ABSTRACT
BACKGROUND:: Baroreceptors act as regulators of blood pressure (BP); however, its sensitivity is impaired in hypertensive patients. Among the recommendations for BP reduction, exercise training has become an important adjuvant therapy in this population. However, there are many doubts about the effects of resistance exercise training in this population. OBJECTIVE:: To evaluate the effect of resistance exercise training on BP and baroreceptor sensitivity in spontaneously hypertensive rats (SHR). METHOD:: Rats SHR (n = 16) and Wistar (n = 16) at 8 weeks of age, at the beginning of the experiment, were randomly divided into 4 groups: sedentary control (CS, n = 8); trained control (CT, n = 8); sedentary SHR (HS, n = 8) and trained SHR (HT, n = 8). Resistance exercise training was performed in a stairmaster-type equipment (1.1 × 0.18 m, 2 cm between the steps, 80° incline) with weights attached to their tails, (5 days/week, 8 weeks). Baroreceptor reflex control of heart rate (HR) was tested by loading/unloading of baroreceptors with phenylephrine and sodium nitroprusside. RESULTS:: Resistance exercise training increased the soleus muscle mass in SHR when compared to HS (HS 0.027 ± 0.002 g/mm and HT 0.056 ± 0.003 g/mm). Resistance exercise training did not alter BP. On the other hand, in relation to baroreflex sensitivity, bradycardic response was improved in the TH group when compared to HS (HS -1.3 ± 0.1 bpm/mmHg and HT -2.6 ± 0.2 bpm/mmHg) although tachycardia response was not altered by resistance exercise (CS -3.3 ± 0.2 bpm/mmHg, CT -3.3 ± 0.1 bpm/mmHg, HS -1.47 ± 0.06 bpm/mmHg and HT -1.6 ± 0.1 bpm/mmHg). CONCLUSION:: Resistance exercise training was able to promote improvements on baroreflex sensitivity of SHR rats, through the improvement of bradycardic response, despite not having reduced BP. FUNDAMENTO:: Os barorreceptores atuam como reguladores da pressão arterial (PA); no entanto, sua sensibilidade encontra-se prejudicada em pacientes hipertensos. Dentre as recomendações para a redução da PA, o treinamento físico tem se tornado um importante adjunto na terapia dessa população. Porém, ainda há diversos questionamentos sobre os efeitos de treinamento físico resistido nessa população. OBJETIVO:: Avaliar o efeito do treinamento físico resistido na PA e na sensibilidade de barorreceptores em ratos espontaneamente hipertensos (SHR). MÉTODO:: Ratos SHR (n = 16) e Wistar (n = 16) com 08 semanas de idade foram aleatoriamente divididos em 4 grupos: controle sedentário (CS, n = 8); controle treinado (CT, n = 8); SHR sedentário (HS, n = 8) e SHR treinado (HT, n = 8). O treinamento físico foi realizado em aparato com degraus (1,1 × 0,18 m, 2 cm entre os degraus, 80° inclinação) com peso fixado na cauda, (5 vezes por semana durante 8 semanas). O controle barorreflexo da frequência cardíaca (FC) foi testado com estímulos de fenilefrina e nitroprussiato de sódio. RESULTADOS:: O treinamento resistido foi capaz de aumentar a massa muscular do sóleo em ratos SHR (HS 0,027 ± 0,002 g/mm e HT 0,056 ± 0,003 g/mm). Não houve alteração da PA com o treinamento. Por outro lado, houve melhora na resposta bradicárdica da sensibilidade barorreflexa no grupo HT (HS -1,3 ± 0,1 bpm/mmHg e HT -2,6 ± 0,2 bpm/mmHg), no entanto, a resposta taquicárdica não foi alterada pelo exercício resistido (CS -3,3 ± 0,2 bpm/mmHg, CT -3,3 ± 0,1 bpm/mmHg, HS -1,47 ± 0,06 e HT -1,6 ± 0,1). CONCLUSÃO:: O exercício físico resistido foi capaz de otimizar a sensibilidade barorreflexa dos ratos SHR por meio da melhora à resposta bradicárdica, apesar de não alterar a PA.
