Carol Góis Leandro

A program of moderate physical training for Wistar rats based on maximal oxygen consumption.

Moderate physical training is often associated with improved cardiorespiratory fitness in athletes and the general population. In animals, studies are designed to investigate basic physiology that could be invasive and uncomfortable for humans. The standardization of an exercise training protocol for rats based on maximal consumption of oxygen (&OV0312;O2max) is needed. This study validated a program of moderate physical training for Wistar rats based on &OV0312;O2max determined once a week. A 10-stage treadmill running test was developed to measure &OV0312;O2max through an indirect, open circuit calorimeter. Thirty male Wistar rats (210–226 g) were randomly assigned to either a nontrained group or a trained group. The animals were evaluated weekly to follow their &OV0312;O2max during 8 weeks of moderate training and to adjust the intensity of the protocol of training. The soleus muscle was removed for determination of citrate synthase activity. Trained animals maintained their values of &OV0312;O2max during a moderate running training and showed a significant less body weight gain. An increase of 42% in citrate synthase activity of the soleus muscle from trained rats was found after the training program. Our study presents a protocol of moderate physical training for Wistar rats based on &OV0312;O2max. Peripheral adaptations such as the values of citrate synthase activity also responded to the moderate training program imposed as observed for &OV0312;O2max. Other studies can use our protocol of moderate training to study the physiologic adaptations underlying this specific intensity of training. It will provide support for study with humans.

Can physical exercise during gestation attenuate the effects of a maternal perinatal low-protein diet on oxygen consumption in rats?

A protocol of physical exercise, based on maximal oxygen uptake , for female rats before and during pregnancy was developed to evaluate the impact of a low‐protein diet on oxygen consumption during gestation and growth rate of the offspring. Virgin female Wistar rats were divided into four groups as follows: untrained (NT, n= 5); trained (T, n= 5); untrained with low‐protein diet (NT+LP, n= 5); and trained with low‐protein diet (T+LP, n= 5). Trained rats were submitted to a protocol of moderate physical training on a treadmill over a period of 4 weeks (5 days week−1 and 60 min day−1, at 65% of ). At confirmation of pregnancy, the intensity and duration of the exercise was reduced. Low‐protein groups received an 8% casein diet, and their peers received a 17% casein diet. The birth weight and growth rate of the pups up to the 90th day were recorded. Oxygen consumption , CO2 production and respiratory exchange ratio (RER) were determined using an indirect open‐circuit calorimeter. Exercise training increased by about 20% when compared with the initial values (45.6 ± 1.0 ml kg−1 min−1). During gestation, all groups showed a progressive reduction in the resting values. Dams in the NT+LP group showed lower values of resting than those in the NT group. The growth rate of pups from low‐protein‐fed mothers was around 50% lower than that of their respective controls. The T group showed an increase in body weight from the 60th day onwards, while the NT+LP group presented a reduced body weight from weaning onwards. In conclusion, physical training attenuated the impact of the low‐protein diet on oxygen consumption during gestation and on the growth rate of the offspring.

Maternal low-protein diet-induced delayed reflex ontogeny is attenuated by moderate physical training during gestation in rats.

We evaluated the effects of moderate- to low-intensity physical training during gestation on reflex ontogeny in neonate rats whose mothers were undernourished. Virgin female Wistar rats were divided into four groups as follows: untrained (NT, n 7); trained (T, n 7); untrained with a low-protein diet (NT+LP, n 7); trained with a low-protein diet (T+LP, n 4). Trained rats were subjected to a protocol of moderate physical training on a treadmill over a period of 4 weeks (5 d/week and 60 min/d, at 65 % of VO₂max). After confirming the pregnancy, the intensity and duration of the exercise were reduced. Low-protein groups were provided with an 8 % casein diet, and controls were provided with a 17 % casein diet. Their respective offspring were evaluated (during the 10th-17th days of postnatal life) in terms of physical feature maturation, somatic growth and reflex ontogeny. Pups born to mothers provided with the low-protein diet during gestation and lactation showed delayed physical feature and reflex maturation and a deficit in somatic growth when compared with controls. However, most of these deficiencies were attenuated in pups of undernourished mothers undergoing training. In conclusion, physical training during gestation attenuates the effects of perinatal undernutrition on some patterns of maturation in the central nervous system during development.

