RESUMO
Markers of metabolic abnormalities are commonly found in rodents fed a fructose-rich diet. The purpose of this study was to determine whether the administration of a short-term standard diet to rats is able to improve the lipid profile altered by a fructose-rich diet. The male pups, immediately after birth, were divided in three groups according to the diet for 90 days. Standard diet: a standard diet for the whole experimental period; fructose (60% fructose-rich diet): fructose-rich diet during the entire experimental period; fructose/standard (FS): fructose-rich diet from the neonatal period up to 60 days of age and standard diet from 60 to 90 days of age. A fructose-rich diet from the neonatal period to 60 days reduced weight gain (P<0.05), as well as the weight of adipose tissues in all the regions analyzed (epididymal, mesenteric, retroperitoneal and posterior subcutaneous), and it altered the lipid profile (elevation of triglycerides, total cholesterol, low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol; P<0.05). When a standard diet was administered after the fructose-rich diet, it was able to partially reverse changes to the lipid profile, as total cholesterol levels were significantly different in all the groups (P<0.05), and triglyceride and VLDL cholesterol levels were similar between the control and FS group. In summary, a fructose-rich diet altered the lipid profile, and a standard diet can partially reverse the changed parameters in short term.
Assuntos
Dislipidemias/dietoterapia , Frutose/efeitos adversos , Adiposidade , Animais , Dislipidemias/etiologia , Feminino , Masculino , Gravidez , Ratos WistarRESUMO
The aim of this study was to examine the influence of moderate swimming training on the GH/IGF-1 growth axis and tibial mass in diabetic rats. Male Wistar rats were allocated to one of four groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD) and trained diabetic (TD). Diabetes was induced with alloxan (35 mg/kg b.w.). The training program consisted of a 1h swimming session/day with a load corresponding to 5% of the b.w., five days/week for six weeks. At the end of the training period, the rats were sacrificed and blood was collected for quantification of the serum glucose, insulin, GH, and IGF-1 concentrations. Samples of skeletal muscle were used to quantify the IGF-1 peptide content. The tibias were collected to determine their total area, length and bone mineral content. The results were analyzed by ANOVA with P<0.05 indicating significance. Diabetes decreased the serum levels of GH and IGF-1, as well as the tibial length, total area and bone mineral content in the SD group (P<0.05). Physical training increased the serum IGF-1 level in the TC and TD groups when compared to the sedentary groups (SC and SD), and the tibial length, total area and bone mineral content were higher in the TD group than in the SD group (P<0.05). Exercise did not alter the level of IGF-1 in gastrocnemius muscle in nondiabetic rats, but the muscle IGF-1 content was higher in the TD group than in the SD group. These results indicate that swimming training stimulates bone mass and the GH/IGF-1 axis in diabetic rats.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/terapia , Hormônio do Crescimento/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Condicionamento Físico Animal , Animais , Densidade Óssea , Diabetes Mellitus Experimental/patologia , Hormônio do Crescimento/sangue , Masculino , Músculo Esquelético/metabolismo , Ratos , Ratos Wistar , Natação , Tíbia/metabolismo , Tíbia/patologiaRESUMO
The break point of the curve of blood lactate vs exercise load has been called anaerobic threshold (AT) and is considered to be an important indicator of endurance exercise capacity in human subjects. There are few studies of AT determination in animals. We describe a protocol for AT determination by the "lactate minimum test" in rats during swimming exercise. The test is based on the premise that during an incremental exercise test, and after a bout of maximal exercise, blood lactate decreases to a minimum and then increases again. This minimum value indicates the intensity of the AT. Adult male (90 days) Wistar rats adapted to swimming for 2 weeks were used. The initial state of lactic acidosis was obtained by making the animals jump into the water and swim while carrying a load equivalent to 50% of body weight for 6 min (30-s exercise interrupted by a 30-s rest). After a 9-min rest, blood was collected and the incremental swimming test was started. The test consisted of swimming while supporting loads of 4.5, 5.0, 5.5, 6.0 and 7.0% of body weight. Each exercise load lasted 5 min and was followed by a 30-s rest during which blood samples were taken. The blood lactate minimum was determined from a zero-gradient tangent to a spline function fitting the blood lactate vs workload curve. AT was estimated to be 4.95 +/- 0.10% of body weight while interpolated blood lactate was 7.17 +/- 0.16 mmol/l. These results suggest the application of AT determination in animal studies concerning metabolism during exercise.
