The present study investigated the role of swimming training on cerebral metabolism and hippocampus concentrations of insulin and IGF-1 in diabetic rats. Wistar rats were divided in sedentary control (SC), trained control (TC), sedentary diabetic (SD), and trained diabetic (TD). Diabetes was induced by Alloxan (35 mg kg(-1) b.w.). Training program consisted in swimming 5 days/week, 1 h/day, 8 weeks, supporting a load corresponding to 90% of maximal lactate steady state (MLSS). For MLSS determination, rats were submitted to three sessions of 25-min supporting loads of 4, 5, or 6% of body wt, with intervals of 1 week. Blood samples were collected every 5 min for lactate determination. An acute exercise test (25 min to 90% of MLSS) was done in 7th week to confirm the efficacy of training. All dependent variables were analyzed by one-way analysis of variance (ANOVA) and a significance level of P < 0.05 was used for all comparisons. The Bonferroni test was used for post hoc comparisons. At the end of the training period, rats were sacrificed and sample blood was collected for determinations of serum glucose, insulin, GH, and IGF-1. Samples of gastrocnemius muscle and liver were removed to evaluate glycogen content. Hippocampus was extracted to determinate glycogen, insulin, and IGF-1 contents. Diabetes decreased serum GH, IGF-1, and liver glycogen stores in SD. Diabetes also increased hippocampus glycogen and reduced hippocampus IGF-1 content. Physical training recovered liver and hippocampus glycogen stores and promoted increases in serum IGF-1 in TD group. Physical training restored hippocampus IGF-1 content in diabetic group. It was concluded that in diabetic rats, physical training induces important metabolic and hormonal alterations that are associated with an improvement in glucose homeostasis and with an increased activity in the systemic and hippocampus IGF-1 peptide.

Introdução: Evidências apontam que a ingestão exacerbada de frutose pode desencadear distúrbios característicos da síndrome metabólica. Objetivos: Analisar os efeitos da ingestão de dieta rica em frutose sobre aspectos metabólicos de ratos da linhagem Wistar. Adicionalmente, verificar a capacidade aeróbia através da identificação da máxima fase estável de lactato (MFEL). Métodos: Dezesseis ratos foram separados em dois grupos de oito animais: a) controle, alimentados com dieta balanceada, e b) frutose, alimentados com dieta rica em frutose. Foram analisadas a tolerância à glicose (área sob a curva de glicose durante teste de tolerância à glicose), sensibilidade à insulina (taxa de remoção da glicose sérica após sobrecarga exógena de insulina), perfil lipídico sérico e concentração de lactato sanguíneo [lac]s durante exercício na intensidade da MFEL. Resultados: Teste t não pareado (p < 0,05) revelou diferença para a tolerância à glicose e triglicérides, porém não houve diferença na sensibilidade à insulina e na [lac]s. Anova one way com post hoc de Newman-Keuls (p < 0,05) revelou diferença para a cinética da glicose durante o teste de tolerância, mas não para a cinética do lactato durante exercício na MSSL. Conclusão: As alterações fisiológicas provocadas pela dieta rica em frutose e inerentes à síndrome metabólica não prejudicam a capacidade aeróbia de ratos.Palavras-chave: máxima fase estável de lactato, síndrome metabólica, exercício. ABSTRACTIntroduction: Evidence points that exacerbated ingestion of fructose may trigger disturbs characteristic of the metabolic syndrome. Objectives: To analyze the effects of a fructose rich diet on metabolic aspects of Wistar lineage rats. Additionally, to verify the aerobic capacity, through the identification of the maximal lactate steady state (MSSL). Procedures: Sixteen rats were separated in two groups of eight animals: a) Control, fed a balanced diet, and b) fructose, fed a fructose-rich diet. The glucose tolerance, (area under serum glucose during a glucose tolerance test), insulin sensibility (glucose disappearance rate after exogenous insulin administration), serum lipid profile and blood lactate concentration [lac]b during exercise at MSSL intensity, have been analyzed. Results: Non-paired t test (p<0.05) revealed difference between groups in the area under the curve of glucose and serum triglycerides, no difference in insulin sensibility or in [lac]b was detected, though. One-way ANOVA with Newman Keuls post hoc revealed difference in the glucose kinetics during tolerance test, but not in the lactate kinetics during the MSSL. Conclusion: The physiological alterations promoted by fructose-rich diet and intrinsic to the metabolic syndrome do not harm the aerobic capacity of rats.

