: 80±2.2%, p<0.01). The L-NAME incubation abolished the differences in ACh-induced relaxation among groups. SNP-induced vasodilation was not different among groups. OVX reduced nitrite/nitrate plasma concentrations and increased ROS in aortic slices, training as effective to restore these parameters to the SHAM levels.

CONCLUSIONS

Exercise training, even in estrogen deficiency conditions, is able to improve endothelial dependent vasodilation in rat aorta via enhanced NO bioavailability and reduced ROS levels.

Influence of cholestatic jaundice on the weight variance in an experimental model

OBJECTIVE

To evaluate the influence of cholestatic jaundice in weight variation.

METHODS

We used 64 adult rats divided into six groups: F1 (n = 6): normal females; F2 (n = 6): laparotomy females; F3 (n = 20): jaundiced females; M1 (n = 6): normal males; M2 (n = 6): laparotomy males; M3 (n = 20): jaundiced males. Jaundice was obtained by ligation and section of the biliopancreatic duct. The animal weights were recorded weekly for seven weeks. On the 14th day of the experiment, bilirubin and gonadal hormones were assessed. After the seventh week a histological study of the liver was performed.

RESULTS

The animals in groups F3 and M3 showed elevated bilirubin and decreased body mass when compared to the other groups. The weight differences were significant from the fourth week on amongst females and from the fifth in males. In Jaundiced animals there was increased estradiol and decreased progesterone and testosterone. Perivenular septa and periportal fibrosis, cholangitis and bile duct hyperplasia occurred in the liver of jaundiced rats. No animal showed cirrhosis.

CONCLUSION

There was decrease in murine body weight in the presence of cholestatic jaundice in both genders.

Adult Female Rats Defend “Appropriate” Energy Intake after Adaptation to Dietary Energy

OBJECTIVE

To determine if adult female rats adapt to lower and higher dietary energy density.

RESEARCH METHODS AND PROCEDURES

Study 1 compared high-fat (56%), high-energy density (HD) (21.6 kJ/g) and high-fat (56%), low-energy density (LD) (16.0 kJ/g) diets before surgery (two groups, 2 weeks, n = 16) and after surgery [ovariectomy (O) Sham (S); 2 x 2 factorial, n = 8; 6 weeks]. The second study (no surgery) compared high-fat (60.0%), high-energy (22.0 kJ/g) and low-fat (10.0%), low-energy (15.1 kJ/g) diets (n = 8).

RESULTS

In study 1, food intake was similar for the first 2 weeks, but rats on the LD diet consumed less energy, gained less weight, and had lower nonfasted serum leptin (all p < 0.0001) than rats on the HD diet. After surgery, rats on the LD and HD diets had similar weight gain, but rats on the LD diet consumed more food (p < 0.0001) and less energy (p < 0.009). O rats consumed more food and gained more weight (p < 0.0001) than S rats. Results from study 2 were similar to those from study 1.

DISCUSSION

The results demonstrated that O and S surgery rats and rats with no surgery adjust their food intake to defend a level of energy intake. This defense only occurred after a 2-week adaptation period. The major differences in final body weights and abdominal fat resulted from the initial 2 weeks before adaptation to energy density. Rats fed higher-energy diets seemed to "settle" at a higher level of adiposity, and rats fed lower-energy diets consumed more food to increase energy consumption.

Effects of food pattern change and physical exercise on cafeteria diet-induced obesity in female rats

Obesity affects a large number of people around the world and appears to be the result of changes in food intake, eating habits and physical activity levels. Changes in dietary patterns and physical exercise are therefore strongly recommended to treat obesity and its complications. The present study tested the hypothesis that obesity and metabolic changes produced by a cafeteria diet can be prevented with dietary changes and/or physical exercise. A total of fifty-six female Wistar rats underwent one of five treatments: chow diet; cafeteria diet; cafeteria diet followed by a chow diet; cafeteria diet plus exercise; cafeteria diet followed by a chow diet plus exercise. The duration of the experiment was 34 weeks. The cafeteria diet resulted in higher energy intake, weight gain, increased visceral adipose tissue and liver weight, and insulin resistance. The cafeteria diet followed by the chow diet resulted in energy intake, body weight, visceral adipose tissue and liver weight and insulin sensitivity equal to that of the controls. Exercise increased total energy intake at week 34, but produced no changes in the animals' body weight or adipose tissue mass. However, insulin sensitivity in animals subjected to exercise and the diet was similar to that of the controls. The present study found that exposure to palatable food caused obesity and insulin resistance and a diet change was sufficient to prevent cafeteria diet-induced obesity and to maintain insulin sensitivity at normal levels. In addition, exercise resulted in normal insulin sensitivity in obese rats. These results may help to develop new approaches for the treatment of obesity and type 2 diabetes mellitus.

