Gustavo Gomes de Araujo

Exercise training in the aerobic/anaerobic metabolic transition prevents glucose intolerance in alloxan-treated rats

BackgroundNinety percent of cases of diabetes are of the slowly evolving non-insulin-dependent type, or Type 2 diabetes. Lack of exercise is regarded as one of the main causes of this disorder. In this study we analyzed the effects of physical exercise on glucose homeostasis in adult rats with type 2 diabetes induced by a neonatal injection of alloxan.MethodsFemale Wistar rats aged 6 days were injected with either 250 mg/kg of body weight of alloxan or citrate buffer 0.01 M (controls). After weaning, half of the animals in each group were subjected to physical training adjusted to meet the aerobic-anaerobic metabolic transition by swimming 1 h/day for 5 days a week with weight overloads. The necessary overload used was set and periodically readjusted for each rat through effort tests based on the maximal lactate steady state procedure. When aged 28, 60, 90, and 120 days, the rats underwent glucose tolerance tests (GTT) and their peripheral insulin sensitivity was evaluated using the HOMA index.ResultsThe area under the serum glucose curve obtained through GTT was always higher in alloxan-treated animals than in controls. A decrease in this area was observed in trained alloxan-treated rats at 90 and 120 days old compared with non-trained animals. At 90 days old the trained controls showed lower HOMA indices than the non-trained controls.ConclusionNeonatal administration of alloxan induced a persistent glucose intolerance in all injected rats, which was successfully counteracted by physical training in the aerobic/anaerobic metabolic transition.

Metabolic responses to acute physical exercise in young rats recovered from fetal protein malnutrition with a fructose-rich diet

BackgroundMalnutrition in utero can program the fetal tissues, making them more vulnerable to metabolic disturbances. Also there is association between excessive consumption of fructose and the development of metabolic syndrome. However, there is little information regarding the acute effect of physical exercise on subjects recovered from malnutrition and/or fed with a fructose-rich diet. The objective of this study was to evaluate the metabolic aspects and the response to acute physical exercise in rats recovered from fetal protein malnutrition with a fructose-rich diet.MethodsPregnant Wistar rats were fed with a balanced (B) diet or a low-protein (L) diet. After birth and until 60 days of age, the offspring were distributed into four groups according to the diet received: B: B diet during the whole experiment; balanced/fructose (BF): B diet until birth and fructose-rich (F) diet afterwards; low protein/balanced (LB): L diet until birth and B diet afterwards; low protein/fructose (LF): L diet until birth and F diet afterwards.ResultsThe excess fructose intake reduced the body weight gain, especially in the BF group. Furthermore, the serum total cholesterol and the LDL cholesterol were elevated in this group. In the LF group, the serum total cholesterol and the muscle glycogen increased. Acute physical exercise increased the serum concentrations of glucose, triglycerides, HDL cholesterol and liver lipids and reduced the concentrations of muscle glycogen in all groups.ConclusionAn excess fructose intake induced some signs of metabolic syndrome. However, protein malnutrition appeared to protect against the short term effects of fructose. In other hand, most responses to acute physical exercise were not influenced by early malnutrition and/or by the fructose overload.

Padronização de um protocolo experimental de treinamento periodizado em natação utilizando ratos Wistar

Verificar os efeitos de 12 semanas de treinamento periodizado de natacao em ratos sobre os valores de glicogenio muscular (GM) e hepatico (GH), capacidade aerobia (LAn) e anaerobia (Tlim) e creatina quinase (CK). Foram utilizados 70 ratos da linhagem Wistar com 60 dias, adaptados individualmente ao meio liquido por duas semanas. Os animais foram divididos em grupos: controle (GC, n = 40) e periodizado (GP, n = 30); a intensidade do treinamento foi equivalente ao peso corporal do animal (% do PC). O treinamento (T) para o GP foi dividido em periodos preparatorio basico (PPB, seis semanas), especifico (PPE, 4,5 semanas) e polimento (PP, 1,5 semana), tendo como estimulos intensidades leve (4% do PC), moderada (5% do PC), pesada (6% do PC) e intensa (13% do PC). Vinte e quatro horas apos a adaptacao, 10 ratos do GC foram sacrificados e avaliados pelo teste de lactato minimo para mensuracao dos valores de linha de base de GM, GH, CK, LAn e Tlim. Os dez animais restantes do GC e GP foram sacrificados ao final de cada periodo de T. O treinamento periodizado aumentou a concentracao de glicogenio muscular ao final do periodo de polimento. O glicogenio hepatico nao se alterou no GC, porem no GP houve reducao significativa no inicio do periodo especifico com elevacao no periodo de polimento. A concentracao de CK nao se modificou ao final dos PPB, PPE e PP. O LAn reduziu ao longo do periodo experimental no GC, mas ao final do PP para o GP, o LAn atingiu os mesmos valores do inicio do treinamento. O Tlim aumentou no PP. Desse modo, pode-se concluir que o treinamento periodizado provocou supercompensacao energetica ao final da periodizacao. A capacidade anaerobia aumentou no PP bem como o LAn, que obteve maiores valores em relacao ao GC nesse periodo.