Newborn rats (6 days old) received alloxan intraperitoneally (A= 250 mg/kg b.w). Rats injected with vehicle (citrate buffer) were used as controls (C). After weaning, half of the animals were submitted to 1 hour/day, 5 days/week swimming and with supporting overload of 5% b.w. At 28 days, no signifi cant differences were found among the groups in fasting glycemia and insulinemia. At 60 days, the fasting glycemia (30 min after oral glucose administration) was higher in alloxan than in controls groups and lower in the alloxan group submitted to training than in the correspondent sedentary group. The glucose tolerance of the alloxan rats was reduced in comparison to controls, both at 28 and 60 days, since the area under the blood glucose curve during the OGTT was higher in the alloxan than in the control. No difference was found among the groups both at 28 and 60 days in the HOMA index. However, a slight reduction was observed in the values of the trained groups suggesting slightly increased insulin sensitivity in the animals. These results suggest that this diabetes mellitus animal model presents interesting characteristics for the study of the role of the physical exercise in diabetes outcome.

Background:  Animal models appear well‐suited for studies into the role of exercise in the prevention of non‐insulin‐dependent diabetes mellitus (NIDDM). The aim of the present study was to analyze glucose homeostasis and blood lactate during an exercise swimming test in rats treated with alloxan during the neonatal period and/or fed a high calorie diet from weaning onwards. Methods:  Rats were injected with alloxan (200 mg/kg, i.p.) or vehicle (citrate buffer) at 6 days of age. After weaning, rats were divided into four groups and fed either a balanced diet or a high‐caloric diet as follows: C, control group (vehicle + normal diet); A, alloxan‐treated rats fed the normal diet; H, vehicle‐treated rats fed the high‐caloric diet; and HA, alloxan‐treated rats fed the high‐caloric diet. Results:  Fasting serum glucose levels were higher in groups A and AH compared with the control group. The Homeostatic Model Assessment index varied in the groups as follows: H>A>HA = C. There were no differences in free fatty acids or blood lactate concentrations during the swim test. Conclusions:  Alloxan‐treated rats fed a normal or high‐caloric diet have the potential to be used in studies analyzing the role physical exercise plays in the prevention of NIDDM.

Background: Ninety 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.

A incidência de obesidade vem crescendo entre a população mundial, levando a inúmeras complicaçõe,s como risco de doenças crônico-degenerativas. Por outro lado, o exercício físico tem sido empregado isoladamente ou em associação a dieta, no tratamento dessa doença. Assim, pesquisas envolvendo exercício são imprescindíveis para evolução no tratamento e controle da obesidade. O objetivo deste estudo foi identificar a intensidade de exercício equivalente à transição metabólica aeróbio-anaeróbia em ratos Wistar obesos de ambos os gêneros, por tratamento com glutamato monossódico (MSG), utilizando o protocolo de máxima fase estável de lactato (MFEL). Para isso, foram testados 40 ratos adultos subdivididos em quatro grupos com 10 animais cada um: controle machos, controle fêmeas, obeso machos e obeso fêmeas. Depois de adequada adaptação (três semanas) ao exercício em meio líquido (31 ± 1ºC) os animais foram submetidos a teste de natação (25 min) suportando sobrecargas contínua e aleatória correspondentes a 4,5 -5,0 -5,5 -6,0 e 6,5% do peso corporal (PC), com intervalo de 72 horas entre elas. Os animais dos grupos obesos tiveram aumentos no peso do tecido adiposo subcutâneo, mesentérico e retroperitonial em relação aos grupos controle. O índice de Lee foi maior nos animais obesos em comparação com os controles. Foi possível identificar a MFEL a 6,0% do PC nos dois grupos obesos. Para o grupo controle fêmea, a MFEL esteve por volta de 5,0% do PC enquanto que nos controle macho a 4,5% do PC. Desse modo pode-se concluir que a obesidade induzida por MSG interfere na cinética de lactato durante o exercício em ambos os sexos, alterando a intensidade de esforço referente à transição metabólica.Palavras-chave: obesidade, capacidade aeróbia, hipotálamo. ABstrActThe 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.Keywords: obesity, aerobic capacity, hypothalamus. introdUÇÃo A obesidade é provavelmente uma das enfermidades mais antigas que acometem o hom...

