Resistance training suppresses intra-abdominal fatty acid synthesis in ovariectomized rats.

Ovarian hormone loss is associated with a shift in fat distribution to intra-abdomin al adipose tissue (intra-AAT) depots and with lipid metabolism disorders, which predisposes individuals to developing insulin resistance. Resistance training (RT) prevents increases in intra-AAT after ovarian hormone loss. However, the molecular mechanisms underlying these changes remain unclear. We investigated the effects of ovariectomy and RT on gene expression related to lipogenesis and fat oxidation in the intra-AAT of ovariectomized rats. Sprague-Dawley rats (n=6/group) were divided into the groups: sham-sedentary, ovariectomized-sedentary, sham-RT and ovariectomized-RT. RT groups performed a 10-week climbing program on a ladder with progressive overload. Intra-AAT was subjected to morphometric and mRNA analysis. Ovariectomized-sedentary group had larger adipocytes and higher expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), sterol regulatory element-binding protein-1c (SREBP-1c), stearoyl-CoA desaturase-1 (SCD-1), acetyl-CoA carboxylase (ACC), hormone-sensitive lipase (HSL) and lower expression of the oxidative carnitinepalmitoyltransferase-I (CPT-1). RT counteracted OVX-induced increases in PPAR-γ and SCD-1 and decreased SREBP-1c. ACC and HSL were downregulated in ovariectomized-RT compared with the ovariectomized-sedentary group. Ovariectomized-RT group had the highest CPT-1 gene expression. Adipocyte size decreased in ovariectomized-RT group. Results suggest that RT reduces intra-AAT adipocyte size in ovariectomized rats by suppressing intra-AAT fatty acid synthesis and enhancing fatty acid ß-oxidation.

Increased lactate threshold after five weeks of treadmill aerobic training in rats.

The aim of the present study was to analyse the lactate threshold (LT) changes in rats submitted to an aerobic treadmill-training programme. Twenty-five Wistar rats were divided into two groups: a sedentary control group (CG), and a trained group (TG) submitted to an aerobic training during 5 weeks. All the animals were submitted to an incremental treadmill exercise test in order to determine LT. There was an increase in the maximum running speed in the TG (from 32.25 ± 1.27 to 47.75 ± 3.13 m.min-1 - p = 0.001), and running speed at LT (from 26.21 ± 1.15 to 35.30 ± 2.24 m.min-1 - p = 0.004), a part from the reduction in blood lactate at LT. LT can be determined in rats, and aerobic training induced positive oxidative physiological adaptations in the animals.

Effects of long-term periodized resistance training on body composition, leptin, resistin and muscle strength in elderly post-menopausal women.

AIM: Objective of the study was to determine the effects of a periodized resistance training program on body composition, plasmatic levels of leptin and resistin, and muscle strength in elderly post-menopausal women. METHODS: Twenty-three post-menopausal women (age= 63.02±4.42 years; height 1.55±0.06 m; body mass 67.56±2.26 kg) were submitted to 12 months of periodized resistance training twice a week. The training program consisted of 3 sets of 6-14 repetitions maximal (RM). Body composition (DXA), muscle strength (bench press, leg press 45º and arm curl), plasmatic levels of resistin and leptin (ELISA method) were assessed before and after the training program. Paired Student's t test was used for comparison between pre- and post-training values. RESULTS: There was a significant increase in muscle strength and lean body mass; decrease in body mass, body fat percentage and fat mass after 12 months of resistance training, a part from the decrease in leptin and resistin levels. CONCLUSION: Long-term periodized resistance training prevents aging sarcopenia, decreases body fat and systemic markers of inflammation in postmenopausal elderly women.

Acute resistance training affects cell surface markers for apoptosis and migration in CD4⁺ and CD8⁺ lymphocytes.

