Responses of blood lactate concentration in aerobic and anaerobic training protocols at different swimming exercise intensities in rats

A swimming periodized experimental training model in rats in which different training protocols (TP) were classified in aerobic (A) and anaerobic (AN) intensity levels. The purpose of the present study was to verify if the classification of the TP used in the periodized training experimental model presented the blood lactate concentration [La] response adequate to the aerobic and anaerobic intensities levels. Twenty three male Wistar rats were divided into three groups. Two groups of swimming training (continuous, CT, n = 7, and periodized training, PET, n = 7) rats were evaluated during 5 weeks in eight different TP (TP-1 to TP-8) through the analysis of the [La] response. The third group was the sedentary control (SC, n = 9). The TP were classified in five intensity levels, three aerobic (A-1, A-2, A-3) and two anaerobic (AN-1, AN-2). Analysis of variance (ANOVA one-way, P<0.05) indicated significant differences in the [La] among the TP and among the five intensity levels. All TP of the A-2 and A-3 intensity levels differed from the A-1 and AN-1. The A-1 and AN-1 also differed among them. These findings demonstrate that the TP were classified properly at different levels of aerobic and anaerobic intensities, as based on the [La] response in a way similar to that of high performance swimming with humans. The results offer new perspectives for the study of exercise training in swimming rats at different levels intensity for performance or for health.

Histochemical and ultrastructural analysis of hepatic glycogen and collagen fibers in alloxan-induced diabetic rats submitted to long-term physical training

Alterations in liver functions are common among diabetic patients, and many symptoms in the liver have been reported, including changes in glycogen stores and in the amount of collagen fibers. The practice of physical training and its morphological effects in this organ, however, are scarcely studied. In order to observe the morphological effects of alloxan-induced diabetes and the alterations arising from the practice of long-term chronic physical training in the liver, samples were collected and processed, and then analyzed by means of the histochemical techniques Periodic Acid-Schiff and Picrosirius-Hematoxylin, and ultrastructural cytochemical test of Afzelius. Through evaluation of the tissue, it was observed a drastic reduction in hepatic glycogen stores of sedentary diabetics, recovered in trained diabetic rats. Furthermore, it was detected a decrease in the content of perisinusoidal collagen fibers in the diabetic liver, also recovered due to the development of a training protocol. On ultrastructural level, cytochemical analysis confirmed the loss of glycogen and the recovery obtained by training. In conclusion, the practice of a long-term chronic physical training protocol may be considered an important assistant in the treatment of diabetes, mitigating the occurrence of possible damages to liver tissue. © 2011 Elsevier Ltd.

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.

Morphological changes in the fast vs slow fiber profiles of the urethras of diabetic pregnant rats

Background: This study was undertaken to test the hypothesis that diabetes and pregnancy detrimentally affect the normal function of urethral striated muscles in rats, providing a model for additional studies related to urinary incontinence. The aim of this study was to evaluate morphological alterations in the urethral striated muscles of diabetic pregnant rats. Materials and Methods: Twenty female Wistar rats were distributed into four experimental groups of five rats as follows: virgin, pregnant, diabetic virgin, and diabetic pregnant. Diabetes was induced using streptozotocin administration (40 mg/kg i.v.). The rats were lethally anesthetized, and the urethra and vagina were extracted as a unit. Cryostat sections (6 μm thick) were cut and stained with hematoxylin-eosin, and immunohistochemical procedures were performed and subjected to morphological and semi quantitative analysis. Results: The urethral striated muscle from the diabetic pregnant rats presented with the following variations: thinning and atrophy, disorganization and disruption associated with the colocalization of fast and slow fibers and a steady decrease in the proportion of fast vs slow fibers. Conclusion: Diabetes and pregnancy impair the urethral striated muscle and alter its fiber type distribution. © Copyright G. Marini et al., 2011.