Maternal Protein Restriction Increases Respiratory and Sympathetic Activities and Sensitizes Peripheral Chemoreflex in Male Rat Offspring

BACKGROUND Maternal protein restriction in rats increases the risk of adult offspring arterial hypertension through unknown mechanisms. OBJECTIVES The aims of the study were to evaluate the effects of a low-protein (LP) diet during pregnancy and lactation on baseline sympathetic and respiratory activities and peripheral chemoreflex sensitivity in the rat offspring. METHODS Wistar rat dams were fed a control [normal-protein (NP); 17% protein] or an LP (8% protein) diet during pregnancy and lactation, and their male offspring were studied at 30 d of age. Direct measurements of baseline arterial blood pressure (ABP), heart rate (HR), and respiratory frequency (Rf) as well as peripheral chemoreflex activation (potassium cyanide: 0.04%) were recorded in pups while they were awake. In addition, recordings of the phrenic nerve (PN) and thoracic sympathetic nerve (tSN) activities were obtained from the in situ preparations. Hypoxia-inducible factor 1α (HIF-1α) expression was also evaluated in carotid bifurcation through a Western blotting assay. RESULTS At 30 d of age, unanesthetized LP rats exhibited enhanced resting Rf (P = 0.001) and similar ABP and HR compared with the NP rats. Despite their similar baseline ABP values, LP rats exhibited augmented low-frequency variability (∼91%; P = 0.01). In addition, the unanesthetized LP rats showed enhanced pressor (P = 0.01) and tachypnoeic (P = 0.03) responses to peripheral chemoreflex activation. The LP rats displayed elevated baseline tSN activity (∼86%; P = 0.02) and PN burst frequency (45%; P = 0.01) and amplitude (53%; P = 0.001) as well as augmented sympathetic (P = 0.01) and phrenic (P = 0.04) excitatory responses to peripheral chemoreflex activation compared with the NP group. Furthermore, LP rats showed an increase of ∼100% in HIF-1α protein density in carotid bifurcation compared with NP rats. CONCLUSION Sympathetic-respiratory overactivity and amplified peripheral chemoreceptor responses, potentially through HIF-1α-dependent mechanisms, precede the onset of hypertension in juvenile rats exposed to protein undernutrition during gestation and lactation.

Permanent Deficits in Handgrip Strength and Running Speed Performance in Low Birth Weight Children

The main goal of this study was to verify the influence of low birth weight (LBW) on the physical fitness of children aged 7–10 years. The comparisons were subsequently adjusted for chronological age, gender, physical activity (PA), and body composition.

Mecanismos adaptativos do sistema imunológico em resposta ao treinamento físico

O treinamento fisico, de intensidade moderada, melhora os sistemas de defesa, enquanto que o treinamento intenso causa imunossupressao. Os mecanismos subjacentes estao associados a comunicacao entre os sistemas nervoso, endocrino e imunologico, sugerindo vias autonomicas e modulacao da resposta imune. Celulas do sistema imune, quando expostas a pequenas cargas de estresse, desenvolvem mecanismo de tolerância. Em muitos tecidos tem-se demonstrado que a resposta a situacoes agressivas parece ser atenuada pelo treinamento fisico aplicado previamente, isto e, o treinamento induz tolerância para situacoes agressivas/estressantes. Nesta revisao sao relatados estudos sugerindo os mecanismos adaptativos do sistema imunologico em resposta ao treinamento fisico.

Perinatal undernutrition stimulates seeking food reward.

Experiments in animals have revealed that perinatal nutritional restriction, which manifests in adulthood, increases food intake and preference for palatable foods. Considering this, we aimed to evaluate the effects of perinatal malnutrition on hedonic control of feeding behavior. In this study, we divided Wistar rats into two groups according to the diet provided to their mothers during pregnancy and lactation: the control group (diet with 17% casein) and low‐protein group (diet with 8% casein). We assessed the animals’ motivational behavior in adulthood by giving them a stimulus of food reward. We also assessed their neuronal activation triggered by the stimulus of palatable food using FOS protein labeling of neurons activated in the caudate putamen, paraventricular, dorsomedial, ventromedial, and lateral hypothalamic nuclei and amygdala. Evaluation of body weight in malnourished animals showed reduction from the 6th day of life until adulthood. Analysis of feeding behavior revealed that these animals were more motivated by food reward, but they had delays during learning of the task. This finding correlated with the number of c‐FOS‐immunoreactive neurons, which indicated that malnourished animals had an increase in the number of neurons activated in response to the palatable diet, especially in the amygdala and caudate putamen. The study therefore confirmed our hypothesis that early nutritional insults promote changes in encephalic control mechanisms, especially those related to food intake and search for reward.

The effects of palmitic acid on nitric oxide production by rat skeletal muscle: mechanism via superoxide and iNOS activation.