The purpose of the present study was to examine the acute effects of resistance training (RT) on CD4⁺ and CD8⁺ T lymphocytes apoptosis (annexin V⁺) and migration (CX3CR1). Twelve subjects performed two RT sessions (3 sets of 9 exercises) with 1 min (Hyper-1) and 3 min (Hyper-3) of rest-interval length between sets and exercises. CD4⁺ and CD8⁺ cells count displayed no change following Hyper-1 and Hyper-3. There was an increase in the percentage of CD4⁺ positive for annexin V⁺ and CX3CR1⁺ immediately after and 24 h post Hyper-1. Percentage of CD4⁺ positive for annexin V⁺ increased 2 and 24 h post Hyper-3, and decreased after CXCR1⁺ for the same time-points. There was an increase in CD8⁺ positive for annexin V⁺ and CX3CR1⁺ immediately after, 2 and 24 h post Hyper-1 and Hyper-3, while no differences were found between Hyper-1 and Hyper-3. Acute RT increase the apoptosis and migration of CD4⁺ and CD8⁺ lymphocytes even 24h after exercise, with minimal effects of rest-interval length.

Resistance training and glycogen content in ovariectomized rats.

The aim of the present study was to investigate the effects of resistance training on glycogen content and muscle cross-sectional area (CSA) in ovariectomized rats. Wistar rats were divided into: sedentary; ovariectomized sedentary; resistance trained; and ovariectomized resistance trained. In the 12-week resistance training, the animals climbed a 1.1 m vertical ladder, 3 days per week, with 4-8 climbs. Cardiac, liver and muscle glycogen content was determined. After the 12-week resistance training period there was a higher hepatic and muscle glycogen content in the resistance training group compared with the other groups (p<0.01). CSA was higher in soleus for the resistance trained, ovariectomized resistance trained and sedentary compared with ovariectomized sedentary (p<0.05). Ovariectomy attenuated the increase in liver and muscle glycogen content, while soleus muscle cross-sectional area increased with resistance training, even in ovariectomized rats. Resistance training could be an important exercise to increase muscle function in situations of reduced estrogen and progesterone.

Effects of resistance training on matrix metalloproteinase-2 activity and biomechanical and physical properties of bone in ovariectomized and intact rats.

The purpose of this study was to investigate the influence of resistance training on the activity of matrix metalloproteinase (MMP)-2 and bone biomechanical properties in ovariectomized and intact rats. Forty-eight female rats were divided into two distinct groups, ovariectomized (OVX) and intact (Int), which were subdivided into three similar subgroups: sedentary, acute exercise and chronic exercise. Rats performed a resistance training for 12 weeks in which animals climbed a vertical ladder of 1.1 m with weights attached to their tails. Sessions were performed with an interval of 3, 4-9 and 8-12 days scaled dynamic movements of climbing. Biomechanical and physical analyses were performed using a universal testing machine, and MMP-2 activity analysis by zymography. Bone density (BD), mineral density (MD), maximum load and fracture load was reduced in sedentary and acute exercise OVX groups compared with the sedentary intact group (P<0.05); in contrast, chronically trained groups (OVX and Int) showed a significant increase in BD, MD and fracture load compared with all the other groups. MMP-2 activity in chronically trained groups also showed a significant increase, while the sedentary OVX group showed a decrease in MMP-2 activity compared with the intact sedentary group (P<0.05). Our results suggest that the resistance training proposed in our work was efficient in reverting the deleterious effects of ovariectomy on bone tissue, and also produced modeling effects in intact rats. On the other hand, ovariectomy reduced the activity of MMP-2 and produced deleterious effects on bone tissue, mimicking menopause intrinsically.

Acute cardiorespiratory and metabolic responses during resistance exercise in the lactate threshold intensity.