Soybean glycinin (11S) increases HDL-cholesterol in hypercholesterolemic rats

Purpose: The purpose of this paper is to determine the effects of isolated soy glycinin (11S) on lipid metabolism in animals subjected to a hypercholesterolemic diet. Design/methodology/approach: Male Wistar rats were kept in individual cages under appropriate conditions. The animals were divided into three groups (n=9): normal diet (STD) given a diet containing casein as protein source, recommended in AIN-93M; hypercholesterolemic (HC) fed a normal diet with 1 per cent cholesterol and 0.5 per cent cholic acid; and hypercholesterolemic+glycinin (HC+11S), fed a hypercholesterolemic diet, plus 11S soy protein (300 mg/kg/day), dissolved in saline and administered by gavage. After 28 days, the animals were sacrificed and blood and liver removed for biochemical analysis of total cholesterol (TC), HDL-cholesterol (HDL-C) and triglycerides (TG) in the plasma, hepatic TC and TG. Findings: A single daily dose of glycinin given to the hypercholesterolemic group demonstrated its functional role, particularly in raising HDL-C and reducing triglycerides in the liver. Originality/value: This study demonstrates the action of the 11S globulin in soybean as a serum lipid lowering agent, in addition to its nutritional properties, especially in raising the HDL-C. © Emerald Group Publishing Limited.

Experimental hyperthyroidism decreases gene expression and serum levels of adipokines in obesity

Aims. To analyze the influence of hyperthyroidism on the gene expression and serum concentration of leptin, resistin, and adiponectin in obese animals. Main Methods. Male Wistar rats were randomly divided into two groups: control (C)fed with commercial chow ad libitumand obese (OB)fed with a hypercaloric diet. After group characterization, the OB rats continued receiving a hypercaloric diet and were randomized into two groups: obese animals (OB) and obese with 25g triiodothyronine (T3)/100BW (OT). The T3 dose was administered every day for the last 2 weeks of the study. After 30 weeks the animals were euthanized. Samples of blood and adipose tissue were collected for biochemical and hormonal analyses as well as gene expression of leptin, resistin, and adiponectin. Results. T3 treatment was effective, increasing fT3 levels and decreasing fT4 and TSH serum concentration. Administration of T3 promotes weight loss, decreases all fat deposits, and diminishes serum levels of leptin, resistin, and adiponectin by reducing their gene expression. Conclusions. Our results suggest that T3 modulate serum and gene expression levels of leptin, resistin, and adiponectin in experimental model of obesity, providing new insights regarding the relationship between T3 and adipokines in obesity. Copyright © 2012 Renata de Azevedo Melo Luvizotto et al.

Heat shock protein production and immunity and altered fetal development in diabetic pregnant rats

We evaluated associations between the concentrations of heat shock proteins (hsp60 and hsp70) and their respective antibodies, alterations in maternal reproductive performance, and fetal malformations in pregnant rats with hyperglycemia. Mild diabetes (MD) or severe diabetes (SD) was induced in Sprague-Dawley rats prior to mating; non-treated non-diabetic rats (ND) served as controls. On day 21 of pregnancy, maternal blood was analyzed for hsp60 and hsp70 and their antibodies; and fetuses were weighed and analyzed for congenital malformations. Hsp and anti-hsp levels were correlated with blood glucose levels during gestation. There was a positive correlation between hsp60 and hsp70 levels and the total number of malformations (R∈=∈0.5908, P∈=∈0.0024; R∈=∈0.4877, P∈=∈0.0134, respectively) and the number of malformations per fetus (R∈=∈0.6103, P∈=∈0.0015; R∈=∈0.4875, P∈=∈0.0134, respectively). The anti-hsp60 IgG concentration was correlated with the number of malformations per fetus (R∈=∈0.3887, P∈=∈0.0451) and the anti-hsp70 IgG level correlated with the total number of malformations (R∈=∈0.3999, P∈=∈0.0387). Moreover, both hsp and anti-hsp antibodies showed negative correlations with fetal weight. The results suggest that there is a relationship between hsp60 and hsp70 levels and their respective antibodies and alterations in maternal reproductive performance and impaired fetal development and growth in pregnancies associated with diabetes. © 2012 Cell Stress Society International.