Assuntos
Limiar Anaeróbio/fisiologia , Ácido Láctico/sangue , Condicionamento Físico Animal/fisiologia , Resistência Física/fisiologia , Natação/fisiologia , Animais , Masculino , Ratos , Ratos WistarRESUMO
The present study was designed to evaluate the effects of chronic aerobic exercise (swimming, 1h/day, 5 days/week, with an overload of 5% body weight) on glucose metabolism in obese male Wistar rats. Hypothalamic obesity was induced through administration of monosodium glutamate (MSG) at 4 mg/g of body weight every other day from birth to 14 days old. Fourteen weeks after drug administration, the rats were separated into two groups: MSG-S (sedentary) and MSG-T (swimming for 10 weeks). Rats of the same age and strain, receiving saline in place of MSG, were used as control (C), and subdivided into two groups: C-S and C-T. At the end of the experimental period, an oral glucose tolerance test was performed and serum glucose (AG) and insulin (AI) were evaluated. A constant for serum glucose decrease (Kitt) in response to exogenous insulin was calculated. Soleus muscle strips and adipose tissue samples were incubated and insulin stimulated glucose uptake determined. No differences were observed in AG among the 4 groups. MSG-S rats showed higher Al (418%) and lower Kitt (92.3%) than C-S rats. T-rats showed higher glucose uptake by muscle (224.0%) and adipose tissues (94.1%) than S-rats. Among trained rats, glucose uptake by muscle was higher in MSG-T (5.4%) than in C-T, while the opposite was observed in adipose tissue (39% higher in C-T). Chronic aerobic exercise was able to improve glucose tolerance and reduce insulin resistance in MSG-obese rats. These effects were associated to an increase in glucose uptake by muscle and adipose tissue in response to insulin.
Assuntos
Aditivos Alimentares , Glucose/metabolismo , Insulina/fisiologia , Obesidade/induzido quimicamente , Obesidade/metabolismo , Condicionamento Físico Animal/fisiologia , Glutamato de Sódio , Tecido Adiposo/metabolismo , Tecido Adiposo/fisiologia , Animais , Glicemia/metabolismo , Composição Corporal/fisiologia , Feminino , Teste de Tolerância a Glucose , Ácido Láctico/sangue , Masculino , Músculo Esquelético/metabolismo , Ratos , Ratos Wistar , Aumento de Peso/fisiologiaRESUMO
Protein-calorie malnutrition produces glucose intolerance and reduced insulin release in response to glucose. Rats adapted to low- or high-protein diets show an increased resistance to the diabetogenic action of a single dose of streptozotocin or alloxan. To determine the effects of dietary protein level on pancreatic function, we measured serum glucose levels under basal conditions and during the oral glucose tolerance test (GTT) performed before and after a single dose of alloxan administered to rats fed a 25% or a 6% protein diet for a period of 8 weeks. The incidence of mild hyperglycemia (serum glucose > 250 mg/dl) was greater among the rats fed the 25% protein diet (81%) than among those fed the 6% protein diet (42%). During the GTT performed before alloxan administration the serum glucose levels of the rats fed the 6% protein diet were not found to be significantly different from those of rats fed the 25% protein diet. During the GTT performed after alloxan injection all rats showed intolerance to the substrate (serum glucose > 160 mg/dl 120 min after glucose administration) regardless of whether basal serum glucose was normal or high. In summary, alloxan was less effective in producing basal hyperglycemia in the rats fed the 6% protein diet than in those fed the 25% protein diet but caused glucose intolerance during the oral GTT in both groups. Thus, it seems that feeding a 6% protein diet to rats offers only partial protection against the toxic effects of alloxan.
Assuntos
Diabetes Mellitus Experimental/fisiopatologia , Desnutrição Proteico-Calórica/fisiopatologia , Animais , Glicemia/análise , Proteínas Alimentares/administração & dosagem , Teste de Tolerância a Glucose , Hiperglicemia/fisiopatologia , Masculino , Ratos , Ratos WistarRESUMO
The effect of intrauterine and postnatal protein-calorie malnutrition on the biochemical ability to perform exercise was investigated in young male rats. Malnourished rats were obtained by feeding dams a low-protein (6%) casein-based diet prepared in the laboratory during pregnancy and lactation. Control rats received an isocaloric diet containing 25% protein. The low-protein diet contained additional starch and glucose. At 45 days of age, malnourished rats showed lower body weight, serum protein, albumin and glucose levels, hematocrit values and heart glycogen content but higher circulating free fatty acids and gastrocnemius muscle glycogen than control rats. In response to exercise (50 min of swimming), control rats displayed lower heart, gastrocnemius and liver glycogen levels whereas malnourished rats showed low glycogen levels only in the gastrocnemius muscle. Both control and malnourished rats showed high serum glucose and free fatty acid levels after exercise. In conclusion, protein-calorie malnutrition improved muscle glycogen storage but this substrate was broken down to a greater extent in response to exercise. Malnourished rats were able to perform exercise maintaining high blood glucose levels, as observed in control rats, perhaps as a consequence of the elevated availability of circulating free fatty acids.