Background: Increased plasma concentrations of free fatty acids (FFA) can lead to insulin resistance in skeletal muscle, impaired effects on mitochondrial function, including uncoupling of oxidative phosphorylation and decrease of endogenous antioxidant defenses. Nitric oxide (NO) is a highly diffusible gas that presents a half-life of 5-10 seconds and is involved in several physiological and pathological conditions. The effects of palmitic acid on nitric oxide (NO) production by rat skeletal muscle cells and the possible mechanism involved were investigated. Methods: Primary cultured rat skeletal muscle cells were treated with palmitic acid and NO production was assessed by nitrite measurement (Griess method) and 4,5-diaminofluorescein diacetate (DAF-2-DA) assay. Nuclear factor-kappa B (NF-ĸB) activation was evaluated by electrophoretic mobility shift assay and iNOS protein content by western blotting. Results: Palmitic acid treatment increased nitric oxide production. This effect was abolished by treatment with NOS inhibitors, L-nitro-arginine (LNA) and L-nitro-arginine methyl esther (L-NAME). NF-ĸB activation and iNOS content were increased due to palmitic acid treatment. The participation of superoxide on nitric oxide production was investigated by incubating the cells with DAF-2-DA in the presence or absence of palmitic acid, a superoxide generator system (X-XO), a mixture of NOS inhibitors and SOD-PEG (superoxide dismutase linked to polyethylene glycol). Palmitic acid and X-XO system increased NO production and this effect was abolished when cells were treated with NOS inhibitors and also with SOD-PEG. Conclusions: In summary, palmitic acid stimulates NO production in cultured skeletal muscle cells through production of superoxide, nuclear factor-kappa B activation and increase of iNOS protein content.

Physical Training Attenuates the Stress-Induced Changes in Rat T-Lymphocyte Function

Backgorund/Aims: Modulations in the immune function by stress are a well-known phenomenon. Acute restraint stress may induce impaired T-lymphocyte responses. Moderate physical training is associated with beneficial effects on immunological functions. We investigated the effects of a moderate physical training on T-lymphocyte function in rats submitted to acute restraint stress. Methods: Thirty male Wistar rats weighing 210–226 g were randomly divided into four groups: non-trained rats (NT, n = 7), and non-trained rats submitted to stress (NT + S, n = 8); trained rats (T, n = 7), and trained rats submitted to stress (T + S, n = 8). Trained rats were submitted to a program of moderate running over a period of 8 weeks. Rats subjected to restraint stress were kept immobilized in glass cylinders (8 cm in diameter and 24 cm long) during 60 min. Plasma corticosterone concentration, peripheral blood leukocyte number, indicators of apoptosis of T lymphocytes in blood and lymphoid organs, and mitogen-induced proliferation of T lymphocytes in lymphoid organs were evaluated. Results: Acute stress exposure raised plasma corticosterone concentration (p < 0.001), but not in previously trained animals. Restraint stress induced an increase in the percentage of lymphocytes in apoptosis, and a decrease in the concanavalin-A-induced proliferation of lymphocytes from the thymus and lymph nodes, and an increase in lymphocytes of the spleen. Neither of these alterations was observed in trained animals submitted to acute restraint stress. Conclusions: Our data confirm that acute restraint stress is associated with changes in T-lymphocyte function. Moreover, moderate physical training attenuates the effects of acute stress by a mechanism that involves the hypothalamic-pituitary-adrenal axis and an increase in tolerance of leukocytes.

Stress/Aggressiveness-Induced Immune Changes Are Altered in Adult Rats Submitted to Neonatal Malnutrition

Background/Aims: Neonatal malnutrition induces metabolic and endocrine changes that have beneficial effects on the neonatal in the short term but, in the longer term, these alterations lead to maladaptations. We investigated the effect of neonatal malnutrition on immune responses in adult rats submitted or not to an aggressiveness test. Methods: Male Wistar rats were distributed to one of two groups according to their mothers’ diet during lactation: the well-nourished group (group C, n = 42, receiving 23% of protein) and the malnourished group (group MN, n = 42, receiving 8% of protein). After weaning, all rats received normoproteic diet. Ninety days after birth, each group was subdivided into three subgroups: control rats (n = 14, respectively), aggressive rats (n = 14, respectively) and rats receiving foot shock (FS; n = 14, respectively). Plasma corticosterone concentration was measured after FS sessions. Leukocyte counts and humoral immunity were evaluated. Results: In neonatal malnourished animals, FS-induced stress reduced plasma corticosterone concentration. Intraspecific aggressiveness induced alterations in leukocyte counts and antibody titers 7 and 15 days after immunization. Neonatal malnourished animals showed no changes in the immune parameters evaluated. Conclusions: Expression of intraspecific aggressiveness activates the immune system. Neonatal malnutrition seems to have a long-lasting effect on components of both neuroendocrine and immune functions.