Standard short-term diet ameliorates the lipid profile altered by a fructose-rich diet in rats.

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.

Ectoparasites and endoparasites of fish form networks with different structures.

Hosts and parasites interact with each other in a variety of ways, and this diversity of interactions is reflected in the networks they form. To test for differences in interaction patterns of ecto- and endoparasites we analysed subnetworks formed by each kind of parasites and their host fish species in fish-parasite networks for 22 localities. We assessed the proportion of parasite species per host species, the relationship between parasite fauna composition and host taxonomy, connectance, nestedness and modularity of each subnetwork (n = 44). Furthermore, we evaluated the similarity in host species composition among modules in ecto- and endoparasite subnetworks. We found several differences between subnetworks of fish ecto- and endoparasites. The association with a higher number of host species observed among endoparasites resulted in higher connectance and nestedness, and lower values of modularity in their subnetworks than in those of ectoparasites. Taxonomically related host species tended to share ecto- or endoparasites with the same interaction intensity, but the species composition of hosts tended to differ between modules formed by ecto- and endoparasites. Our results suggest that different evolutionary and ecological processes are responsible for organizing the networks formed by ecto- and endoparasites and fish.

Non-exhaustive test for aerobic capacity determination in running rats.

A simple and applicable method for non-exhaustive aerobic evaluation in running rats is described. Wistar rats were submitted to running test at different velocities (10, 15, 20, 25 m/min) with 48 h recovery among them. At each velocity, the rats ran two bouts of 5 min with 2 min of rest between bouts. Blood samples were collected at the end of each bout for lactate determination. For each intensity, delta lactate was calculated and using deltas obtained by four tests, an individual linear interpolation was plotted. The y-intercept of linear interpolation was the "null delta lactate" equivalent to the critical velocity (CV). To verify the lactate stabilization at CV, the animals were submitted to 25 min of continuous exercise (15, 20, 25 m/min), with blood collection every 5 min. The estimated CV was 16.6 +/- 0.7 m/min, with significant linear regressions (R = 0.90 +/- 0.03). The rats presented maximal lactate steady state (MLSS) at 3.9 +/- 0.4 mmol/L, at 20 m/min. The CV was less than MLSS but significantly correlated with this parameter (r = 0.78). This non-exhaustive test seems to be valid for the aerobic evaluation of sedentary rats and this protocol underestimates the MLSS in 20%. This test seems to be the interesting method for the evaluation of rats submitted to acute exercise or physical training.

Long-term physical training increases liver IGF-I in diabetic rats.

Diabetes reduces the serum levels of insulin-like growth factor-I (IGF-I) and physical training may prevent this reduction. Almost all circulating IGF-I is produced and secreted by the liver. To examine the influence of moderate physical training on liver IGF-1 levels in diabetes, male Wistar rats were given a single dose of alloxan (30 mg/kg b.w.) to induce diabetes and then randomly allocated to sedentary or trained groups. The training protocol consisted of a 1h swimming session/day, five days/week for eight weeks with a load corresponding to 5% of the body weight. These two groups were compared with sedentary or trained non-diabetic rats (controls). A subcutaneous insulin tolerance test (ITT) was performed at the 6th week of experiment. At the end of the training period, the rats in all groups were sacrificed and blood was collected for the quantification of hematocrit and serum glucose, insulin, triglycerides, albumin, GH and IGF-1. Skeletal muscle and hepatic glycogen levels and hepatic triglyceride, protein, DNA and IGF-I concentrations were also determined. Diabetes reduced the serum insulin, GH and IGF-I concentrations, and the hepatic protein/DNA ratio and IGF-I concentrations, but increased serum glucose and triglyceride levels. Serum glucose removal during ITT was increased in the trained diabetic animals compared to sedentary control. Physical training reduced the serum glucose and triglyceride levels but increased the muscle glycogen content and restored the hepatic protein/DNA ratio and serum and hepatic IGF-I in diabetic rats. In conclusion, long-term chronic exercise improved the metabolic state and attenuated the reduction in serum and hepatic IGF-I concentrations caused by diabetes.