Assuntos
Adaptação Fisiológica , Condicionamento Físico Animal , Desnutrição Proteico-Calórica/fisiopatologia , Animais , Proteínas Sanguíneas/análise , Peso Corporal , Feminino , Glicogênio/metabolismo , Hematócrito , Masculino , Gravidez , Complicações na Gravidez , Desnutrição Proteico-Calórica/metabolismo , Ratos , Ratos WistarRESUMO
In order to determine the effect of maternal exercise on maternal nutritional status and fetal growth, young (Y = 45-50 days old) Wistar rats were divided into 4 groups of 5 to 8 animals: control pregnant (CP), control non-pregnant (CNP), exercise-trained (swimming 1 h/day, 5 days/week, for 19 days) pregnant (TP) and exercise-trained non-pregnant (TNP). Four equivalent groups of adult rats (A = 90-100 days old) were also formed. Serum glucose, total protein, albumin, hematocrit and liver glycogen were determined in female rats and pups. There were no statistical differences in serum glucose, total protein and albumin levels, litter size or birth weight among exercise-trained animals, controls and their respective pups. Hematocrit was significantly lower in pups of exercise-trained young rats than in all other groups (YCP = 38.6 +/- 3.0; YTP = 32.6 +/- 2.1; ACP = 39.0 +/- 2.5; ATP = 39.2 +/- 2.9%). Liver glycogen levels were lower in pregnant than in non-pregnant rats but similar in exercise-trained and control rats of the same age and physiological status (YCNP = 4.1 +/- 0.2; YCP = 2.7 +/- 0.9; YTNP = 4.9 +/- 0.8; YTP = 2.7 +/- 0.4; ACNP = 6.1 +/- 0.6; ACP = 3.1 +/- 0.8; ATNP = 6.6 +/- 0.8; ATP = 2.2 +/- 0.9 mg/100 mg). We conclude that pups of adult female rats are spared from the effects of this kind of exercise training during pregnancy. On the other hand, it appears that maternal adaptations to exercise training in young rats are able to preserve only some aspects of pup metabolism.
Assuntos
Envelhecimento/sangue , Desenvolvimento Embrionário e Fetal/fisiologia , Condicionamento Físico Animal/fisiologia , Prenhez/sangue , Animais , Glicemia/análise , Proteínas Sanguíneas/análise , Feminino , Hematócrito , Glicogênio Hepático/sangue , Gravidez , Ratos , Ratos Wistar , Natação , Fatores de TempoRESUMO
In order to investigate the effects of exercise training on maternal adiposity and fetal development, young Wistar rats (45-50 days old) were divided into four groups: control non-pregnant, control pregnant, exercise-trained non-pregnant and exercise-trained pregnant. Four equivalent groups of adult rats (90-100 days old) were also used. Trained rats swam 1 h/day, 5 day/week throughout pregnancy or for a 22-day period (non-pregnant rats). Physical activity during the entire gestational period reduced weight gain during pregnancy. Both control and trained pregnant rats showed an increase in food intake during the 2nd week of pregnancy and increased food efficiency. Exercise training reduced perirenal fat weight in young and adult pregnant rats. Muscle protein content, litter size and birth weight of pups were similar for control and trained rats. These results indicate that the energy expenditure required during exercise training by both young and adult pregnant rats reduces depot fat and does not seem to alter normal gestation. Counterregulatory mechanisms during pregnancy and exercise training result in increased food efficiency which probably preserves both maternal and pup metabolism.