RESUMoSão raros os estudos que associam indicadores de capacidade aeróbia e os substratos produzidos pelo metabolismo muscular em ratos. Dessa forma, o objetivo do presente estudo foi verificar o efeito do treinamento de corrida em duas diferentes intensidades sobre a capacidade aeróbia e a produção de lactato pelo músculo sóleo isolado de ratos. Ratos Wistar (90 dias) tiveram a transição metabólica aeróbio-anaeróbia determinada pelo teste de máxima fase estável de lactato (MFEL). Em seguida, os ratos foram treinados 40 minutos/dia, cinco dias/semana, na velocidade equivalente à MFEL (TT) ou 5% superior a essa (TS), por oito semanas. Como controles foram usados ratos mantidos sedentários (S). Ao final, todos os animais foram sacrificados para análise da produção de lactato pelo músculo sóleo isolado. No inicio do experimento, a maior parte dos animais obteve a MFEL na velocidade de 25m/min à concentração de 4,38 ± 0,22mmol/L sanguínea de lactato. Ao final do experimento, a maior parte dos ratos treinados na TT apresentou MFEL na velocidade de 25m/min, à concentração sanguínea de lactato 3,10 ± 0,27mmol/L. A maioria dos treinados TS teve MFEL na velocidade de 25m/min à concentração sanguínea de lactado de 3,36 ± 0,62mmol/L. Os sedentários mostraram a MFEL na velocidade de 20m/min à concentração sanguínea de lactato de 4,83 ± 0,67mmol/L. A produção de lactato (µmol/g.h) pelo músculo sóleo isolado foi menor no grupo TS (3,83 ± 0,62) do que nos demais (S 4,31 ± 0,58 e TT 4,71 ± 0,39). A partir dos resultados obtidos no presente estudo, pode-se concluir que o treinamento aeróbio evitou a deterioração do condicionamento aeróbio imposta pelo avanço da idade e que o treinamento físico na intensidade superior à MFEL reduziu a produção muscular de lactato.Palavras-chave: limiar anaeróbio, glicogênio, exercício físico. aBStRaCtThere are few studies that associate indicators of aerobic capacity and the substrates produced by the muscular metabolism in rats. The aim of the present study was to analyze the effects of physical training in different intensities on the aerobic capacity and lactate production by the isolated soleus muscle of Wistar rats (90 days) that had the aerobic/anaerobic metabolic transition determined by the Maximal Lactate Steady State Test (MLSS). Subsequently, the rats were trained 40 minutes/day, 5 days/week, in the speed equivalent to MLSS (MT) or 5% above it (AT), for 8 weeks. Rats maintained sedentary (S) were used as controls. At the end, all rats were sacrificed for analysis of lactate production by the isolated soleus muscle. The main results were: in the beginning of the experiment, in most of the rats the MLSS was obtained in the speed of 25m/min, to the concentration of 4.38+0.22mmol/L of blood lactate. At the end of the experiment, most of the rats trained at the MLSS intensity presented MLSS in the speed of 25m/min, to the concentration of 3.10+0.27 mmol/L of blood lactate. Most of the animals trained above-MLSS had MLSS in the speed of 25m/min, to the concentration of 3.36+0.62 mmol/L of bl...

RESUMOO estudo objetivou determinar o limiar anaeróbio (LAn) em teste progressivo de natação e corrida para ratos, por dois métodos matemáticos: concentração fixa de lactato e bissegmentação da curva lactacidêmica. Foram avaliados 19 ratos nadadores e 29 corredores, submetidos a protocolos progressivos com estágios de 5 minutos e coletas de sangue ao final dos estágios. O LAn foi obtido por dois métodos: ajuste exponencial e determinação por concentração fixa de lactato (4,0; 4,5, 5,0 e 5,5mmol/L) e inspeção visual da inflexão da curva lactacidêmica, seguida por bissegmentação das retas de regressão. As intensidades obtidas foram comparadas por ANOVA one-way (P<0,05). Para natação, curvas lactacidêmicas não foram satisfatórias, sendo a melhor análise executada por concentração fixa de lactato a 5,5mmol/L (carga 4,2±0,1%pc). A bissegmentação foi possível com 67,2% dos ratos corredores (LAn=21,1±0,9m/min), o que sugere ser esse método mais adequado para determinação do LAn de ratos nesse exercício.Palavras-chave: Teste progressivo. Limar anaeróbio.