Effects of swimming training on bone mass and the GH/IGF-1 axis in diabetic rats.

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.

First record of the bat Mimon crenulatum (E. Geoffroy, 1801) (Mammalia: Chiroptera) in the state of Rio de Janeiro, Southeastern Brazil.

The present study reports an extension of the geographic range of the phyllostomid bat Mimon crenulatum. This is the first record of this species in the state of Rio de Janeiro, Southeastern Brazil. Bats were captured in two conservation units of the Atlantic Forest. Data on the ecology and morphometry of the individuals are presented and compared with data recorded for other localities. The occurrence of this bat species in the region, though new, is consistent with information on its natural history found in the literature.

First record of the bat Mimon crenulatum (E. Geoffroy, 1801) (Mammalia: Chiroptera) in the state of Rio de Janeiro, Southeastern Brazil

O presente estudo relata uma extensão da distribuição geográfica do morcego filostomídeo Mimon crenulatum. Este é o primeiro registro desta espécie para o Estado do Rio de Janeiro, Sudeste do Brasil. Os morcegos foram capturados em duas unidades de conservação de Mata Atlântica de baixada. Dados sobre ecologia e morfometria são apresentados, e comparados a dados registrados para outras localidades. A ocorrência desta espécie de morcego na região, apesar de nova, é consistente com informações sobre sua história natural presentes na literatura.

Proteasome activity is altered in skeletal muscle tissue of tumour-bearing rats a leucine-rich diet.

Leucine can modulate skeletal muscle metabolism by enhancing protein synthesis and decreasing proteolysis. In this study, we investigated the effects of leucine on the ubiquitin-proteasome system in skeletal muscle of pregnant tumour-bearing rats fed a leucine-rich diet. Pregnant Wistar rats were distributed into three groups that were fed a semi-purified control diet (C, control; W, Walker tumour-bearing; P, pair-fed) and three other groups of pregnant rats fed a semi-purified leucine-rich diet (L, leucine; WL, Walker tumour-bearing; PL, pair-fed). The tumour-bearing rats were injected subcutaneously with a suspension of Walker 256 tumour cells. Protein synthesis and degradation were measured in gastrocnemius muscle; the total protein content and tissue chymotrypsin-like and alkaline phosphatase enzyme activities were also determined. Muscle protein extracts were run on SDS-PAGE to assess the expression of the myosin heavy chain (MHC), 20S alpha proteasome subunit, 19S MSSI ATPase regulator subunit and 11S alpha subunit. Although tumour growth decreased the incorporation of [3H]-Phe, the concomitant feeding of a leucine-rich diet increased the rate of protein synthesis. Muscle proteolysis in both tumour-bearing groups was increased more than in the respective control groups. Conversely, the leucine-rich diet caused less protein breakdown in the WL group than in the W group. Only the W group showed a significant reduction (71%) in the myosin content. In WL rats, the 20S proteasome content (32 kDa band) was reduced, while the expression of the 19S subunit was 3-fold less than in the W group and the 11S proteasome subunit reduced, to around 32% less than in the W group. These findings clearly indicate that leucine can stimulate protein synthesis and inhibit protein breakdown in pregnant rats, probably by modulating the activation of the ubiquitin-proteasome system during tumour growth.

Evaluation of a protein deficient diet in rats through blood oxidative stress biomarkers.