Assuntos
Tecido Adiposo/anatomia & histologia , Composição Corporal , Desenvolvimento Embrionário e Fetal , Condicionamento Físico Animal , Aumento de Peso , Animais , Ingestão de Energia , Feminino , Gravidez , Ratos , Ratos EndogâmicosRESUMO
In order to evaluate some factors likely to be involved in the maternal and fetal growth impairment due to alimentary protein deficiency, the circulating levels of triiodothyronine (T3) and thyroxine (T4) were studied in 4 young (45-day-old) female rat groups: control and malnourished, both nonpregnant and pregnant; similarly scheduled groups were studied using adult (100-day-old) rats. Circulating levels of T4 were higher in nonpregnant, malnourished young rats than in their corresponding controls. T3 levels were higher in young malnourished animals and lower in adult malnourished animals, nonpregnant or pregnant, as compared to controls. Pups from young malnourished mothers showed significantly lower birth weights than those from controls. The present results suggest that there are age differences in thyroid function, as affected by protein-calorie malnutrition in pregnant and nonpregnant rats. On the other hand, the circulating thyroid hormone levels were not importantly affected by the mother dietary protein restriction under our experimental conditions.
Assuntos
Feto/metabolismo , Distúrbios Nutricionais/metabolismo , Prenhez , Hormônios Tireóideos/sangue , Animais , Peso Corporal , Dieta , Feminino , Idade Gestacional , Gravidez , Ratos , Ratos Endogâmicos , Tiroxina/sangue , Tri-Iodotironina/sangueRESUMO
The effect on reproduction and fetal growth of a protein-deficient diet administration during pregnancy was studied in young and adult rats. Young (50-55 days old) and adult (90-100 days old) pregnant or nonpregnant rats were fed a normal diet (25% protein) or a protein-deficient diet (6% protein) during pregnancy or for a 22-day period (nonpregnant rats). All females were weighed during the experiment and body length measured in the young rats. After parturition, pups were counted, sexed and individually weighed. Litter size, number of stillbirths and presence of body lesions in the neonates were also recorded. Alimentary protein deficiency caused reduction in weight gain during pregnancy and in the postpartum period in young and adult rats. Pups from protein deficient dams weighed less at birth than the pups of control dams, although litter size was unaltered. Pups from young malnourished dams tended to weigh less than those from adult malnourished dams. The incidence of stillbirths was higher in malnourished rats, the highest values occurring in the adult group. These results suggest that alimentary protein deficiency during pregnancy in young rats reduces maternal weight gain, presumably reducing nutrient storage. This may cause fetal/maternal competition for nutrients leading to retardation of both maternal and fetal growth. Growth impairment may be an adaptive process, assuring fetal survival.
Assuntos
Envelhecimento/fisiologia , Complicações na Gravidez/fisiopatologia , Desnutrição Proteico-Calórica/fisiopatologia , Ratos Endogâmicos/anatomia & histologia , Reprodução/fisiologia , Animais , Biometria , Peso ao Nascer , Peso Corporal/fisiologia , Dieta , Modelos Animais de Doenças , Feminino , Morte Fetal , Tamanho da Ninhada de Vivíparos/fisiologia , Masculino , Gravidez , RatosRESUMO
Oral glucose tolerance test (GTT), insulin secretion after oral glucose load and the insulin to glucose ratio (I/G) during GTT were measured in young (45-50 days old) pregnant and non-pregnant rats fed a normal (25%) or low (6%) protein diet during pregnancy or for a 22-day period. Fasting blood glucose was lower in protein-deficient rats and basal plasma insulin was higher in pregnant control rats than in non-pregnant controls. Protein-deficient rats were intolerant to the oral glucose load. The I/G ratio during GTT was higher in control pregnant rats than in other rats. These results show that young malnourished pregnant rats are glucose intolerant and do not show pregnancy hyperinsulinemia probably as a result of decreased pancreatic capacity to release insulin in response to stimulation.
Assuntos
Glicemia/análise , Insulina/sangue , Ilhotas Pancreáticas/fisiopatologia , Desnutrição Proteico-Calórica/sangue , Animais , Feminino , Teste de Tolerância a Glucose , Gravidez , Desnutrição Proteico-Calórica/fisiopatologia , Ratos , Ratos EndogâmicosRESUMO
Carcass composition and serum free fatty acids were determined in young (45 days old) control and malnourished (25 and 6% protein diet, respectively) pregnant and nonpregnant rats. Pregnant rats were sacrificed shortly after parturition and nonpregnant rats on the 22nd day of experiment. Carcass fat content increased in control pregnant rats. This alteration was not seen in the pregnant malnourished rats. Serum free fatty acids and pup birth weight were lower for malnourished than for control mothers. No significant difference was observed in carcass protein of Na+ and K+ content among rats of all groups. These data appear to indicate that the inability to accumulate fat in the carcass and the preservation of carcass protein at nonpregnant levels during pregnancy may be important factors involved in the genesis of the low birth weight seen in the pups of young malnourished rats, presumably reducing the availability of nutrient supplies for fetal growth.