The aims were both to determine lactate and ventilatory threshold during incremental resistance training and to analyze the acute cardiorespiratory and metabolic responses during constant-load resistance exercise at lactate threshold (LT) intensity. Ten healthy men performed 2 protocols on leg press machine. The incremental test was performed to determine the lactate and ventilatory thresholds through an algorithmic adjustment method. After 48 h, a constant-load exercise at LT intensity was executed. The intensity of LT and ventilatory threshold was 27.1±3.7 and 30.3±7.9% of 1RM, respectively (P=0.142). During the constant-load resistance exercise, no significant variation was observed between set 9 and set 15 for blood lactate concentration (3.3±0.9 and 4.1±1.4 mmol x L(-1), respectively. P=0.166) and BORG scale (11.5±2.9 and 13.0±3.5, respectively, P=0.783). No significant variation was observed between set 6 and set 15 for minute ventilation (19.4±4.9 and 22.4±5.5 L x min(-1), respectively, P=0.091) and between S3 and S15 for VO2 (0.77±0.18 and 0.83±0.16 L x min(-1), respectively, P=1.0). Constant-load resistance exercise at LT intensity corresponds to a steady state of ventilatory, cardio-metabolic parameters and ratings of perceived exertion.

Biomechanical responses of different rat tendons to nandrolone decanoate and load exercise.

Androgenic-anabolic steroids (AAS) have been associated with an increased incidence of tendon rupture. The aim of this study was to compare the biomechanical properties of the rat calcaneal tendon (CT), superficial flexor tendon (SFT), and deep flexor tendon (DFT), and to determine the effect of jump training in association with AAS. Animals were separated into four groups: sedentary, trained, AAS-treated sedentary rats (AAS), and AAS-treated and trained animals. Mechanical testing showed that the CT differed from the DFT and SFT, which showed similar mechanical properties. Jump caused the CT to exhibit an extended toe region, an increased resistance to tensional load, and a decreased elastic modulus, characteristics of an elastic tendon capable of storing energy. AAS caused the tendons to be less compliant, and the effects were reinforced by simultaneous training. The DFT was the most affected by training, AAS, and the interaction of both, likely because of its involvement in the toe-off step of jumping, which we suggest is related to the rapid transmission of force as opposed to energy storage. In conclusion, tendons are differently adapted to exercise, but responded equally to AAS, showing reduced flexibility, which is suggested to increase the risk of tendon rupture in AAS consumers.

Menopause: highlighting the effects of resistance training.

The increase in lifespan and in the proportion of elderly women has increased the focus on menopause induced physiological alterations. These modifications are associated with the elevated risk of several pathologies such as cardiovascular disease, diabetes, obesity, hypertension, dyslipidemia, non-alcoholic fat liver disease, among others. Because of estrogen levels decline, many tissue and organs (muscular, bone, adipose tissue and liver) are affected. Additionally, body composition suffers important modifications. In this sense, there is a growing body of concern in understanding the physiological mechanisms involved and establishing strategies to prevent and reverse the effects of menopause. The hormone reposition therapy, diet and physical exercise have been recommended. Among the diverse exercise modalities, resistance training is not commonly used as a therapeutic intervention in the treatment of menopause. Thus, the aim of this review was to analyze the physiological alterations on several organs and systems induced by menopause and ovariectomy (experimental model to reproduce menopause), as well as, to study the effects of resistance training in preventing and reverting these modifications. In conclusion, resistance training promotes beneficial effects on several organs and systems, mainly, on muscular, bone and adipose tissue, allowing for a better quality of life in this population.

MMP-2, jumping exercise and nandrolone in skeletal muscle.

Matrix metalloproteinases (MMPs) are crucial to the development and maintenance of healthy tissue. The aim of this study was to investigate MMP-2 activity in gastrocnemius, soleus, extensor digitorium longus (EDL) and tibialis anterior (TA) muscles after exercise associated with an anabolic androgenic steroid (AAS). Wistar rats were grouped into: sedentary (S); sedentary with AAS (AAS); trained without (T) and with (AAST) AAS. Exercised groups performed a 7-week water-jumping program. The exercise increased MMP-2 activity in gastrocnemius and soleus, but not in TA and EDL. The AAS treatment decreased MMP-2 activity of EDL, as compared to the S group, with no effect in gastrocnemius and soleus. The association of AAS and training restored the normal MMP activity of EDL. Training increases tissue turnover in primary motor muscles, which in turn respond differently to AAS treatment. This data may be useful for a better understanding of muscular physiology under AAS use.

Early remodeling of rat cardiac muscle induced by swimming training.