Máxima fase estável de lactato em ratos obesos de ambos os gêneros

The purpose of this study was to identify the exercise intensity equivalent to the aerobic/anaerobic metabolic transition in obese rats of both genders using the maximal lactate steady state (MLSS) protocol. Four groups of rats were tested on MLSS protocol (swimming exercise): male control n=10, female control n=10, male obese n=10 and female obese n=10, after suitable adaptation to exercise in liquid medium and obesity induction by monossodic glutamate (MSG) administration. The obese groups had significant increase in subcutaneous adipose tissue as well as mesenteric and retroperitoneal fat depots comparing to the control groups. The Lee index was higher in the obese animals in comparison to their respective controls. It was possible to identify the MLSS at 6.0% of body weight for both obese groups. Concerning the female control group, the MLSS was determined at the intensity of 5.0% of body weight, whereas for the male control at 4.5% of body weight. It was concluded that obesity induced by MSG interferes in lactate kinetics during exercise and alters the effort intensity corresponding to the metabolic transition in both genders.

Maximal lactate steady state for aerobic evaluation of swimming mice.

The maximal lactate steady state (MLSS) has been considered the gold standard method to determine aerobic/anaerobic metabolism transition during continuous exercise executed by human beings and rats. Therefore, the aim of the present study was to determine MLSS for aerobic evaluation in swimming mice. Twenty-five adult male mice (90-day-old animals) were adapted to the deep aquatic environment at the temperature of 31xa0±xa01°C. The mice were submitted to five continuous exercise loads of 3, 4, 5, 6 and 7% of the body weight (bw) tied to the back, executed with 25-min duration and 48-h intervals between them. Blood samples were collected from the tail during swimming exercise (rest, 5, 10, 15, 20 and 25xa0min) for blood lactate concentration (LAC) determinations. The individual MLSS was considered as the highest intensity in which the increase on the LAC was equal to or below 1xa0mmolxa0l −xa01 from the 10th to the 25th minute of exercise. The results showed that 36% of the swimming mice presented MLSS at 4% bw, 20% at 3% bw and 6% bw, 16% at 5% bw and 8% at 7% bw. The LAC at the MLSS was 5.78xa0±xa00.29xa0mmolxa0l −xa01 (4.40–6.67xa0mmolxa0l −xa01 ). These results indicate that the MLSS of mice swimming with additional weight for the final 15 of 25xa0min of exercise could be determined.

Muscle protein metabolism in neonatal alloxan-administered rats: effects of continuous and intermittent swimming training

BackgroundThis study aimed to examine the effects of intermittent and continuous swimming training on muscle protein metabolism in neonatal alloxan-administered rats.MethodsWistar rats were used and divided into six groups: sedentary alloxan (SA), sedentary control (SC), continuous trained alloxan (CA), intermittent trained alloxan (IA), continuous trained control (CC) and intermittent trained control (IC). Alloxan (250 mg/kg body weight) was injected into newborn rats at 6 days of age. The continuous training protocol consisted of 12 weeks of swimming training in individual cylinder tanks while supporting a load that was 5% of body weight; uninterrupted swimming for 1 h/day, five days a week. The intermittent training protocol consisted of 12 weeks of swimming training in individual cylinder tanks while supporting a load that was 15% of body weight; 30 s of activity interrupted by 30 s of rest for a total of 20 min/day, five days a week.ResultsAt 28 days, the alloxan animals displayed higher glycemia after glucose overload than the control animals. No differences in insulinemia among the groups were detected. At 120 days, no differences in serum albumin and total protein among the groups were observed. Compared to the other groups, DNA concentrations were higher in the alloxan animals that were subjected to continuous training, whereas the DNA/protein ratio was higher in the alloxan animals that were subjected to intermittent training.ConclusionIt was concluded that continuous and intermittent training sessions were effective in altering muscle growth by hyperplasia and hypertrophy, respectively, in alloxan-administered animals.

Respostas fisiológicas ao exercício agudo em ratos obesos tratados com metformina

The purpose of the present study was to investigate the physiological responses to intense exercise in obese Wistar rats treated with metformin. To induce obesity, all animals were infused with monosodic glutamate (4 mg/g of body weight) via subcutaneous injection. The rats were divided in 4 groups according to the received treatment: obese control (OC); obese metformin ( OM); obese control exercise (OCE) and obese metformin exercise (OME). Before and after one session of intense exercise the following parameters were measured: serum glucose (mg/dl), triglycerides (g/100g), total cholesterol (mg/dl) and haematocrit (%). The values of serum glucose and total cholesterol were significantly reduced in control exercise group (OCE - 68.4 ± 14.7 and 70.8 ±18.3) compared to obese control sedentary group (OC - 83.6 ± 12.8 and 91.3 ± 9.6). The isolate metformin infusion decreased the glucose concentration from 83.6 ± 12.8 (OC) to 70.8 ± 5.9 (OM). On the other hand, metformin associated with exercise increased the availability of free triglycerides after exercise (OM - 166.6 ± 11.3, OME - 184.0 ± 4.3). In conclusion, the present intervention program (intense physical exercise) showed to be efficient on glicemic homeostasis, as well as on lipids circulatory levels in obese rats treated with metformin.