Protein malnutrition leads to functional impairment in several organs, which is not fully restored with nutritional recovery. Little is known about the role of oxidative stress in the genesis of these alterations. This study was designed to assess the sensitivity of blood oxidative stress biomarkers to a dietary protein restriction. Male Wistar rats were divided into two groups, according to the diet fed from weaning (21 days) to 60 day old: normal protein (17% protein) and low protein (6% protein). Serum protein, albumin, free fatty acid and liver glycogen and lipids were evaluated to assess the nutritional status. Blood glutathione reductase (GR) and catalase (CAT) activities, plasma total sulfhydryl groups concentration (TSG) as well as plasma thiobarbituric acid reactive substances (TBARs) and reactive carbonyl derivatives (RCD) were measured as biomarkers of the antioxidant system and oxidative damage, respectively. The glucose metabolism in soleus muscle was also evaluated as an index of stress severity imposed to muscular mass by protein malnutrition. No difference was observed in muscle glucose metabolism or plasma RCD concentration between both groups. However, our results showed that the low protein group had higher plasma TBARs (62%) concentration and lower TSG (44%) concentration than control group, indicating increased reactive oxygen species production in low protein group. The enhancement of erythrocyte GR (29%) and CAT (28%) activities in this group also suggest an adaptation to the stress generated by the protein deficiency. Taken together, the results presented here show that the biomarkers used were able to reflect the oxidative stress level induced by this specific protein deficient diet.

Determination of anaerobic threshold in rats using the lactate minimum test.

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.

Determination of anaerobic threshold in rats using the lactate minimum test

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 percent 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 percent 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 percent 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

The monosodium glutamate (MSG) obese rat as a model for the study of exercise in obesity.

Obesity is an increasing problem in several countries, leading to health problems. Physical exercise, in turn, can be used effectively by itself or in combination with dietary restriction to trigger weight loss. The present study was designed to evaluate the effects of aerobic exercise training on lipid profile of obese male Wistar rats in order to verify if this model may be of value for the study of exercise in obesity. Obesity was induced by MSG administration (4 mg/g, each other day, from birth to 14 days old) After 14 from drug administration, the rats were separated into two groups: MSG-S (sedentary) and MSG-T (exercise trained). Exercise training consisted in 1 h/day, 5 days/week, with an overload of 5% bw, for 10 weeks. Rats of the same age and strain, receiving saline at birth, were used as control (C), and subdivided into two groups: C-S and C-T. At the end of the experimental period, MSG-T and C-T rats showed similar blood lactate and muscle glycogen responses to exercise training and acute exercise. MSG-S rats showed significantly higher carcass fat, serum triacylglycerol, serum insulin and liver total fat than C-S rats. On the other hand, MSG-T rats had lower carcass fat, serum triacylglycerol and liver total fat than MSG-S rats. There were no statistical differences in food intake and serum free fatty acids among the groups studied. These data indicate that this model may be of value for the study of exercise effects on tissue and circulating lipid profile in obesity.

Serum electrolyte and total protein alterations in Pantaneiro horse during long distance exercise

Blood samples were taken from eight Pantaneiro horses during a 76Km endurance ride. The horses were divided into two groups: 1- four horses kept on native pasture, without working and with no supplementation during one month before the ride, 2- four horses kept on native pasture with supplementation and submitted to work during one month before the ride. Serum concentration of total protein, albumin, sodium, potassium, chloride, calcium and phosphorus were measured. Samples were taken before the ride (preride), during the mid point (midride), at the end of the ride (postride) and after a 30-minute recovery period (rest). Sweat samples were collected from five horses at the end of the ride to measure sodium, potassium, and chloride. In the groups, there was a significant decrease in calcium and potassium, and an increase in sodium and phosphorus during the ride. Heart rate values after 30 minutes of rest indicated a good recovery response

Effect of a leucine-supplemented diet on body composition changes in pregnant rats bearing Walker 256 tumor