The aim of the present investigation was to study the effect of acute swimming training with an anaerobic component on matrix metallopeptidase (MMP) activity and myosin heavy chain gene expression in the rat myocardium. Animals (male Wistar rats, weighing approximately 180 g) were trained for 6 h/day in 3 sessions of 2 h each for 1 to 5 consecutive days (N = 5 rats per group). Rats swam in basins 47 cm in diameter and 60 cm deep filled with water at 33 to 35 degrees C. After the training period a significant increase (P < 0.05) was observed in the heart weight normalized to body weight by about 22 and 35% in the groups that trained for 96 and 120 h, respectively. Blood lactate levels were significantly increased (P < 0.05) in all groups after all training sessions, confirming an anaerobic component. However, lactate levels decreased (P < 0.05) with days of training, suggesting that the animals became adapted to this protocol. Myosin heavy chain-beta gene expression, analyzed by real time PCR and normalized with GAPDH gene expression, showed a significant two-fold increase (P < 0.01) after 5 days of training. Zymography analysis of myocardium extracts indicated a single approximately 60-kDa activity band that was significantly increased (P < 0.05) after 72, 96, and 120 h, indicating an increased expression of MMP-2 and suggesting precocious remodeling. Furthermore, the presence of MMP-2 was confirmed by Western blot analysis, but not the presence of MMP-1 and MMP-3. Taken together, our results indicate that in these training conditions, the rat heart undergoes early biochemical and functional changes required for the adaptation to the new physiological condition by tissue remodeling.

Early remodeling of rat cardiac muscle induced by swimming training

The aim of the present investigation was to study the effect of acute swimming training with an anaerobic component on matrix metallopeptidase (MMP) activity and myosin heavy chain gene expression in the rat myocardium. Animals (male Wistar rats, weighing approximately 180 g) were trained for 6 h/day in 3 sessions of 2 h each for 1 to 5 consecutive days (N = 5 rats per group). Rats swam in basins 47 cm in diameter and 60 cm deep filled with water at 33 to 35°C. After the training period a significant increase (P < 0.05) was observed in the heart weight normalized to body weight by about 22 and 35 percent in the groups that trained for 96 and 120 h, respectively. Blood lactate levels were significantly increased (P < 0.05) in all groups after all training sessions, confirming an anaerobic component. However, lactate levels decreased (P < 0.05) with days of training, suggesting that the animals became adapted to this protocol. Myosin heavy chain-ß gene expression, analyzed by real time PCR and normalized with GAPDH gene expression, showed a significant two-fold increase (P < 0.01) after 5 days of training. Zymography analysis of myocardium extracts indicated a single ~60-kDa activity band that was significantly increased (P < 0.05) after 72, 96, and 120 h, indicating an increased expression of MMP-2 and suggesting precocious remodeling. Furthermore, the presence of MMP-2 was confirmed by Western blot analysis, but not the presence of MMP-1 and MMP-3. Taken together, our results indicate that in these training conditions, the rat heart undergoes early biochemical and functional changes required for the adaptation to the new physiological condition by tissue remodeling.

Adaptação enzimática da LDH em ratos submetidos a treinamento aeróbio em esteira e laser de baixa intensidade / Adaptation of LDH enzyme in rats undergoing aerobic treadmill training and low intensity laser therapy

