Beta-hydroxy-beta-methylbutyrate associated with low-intensity exercise training improves skeletal muscle regeneration through the IGF-Akt pathway

The effect of beta-hydroxy-beta-methylbutyrate (HMB) supplementation associated with exercise training at different intensities and frequencies on skeletal muscle regeneration of muscle-injured rats was investigated. Male Wistar rats were divided into sedentary and trained groups. The sedentary groups were subdivided into non-injured (SED-Ct), non-injured supplemented with HMB (SED-Ct-HMB), injured (SED), and injured with HMB (SED-HMB), and the trained groups were injured, supplemented with HMB, and then divided into training three times a week without load (HT3) or with load (HT3L) and training five times a week without load (HT5) and with load (HT5L). The rats received a daily dose of HMB associated with 60 min of swimming with or without 5% body mass load for 14 days. On the 15th day, cryoinjury was performed in the right tibialis anterior muscle (TA), and 48 h later, supplementation and training continued for 15 days. After the last session, the TA was dissected and a cross-sectional area (CSA) of muscle fibers was used to determine the percentage of CSA fibers and connective tissue (%CT), as well as the total and phosphorylated protein contents. SED-HMB showed increased CSA and decreased %CT and TGF-β when compared to SED. HT3 showed increased CSA and reduced %CT accompanied by increased IGF-1/Akt, myogenin, and MuRF1, and decreased TGF-β. The CSA of HT5L also increased, but at the cost of a higher %CT compared to the other groups. Our results demonstrated that HMB associated with training without load and with lower frequency per week may be a valuable strategy for skeletal muscle regeneration.

Changes in types of muscle fibers induced by transcutaneous electrical stimulation of the diaphragm of rats

The objective of the present study was to assess the effect of transcutaneous electrical diaphragmatic stimulation (TEDS) on different types of diaphragm muscle fibers. Male Wistar rats (8-12 weeks old) were divided into 2 experimental groups (N = 8 in each group): 1) control, 2) animals submitted to TEDS [frequency = 50 Hz; T ON/T OFF (contraction/relaxation time) = 2/2 s; pulse duration = 0.4 ms, intensity = 5 mA with a 1 mA increase every 3 min for 20 min] for 7 days. After completing this treatment period, the I, IIA, IIB, and IID diaphragm muscle fibers were identified using the mATPase technique. Statistical analysis consisted of the normality, homoscedasticity and t-tests (P < 0.05). There was a 19.6 percent (P < 0.05) reduction in the number of type I fibers and a 49.7 percent increase (P < 0.05) in type IID fibers in the TEDS group compared with the control group. An important result of the present study was that electrical stimulation with surface electrodes was efficient in altering the distribution of fibers in diaphragm muscle. This therapeutic resource could be used in the treatment of respiratory muscle alterations.

Análise quali-quantitativa da influência das atividades físico-desportivas na saúde de crianças e jovens pertencentes a um programa de educação pelo esporte na Cidade do Natal - Brasil / Quali-quantitative analysis of influence of sports activities in the health of children and young people in a Program of Sports Education in Natal-Brasil

PURPOSE: Verify in a specific social totality of lower socioeconomical level, what would be the main interest for parents to place their children in an Educational Program Through Sport. To evaluate and classify children and young people as to physical aptitude related to health through scientifically validated indicators and to relate them to socioeconomical condition. To verify compatibility between qualitative and quantitative researches. METHODS: The sample of the qualitative study is composed of 22 subjects, characterizing itself as a non probabilistic sample of the causal type. Semi structured interview techniques in an individual situation and free evocation of words were used, based on the presuppositions of the Theory of Social Representations. A mixed sample, of the quantitative study, is composed of 67 children, where the possibility of relationship of the family income variable was confirmed with the variables: Body Composition and Flexibility, that compose the physical aptitude indicator related to health and the social representation of the parents. RESULTS: The qualitative results refer to biological aspects of health that constitute the central nucleus of the social representation of sport. In the quantitative aspect, it is verified that there was no correlation statistically, significant between the indexes of physical aptitude and the family income. CONCLUSION: The reason attributed to the physical-sport activities by the parents or relatives of the children, is based on the benefits to biological health and is shown by the children's good performance in the applied aptitude tests. There is not significant correlation between the index of physical aptitude applied to health, which reinforces the possibility of the parents social representation and the children's behavior.

Partial recovery of erythrocyte glycogen in diabetic rats treated with phenobarbital

Erythorocytes may play a role in glucose homeostasis during the postprandial period. Erythrocytes from diabetic patients are defective in glucose transport and metabolism, functions that may affect glycogen storage. Phenobarbital, a hepatic enzyme inducer, has been used in the treatment of patients with non-insulin-dependent diabetes mellitus (NIDDM), increasing the insulin-mediated glucose disposal. We studied the effects of phenobarbital treatment in vivo on glycemia and erythrocyte glycogen content in control and alloxan-diabetic rats during the postprandial period. In control rats (blood glucose, 73 to 111 mg/dl in femoral and suprahepatic veins) the erythrocyte glycogens content was 45.4 + 1.1 and 39.1 + 0.8 mug/g Hb (mean + SEM, N = 4-6) in the femoral artery and vein, respectively, and 37.9 +1.1 in the portal vein and 47.5 + 0.9 in the suprahepatic vein. Diabetic rats (blood glucose 300-350 mg/dl) presented low (p<0.05) erythrocyte glycogen content, i.e., 9.6 + 0.1 and 7.1 + 0.7 mug/g Hb in the femoral artery and vein, respectively, and 10.0 + 0.7 and 10.7 + 0.5 in the portal and suprahepatic veins, respectively. After 10 days of tratment, phenobarbital (0.5 mg/ml in the drinking water) did not change blood glucose or erythrocyte glycogen content in control rats. In diabetic rats, however, it lowered (P<0.05) blood glucose in the femoral artery (from 305 + 18 to 204 + 45 mg/dl) and femoral vein (from 300 + 11 to 174 + 48 mg/dl) and suprahepatic vein (from 350 + 10 to 174 + 42 mg/dl), but the reduction was not sufficient for complete recovery. Phenobarbital also stimulated the glycogens synthesis, leading to a partial recovery of glycogen stores in erythrocytes. In treated rats, erythrocyte glycogen content increased to 20.7 + 3.8 mug/g Hb in the femoral artery and 30.9 + 0.9 mug/g Hb in the suprahepatic veins (p<0.05). These data indicate that phenobarbital activated some of the insulin-stimulated glucose matabolism steps which were depressed in diabetic srythrocytes, supporting the view that erythrocytes participate in glucose homeostasis.