Combined effects of exercise and soy isoflavone diet on paraoxonase, nitric oxide and aortic apoptosis in ovariectomized rats

Menopause is associated with an increased risk of cardiovascular disease (CVD). Exercise and soy isoflavone diets have been suggested to reduce the risk of CVD in postmenopausal women. We investigated the effects of exercise, or combined exercise and soy isoflavone diet, on plasma lipid profiles, paraoxonase (PON), nitric oxide (NO) and apoptosis in the aorta of ovariectomized (OVX) rats. Thirty-two female Sprague-Dawley rats were divided into four groups: OVX with general diet (OVX-GD), OVX with isoflavone diet (OVX-ISO), OVX-GD with exercise training (OVX-ET) and OVX-ISO with exercise training (OVX-ISO+ET). The experimental rats undertook treadmill training (30 min/day, 4 days/week) and/or were supplied a soy isoflavone diet (added to the experimental diet at 2.39 mg/g protein) for 12 weeks. Body weight and levels of total cholesterol (TC), triglyceride (TG), LDL-cholesterol (LDL-C) increased in the OVX rats and HDL-C decreased. These effects were reduced by exercise and/or soy isoflavone supplementation. PON and NO activities were higher in the OVX-ISO+ET group than in the OVX-GD group. In addition, this group had lower caspase-9 and -3 and higher Bcl-2 expression, and there was less aortic apoptotic cell death. These results suggest that a combination of exercise and a soy isoflavone diet has beneficial effects in terms of protecting against cardiovascular risk factors by controlling lipid profiles and the related enzyme, PON, as well as NO activity and apoptosis of the aorta in OVX rats.

The effects of 20-hydroxyecdysone and 17β-estradiol on the skin of ovariectomized rats

OBJECTIVE

20-hydroxyecdysone has numerous favorable effects on a variety of organs, including the skin, where it improves wound healing. It is devoid of estrogenic and androgenic effects. Therefore, application of 20-hydroxyecdysone might be a new approach to improve skin conditions in postmenopausal women, and this was investigated in ovariectomized (OVX) rats.

METHODS

After ovariectomy, rats received Ecd (18, 57, or 116 mg/animal/day) or 17β-estradiol (E₂)-3-benzoate (60 μg/kg body weight) in food for 12 weeks, and skin samples were evaluated histologically to quantify two dermal layers, the subcutaneous fat and muscle layers.

RESULTS

Epidermal thickness was lowest in the OVX animals, slightly higher in the E₂-treated animals, and significantly higher in the Ecd-treated animals. Dermal thickness was lowest in the intact and E₂-treated animals and highest in the Ecd-treated animals. The subcutaneous fat layer was thickest in the OVX animals, thinner in the intact animals, and intermediate in the Ecd-treated animals. The muscle layer was smallest in the OVX and intact animals and significantly larger in the E₂- and Ecd-treated animals. The number of proliferating cell nuclear antigen antibody-positive cells was lowest in OVX controls and significantly higher in all other groups.

CONCLUSIONS

The Ecd-induced increases in epidermal and dermal thickness are suggestive of functional changes of the skin. The decreased amounts of subcutaneous fat in the E₂- and Ecd-treated animals point to either a fat catabolic or an antianabolic effect. The ovariectomy-induced decrease in subcutaneous musculature was prevented by Ecd but not by E₂. The stimulatory effects of Ecd on epidermal and dermal thickness and the muscle-increasing effects in the skin of OVX rats may indicate functional changes of the skin.

[Body mass regulation by estrogen and physical activity]

Female steroid hormones deficiency leads to a significant increase in body mass, but the possible central and peripheral mechanisms involved in increased food ingestion and fat accumulation in this situation are still unknown. In animal models, the specific lack of estrogen or its action produce progressive body mass gain, clearly demonstrating the possible role of this hormone in overweight after menopause. Obesity and overweight correspond to a relevant human health problem that can lead to premature death. Therefore unraveling the mechanisms underlying body mass gain is of great relevance, as well as the development of strategies to prevent its establishment. Energy balance regulation is associated with the control of body mass, and physical exercise is an important modulator of this homeostatic parameter. However, the influence of physical exercise in mass gain development during estrogen deficiency is controversial and depends on the exercise protocol used. In this study, we intend to review the data on the effects of estrogen deficiency on body mass gain in humans and animal models.

Macronutrient selection in experimental animals

To address the question of how animals choose diets from an array of nutritionally different foods, researchers have designed experiments in which animals are provided with separate sources of the three macronutrients, protein, fat and carbohydrate. These experiments are useful for investigating the neuroanatomical and neurochemical mechanisms involved in food choice, as well as for assessing the effects of changes in physiological status (e.g., pregnancy; lactation and increased energy expenditure) or disease states (e.g., diabetes; and obesity) on nutrient intakes.

Influência da ooforectomia na variação ponderal em ratas jovens e adultas

Para avaliar a influência do tempo de ooforectomia na variação ponderal, foram utilizadas 60 ratas, divididas em dois grupos (30 em cada grupo): Grupo A - jovens; e Grupo B - adultas. Os animais de cada grupo foram subdivididos em três subgrupos: Subgrupo 1 - controle (n= 6); Subgrupo 2 - laparotomia (n= 6); Subgrupo 3 (n= 18) - ooforectomia total bilateral. Os animais foram pesados semanalmente durante 13 semanas e os resultados foram avaliados pelo teste t de Student, com significância para p<0,05. As ratas ooforectomizadas tiveram ganho ponderal maior do que as demais, sendo a diferença significativa a partir da 11ª semana no Grupo A e 9ª semana no Grupo B, persistindo até o fim do experimento. No presente trabalho, a ooforectomia bilateral em ratas relacionou-se com maior ganho ponderal, independente da idade dos animais.