OBJETIVO: Verificar a atividade e padrão eletroforético da LDH em resposta ao exercício em esteira em ratos submetidos à fotoestimulação por laser de baixa intensidade (780 etam). MÉTODO: Foram utilizados nesse estudo 54 ratos machos jovens (30dias), Winstar, com peso inicial médio de 112 ± 4,7g, os quais foram divididos em quatro grupos: dois permaneceram em repouso, GRC (grupo repouso controle, n= 9) e GRL (grupo repouso laser, n= 10), sendo o segundo irradiado por laser, e outros dois foram submetidos ao treinamento aeróbio e testes de esforço crescente em esteira (em degraus descontínuos) visando à determinação do limiar de anaerobiose (LA) durante 5 semanas, GEC (grupo exercício controle, n= 16) e GEL (grupo exercício laser, n= 19), sendo o último também irradiado por laser. O laser foi aplicado no quadríceps, glúteo máximo, sóleo e tibial anterior (TA), bilateralmente, imediatamente após cada sessão de treinamento, usando: 3,8J/cm², 15mW, 10s, modo contínuo, durante 5 semanas. Amostras de sóleo, TA e coração foram removidas 48 horas após a última sessão de exercício para análise eletroforética e espectrofotométrica. A estatística foi realizada através do teste ANOVA e post-hoc de TUKEY. O nível de significância foi considerado (p< 0,05). RESULTADOS: Foram observadas reduções na atividade da LDH causadas pelo laser (de 19 por cento a 30 por cento), exercício (de 41 por cento a 66 por cento) e as ações combinadas (de 47 por cento a 66 por cento) (p< 0,01). A eletroforese mostrou uma predominância da subunidade B para o sóleo e coração, e uma predominância da subunidade A no TA. CONCLUSÕES: Estes dados sugerem uma melhor resposta adaptativa dos animais ao treinamento aeróbio associado à terapia laser, no que se refere à otimização da via oxidativa.

Limiar de anaerobiose em ratos submetidos a treinamento fisico em esteira e laser de baixa intensidade / Anaerobic threshold in rats subjected to aerobic treadmill training program and low-intensity laser

O proposito deste estudo foi verificar o limiar de anaerobiose em resposta ao exercicio em estera em ratos submetidos a fotoestimulacao por laser de baixa intensidade (780nm). Metodo: foram utilizados neste estudo 40 ratos machos jovens (30dias), wistar com peso inicial medio de 111+-10g, os quais foram divididos em dois grupos: 1-grupo exercicio controle (GEC) e 2-grupo exercicio laser (GEL), ambos submetidos a um treinamento aerobio em esteira e a testes de esforco crescente (em degraus descontinuos) visando a determinacao do limiar de anaerobiose. O laser foi aplicado nos principais musculos da marcha, imediatamente apos cada sessao de treinamento. Para a dosagem do lactato utilizou-se um lactimetro. A estatistica foi realizada por meio dos testes ANOVA e post-hoc de TUKEY. O nivel de significancia foi considerado (p<-0,05). resultados: apos o periodo de treinamento os dois grupos exibiram aumento na velocidade maxima da corrida e o limiar de anaerobiose se mostrou deslocado para um nivel de maior esforco (p<0,01). As medidas de lactacidemia mostraram ligeira reducao durante a obtencao do limiar de anaerobiose, sobretudo no GEC. Entretanto, nao houve diferenca estatisticamente significativa entre os grupos para as variaveis analisadas, apesar de o GEL ter mostrado comportamento diferenciado no decorrer das semanas, no que se refere ao padrao da curva de esforco. Conclusoes: esses dados sugerem que alteracoes na lactacidemia, em ratos treinados, permitem a determinacao do limiar de anaerobiose e que o treinamento aerobico possibilitou adaptacoes fisiologicas no sentido de aumento na capacidade oxidativa dos animais

Remodelamento muscular induzido por treinamento: expressao de miosina em musculo esqueletico de rato: uma anlise qualitativa / Effects of training in muscular remodeling: myosin expression in rat skeletal muscle - a qualitative analysis