Cancer patients present high mobilization of host protein, with a decrease in lean body mass and body fat depletion occurring in parallel to neoplastic growth. Since leucine is one of the principal amino acids used by skeletal muscle for energy, we investigated the changes in body composition of pregnant tumor-bearing rats after a leucine-supplemented diet. Sixty pregnant Wistar rats divided into six groups were fed a normal protein diet (18 percent, N) or a leucine-supplemented diet (3 percent L-leucine, L). The pregnant groups were: control (CN), Walker 256 carcinoma-bearing rats (WN), control rats pair-fed with tumor-bearing rats (pfN), leucine-supplemented (CL), leucine-supplemented tumor-bearing (WL), and leucine-supplemented rats pair-fed with tumor-bearing rats (pfL). At the end of pregnancy, all animals were sacrificed and body weight and tumor and fetal weight were determined. The carcasses were then analyzed for water, fat and total, collagen and non-collagen nitrogen content. Carcass weight was reduced in the WN, WL, pfN and pfL groups compared to control. The lean body mass and total carcass nitrogen were reduced in both tumor-bearing groups. Despite tumor growth and a decrease in fetal weight, there was a slight decrease in collagen (7 percent) and non-collagen nitrogen (8 percent) in the WL group compared with the WN group which showed a decrease of 8 and 12 percent, respectively. Although the WL group presented severe tumor growth effects, total carcass nitrogen and non-collagen nitrogen were particularly higher in this leucine-supplemented group compared to the WN group. These data suggest that the leucine-supplemented diet had a beneficial effect, probably attenuating body wasting

Effects of protein malnutrition on glucose tolerance in rats with alloxan-induced diabetes

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) perfomed before and after a single dose of alloxan adminsitered to rats fed a 25 percent or a 6 percent 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 percent protein diet (81 percent) than among those fed the 6 percent protein diet (42 percent). During the GTT performed before alloxan adminsitration the serum glucose levels of the rats fed the 6 percent protein diet were not found to be significantly different from those of rats fed the 25 percent 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 adminsitration) 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 percent protein diet than in those fed the 25 percent protein diet but caused glucose intolerance during the oral GTT in both groups. Thus, it seems that feeding a 6 percent protein diet to rats offers only partial protection against the toxic effects of alloxan

Effects of intrauterine and postnatal protein-calorie malnutrition on metabolic adaptations to exercise in young rats

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 percent) casein-based diet prepared in the laboratory during pregnancy and lactation. Control rats received and isocaloric diet containing 25 percent 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 gycogen 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 malnutrtion improved muscle gycogen storage but this substrate was broken down to a greater extent in response to exerceise. 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

Effect of exercise during pregnancy and dam age on maternal blood chemistry and fetal growth

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 j/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 and control rats of the same age and physiological status (YCNP+4.1 ñ 0.2; YCP = 2.7 ñ 0.9; YTNP + 4.9 ñ 0.8; YTP = 2.7 ñ 0.4; ACNP = 6.1 ñ 0.6; ACP = 3.1 ñ 0.8; ATNP = 6.6 ñ 0.8; ATP = 2.2 ñ 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

Effect of maternal exercise during pregnancy on maternal body components and fetal growth in young and adult rats

In order investigate the effects of exercise training on maternal adiposty 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 1h/day, 5 day/week throughout pregnancy or for a 22-day period (non-pregnant rats). Physical activity during 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. Exercice 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 reults 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. Conterregulatory mechanisms during pregnancy and exercice training result in increased food efficiency which probably preserves both maternal and pup metabolism

Effects of protein-calorie malnutrition on endocrine pancreatic function in young preganant rats

Oral glucose tolerance test (GTT), insulin secretion after Oral glucose load and the insulin to glucose ratio (I/G) during GTT were measusred 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 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

Maternal adaptations for fetal growth in young malnourished rats

Carcass composition and serum free fatty acids were determined in young (45 days old) control and malnourished (25 and 6% protein diet, respectively) pregnant rats. Pregnant rats were sacrificed shortly after parturition and nonpregnant rats on the 22nd day of experiment. Carcas fat content increased in control pregnant rats. This alteration was not seen in the pregnant malnourished rats. Serum free fatty acids and pup bith weight were lower for malnourished than for control mothers. No significant difference was pbserved in carcass protein of Na+ and K+ ccontent among rats of all. These data appear to indicate that the inability to accumulate fat in the carcass and the preservacion 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