Subject(s)
Baroreflex/physiology , Hypertension/rehabilitation , Physical Conditioning, Animal/physiology , Resistance Training , Animals , Hypertension/physiopathology , Male , Rats , Rats, Inbred SHR , Rats, WistarABSTRACT
Abstract Background: Baroreceptors act as regulators of blood pressure (BP); however, its sensitivity is impaired in hypertensive patients. Among the recommendations for BP reduction, exercise training has become an important adjuvant therapy in this population. However, there are many doubts about the effects of resistance exercise training in this population. Objective: To evaluate the effect of resistance exercise training on BP and baroreceptor sensitivity in spontaneously hypertensive rats (SHR). Method: Rats SHR (n = 16) and Wistar (n = 16) at 8 weeks of age, at the beginning of the experiment, were randomly divided into 4 groups: sedentary control (CS, n = 8); trained control (CT, n = 8); sedentary SHR (HS, n = 8) and trained SHR (HT, n = 8). Resistance exercise training was performed in a stairmaster-type equipment (1.1 × 0.18 m, 2 cm between the steps, 80° incline) with weights attached to their tails, (5 days/week, 8 weeks). Baroreceptor reflex control of heart rate (HR) was tested by loading/unloading of baroreceptors with phenylephrine and sodium nitroprusside. Results: Resistance exercise training increased the soleus muscle mass in SHR when compared to HS (HS 0.027 ± 0.002 g/mm and HT 0.056 ± 0.003 g/mm). Resistance exercise training did not alter BP. On the other hand, in relation to baroreflex sensitivity, bradycardic response was improved in the TH group when compared to HS (HS -1.3 ± 0.1 bpm/mmHg and HT -2.6 ± 0.2 bpm/mmHg) although tachycardia response was not altered by resistance exercise (CS -3.3 ± 0.2 bpm/mmHg, CT -3.3 ± 0.1 bpm/mmHg, HS -1.47 ± 0.06 bpm/mmHg and HT -1.6 ± 0.1 bpm/mmHg). Conclusion: Resistance exercise training was able to promote improvements on baroreflex sensitivity of SHR rats, through the improvement of bradycardic response, despite not having reduced BP.
Resumo Fundamento: Os barorreceptores atuam como reguladores da pressão arterial (PA); no entanto, sua sensibilidade encontra-se prejudicada em pacientes hipertensos. Dentre as recomendações para a redução da PA, o treinamento físico tem se tornado um importante adjunto na terapia dessa população. Porém, ainda há diversos questionamentos sobre os efeitos de treinamento físico resistido nessa população. Objetivo: Avaliar o efeito do treinamento físico resistido na PA e na sensibilidade de barorreceptores em ratos espontaneamente hipertensos (SHR). Método: Ratos SHR (n = 16) e Wistar (n = 16) com 08 semanas de idade foram aleatoriamente divididos em 4 grupos: controle sedentário (CS, n = 8); controle treinado (CT, n = 8); SHR sedentário (HS, n = 8) e SHR treinado (HT, n = 8). O treinamento físico foi realizado em aparato com degraus (1,1 × 0,18 m, 2 cm entre os degraus, 80° inclinação) com peso fixado na cauda, (5 vezes por semana durante 8 semanas). O controle barorreflexo da frequência cardíaca (FC) foi testado com estímulos de fenilefrina e nitroprussiato de sódio. Resultados: O treinamento resistido foi capaz de aumentar a massa muscular do sóleo em ratos SHR (HS 0,027 ± 0,002 g/mm e HT 0,056 ± 0,003 g/mm). Não houve alteração da PA com o treinamento. Por outro lado, houve melhora na resposta bradicárdica da sensibilidade barorreflexa no grupo HT (HS -1,3 ± 0,1 bpm/mmHg e HT -2,6 ± 0,2 bpm/mmHg), no entanto, a resposta taquicárdica não foi alterada pelo exercício resistido (CS -3,3 ± 0,2 bpm/mmHg, CT -3,3 ± 0,1 bpm/mmHg, HS -1,47 ± 0,06 e HT -1,6 ± 0,1). Conclusão: O exercício físico resistido foi capaz de otimizar a sensibilidade barorreflexa dos ratos SHR por meio da melhora à resposta bradicárdica, apesar de não alterar a PA.
Subject(s)
Animals , Male , Rats , Physical Conditioning, Animal/physiology , Baroreflex/physiology , Resistance Training , Hypertension/rehabilitation , Rats, Inbred SHR , Rats, Wistar , Hypertension/physiopathologyABSTRACT
The Diabetes Mellitus (DM) is a chronic disease associated with loss of brain regions such as the cerebellum, increasing the risk of developing neurodegenerative diseases such as Parkinson's disease (PD). In the brain of diabetic and PD organisms the insulin/IGF-1 signaling is altered. Exercise training is an effective intervention for the prevention of neurodegerative diseases since it release neurotrophic factors and regulating insulin/IGF-1 signaling in the brain. This study aimed to evaluate the proteins involved in the insulin/IGF-1 pathway in the cerebellum of diabetic rats subjected to exercise training protocol. Wistar rats were distributed in four groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD) and trained diabetic (TD). Diabetes was induced by Alloxan (ALX) (32mg/kgb.w.). The training program consisted in swimming 5days/week, 1h/day, during 6 weeks, supporting an overload corresponding to 90% of the anaerobic threshold. At the end, cerebellum was extracted to determinate the protein expression of GSK-3ß, IRß and IGF-1R and the phosphorylation of ß-amyloid, Tau, ERK1+ERK2 by Western Blot analysis. All dependent variables were analyzed by one-way analysis of variance with significance level of 5%. Diabetes causes hyperglycemia in both diabetic groups; however, in TD, there was a reduction in hyperglycemia compared to SD. Diabetes increased Tau and ß-amyloid phosphorylation in both SD and TD groups. Furthermore, aerobic exercise increased ERK1+ERK2 expression in TC. The data showed that in cerebellum of diabetic rats induced by alloxan there are some proteins expression like Parkinson cerebellum increased, and the exercise training was not able to modulate the expression of these proteins.