O musculo possui uma habiliade inerente de adpatacao diante de variadas condicoes, como tipo de inervacao, atuacao de hormonios, atividade contratil (treinamento), condicao de alongamento, o proprio crescimento pos-natal, entre outros. Ha grande correlacao entre a isoforma de cadeia pesada de miosina (CPM) expressa e a funcao muscular. O presente estudo teve por objetivo estudar o remodelamento muscular por meioda analise da expressao das diferentes isoformas de CPM de musculo esqueletico em ratos submetidos a treinamento fisico. A metodologia utilizada consistiu em treinamento de ratos albinos (n=10), machos, em protocolo de natacao, em um periodo de 6 horas/dia, em 3 sessoes de 2 horas, com intervalos de 30 minutos entre cadasessao, totalizando 5 dias de treinamento. Ao termino do treinamento, os animais foram sacrificados para extracao do musculo soleo. Foi feita extracao de RNA total e posterior reacao de RT-PCR utilizando oligonucleotideos iniciadores especificos para as diferentes isoformas de CPM. Tambem foi realizada, a partir de extratos proteicos do musculo retirado, a separacao eletroforetica das isiformas de CPM, utilizando SDS-PAGE com gradiente de (7 - 10 por cento). Os resultados obtidos com a tecnica de RT-PCR demonstrarm expressao de todas as isoformas de CPM, tanto em ratos sedentarios como nos treinados. Apesar de a analise nao ter sido feita de forma quantitativa, parece haver tendencia de aumento especialmente das isiformas IIa e IIx com a evolucao do treinamento. A separacao eletroforetica das isoformas mostrou que nao houve alteracao na expressao das isoformas de CPM (I, IIa, IIb e IIx) com o treinamento

Inhibition of renal electrolyte excretion by gabaergic pathways of the lateral hypothalamic area

Injection of gamma butyric acid (GABA) into the lateral hypothalamic area of unrestrained conscious rats caused a decrease in renal electrolyte excretion with an increase in urinary flow. When picrotoxin, a specific inhibito of gabaergic pathways, was administered, a significant increase in renal water and electrolyte excretion occured. The effect of simultaneous injection of pidrotoxin and GABA into the same site indicate that picrotoxin was less potent in reversing tyhe effect induceb by GABA than GABA was in reversing the effect of picrotoxin. We conclude that GABA acts directly on the neuronal mechanisms involved in the control of water and elecltrolyte excretion, perhaps by exerting a tonic inhibitory action on renal electrolyte excretion

Participation of opiate pathways in the lateral hypothalamic area in the control of renal electrolyte and water excretion

Injection of Met-enkephalin (0.05, 0.25 and 0.50 µg in 1 µl) solutions into the lateral hypothalamic area (LHA), of unrestrained and unanesthetized rats caused a significant decrease of sodium (0.30 ñ 0.13 to 0.07 ñ 0.01, P < 0.05) and potassium (0.61 ñ 0.17 to 0.21 ñ 0.04, P < 0.05) excretion. When the blocking agent nalaxone (0.20 µg in 1 µl) was injected alone, a signifricant increase of sodium (0.34 ñ 0.04 to 0.96 ñ 0.28, P < 0.05) and potassium (0.76 ñ 0.13 to 1.72 ñ 0.30, P < 0.05) excretion was observed. However, a dose-response relationship was not observed. However, when in another experiment naloxone was injected before Met-enkepalin into the same area, reversal of the effect of naloxone occured, with decreased sodium and potassium excretion. We conclude that the enkephalinergic pathway of the LHA when stimulated with Met-enkephalin plays an inhibitory role in the contorl of sodium and potassium excretion

Characteristics of toad bladder urinary acidification

The urinary acidification system present in the bladder of the toad Bufo marinus ictericus was investigated by means of an improved technique of mounting the membrane that minimizes the edge damage when the bladder is placed as a sheet between lucite half chambers. In ouabain-treated bladders in the absence of exogenous CO2, acification rates were similar to those observed for turtle bladder. The presence of 1%CO2 at the serosal gas phase increased proton secretion (JH). Stimulation of JH was also observed when the cell pH was decreased by back diffusion of salicylic acid added to the mucosal(M) compartment. The estimate of the passive proton permeability of this epithelium as a whole yielded values around 1 x 10**-4cm/s. The maximum pH gradient that could be established across the membrane in the short circuit condition (about 3 pH units) was taken as the apparent proton-motive force (PMF') of the system and these values were similar to those observed in the turtle bladder. Luminal membrane depolarization caused by substitution of NaCl by KCl in Ringer solution led to an increase in JH at MpH = 7.3 without altering the PMF', which suggests that the electrical potential difference across the luminal membrane in ouabain-treated bladders is negligible when M pH is sufficiently acid to abolish H+ secretion