Control of breathing and blood pressure by parafacial neurons in conscious rats

New Findings: • What is the central question of this study? The main purpose of the present manuscript was to investigate the cardiorespiratory responses to hypoxia or hypercapnia in conscious rats submitted to neuronal blockade of the parafacial region. We clearly showed that the integrity of parafacial region is important for the respiratory responses elicited by peripheral and central chemoreflex activation in freely behavior rats. • What is the main finding and its importance? Since the parafacial region is part of the respiratory rhythm generator, they are essential for postnatal survival, which is probably due to their contribution to chemoreception in conscious rats. The retrotrapezoid nucleus (RTN), located in the parafacial region, contains glutamatergic neurons that express the transcriptor factor Phox2b and that are suggested to be central respiratory chemoreceptors. Studies in anaesthetized animals or in vitro have suggested that RTN neurons are important in the control of breathing by influencing respiratory rate, inspiratory amplitude and active expiration. However, the contribution of these neurons to cardiorespiratory control in conscious rats is not clear. Male Holtzman rats (280-300 g, n= 6-8) with bilateral stainless-steel cannulae implanted into the RTN were used. In conscious rats, the microinjection of the ionotropic glutamatergic agonist NMDA (5 pmol in 50 nl) into the RTN increased respiratory frequency (by 42%), tidal volume (by 21%), ventilation (by 68%), peak expiratory flow (by 24%) and mean arterial pressure (MAP, increased by 16 ± 4, versus saline, 3 ± 2 mmHg). Bilateral inhibition of the RTN neurons with the GABAA agonist muscimol (100 pmol in 50 nl) reduced resting ventilation (52 ± 34, versus saline, 250 ± 56 ml min-1 kg-1 with absolute values) and attenuated the respiratory response to hypercapnia and hypoxia. Muscimol injected into the RTN slightly reduced resting MAP (decreased by 13 ± 7, versus saline, increased by 3 ± 2 mmHg), without changing the effects of hypercapnia or hypoxia on MAP and heart rate. The results suggest that RTN neurons activate facilitatory mechanisms important to the control of ventilation in resting, hypoxic or hypercapnic conditions in conscious rats. © 2012 The Authors. Experimental Physiology © 2012 The Physiological Society.

Fractal dimension and Shannon's entropy analyses of the architectural complexity caused by the inflammatory reactions induced by highly crystalline polyvinyl alcohol) microspheres implanted in subcutaneous tissues of the Wistar rats

The results of the histopathological analyses after the implantation of highly crystalline PVA microspheres in subcutaneous tissues of Wistar rats are here in reported. Three different groups of PVA microparticles were systematically studied: highly crystalline, amorphous, and commercial ones. In addition to these experiments, complementary analyses of architectural complexity were performed using fractal dimension (FD), and Shannon's entropy (SE) concepts. The highly crystalline microspheres induced inflammatory reactions similar to the ones observed for the commercial ones, while the inflammatory reactions caused by the amorphous ones were less intense. Statistical analyses of the subcutaneous tissues of Wistar rats implanted with the highly crystalline microspheres resulted in FD and SE values significantly higher than the statistical parameters observed for the amorphous ones. The FD and SE parameters obtained for the subcutaneous tissues of Wistar rats implanted with crystalline and commercial microparticles were statistically similar. Briefly, the results indicated that the new highly crystalline microspheres had biocompatible behavior comparable to the commercial ones. In addition, statistical tools such as FD and SE analyses when combined with histopathological analyses can be useful tools to investigate the architectural complexity tissues caused by complex inflammatory reactions. © 2012 WILEY PERIODICALS, INC.

Photodynamic therapy for the treatment of induced mammary tumor in rats

The objective of this work was to evaluate photodynamic therapy (PDT) by using a hematoporphyrin derivative as a photosensitizer and light-emitting diodes (LEDs) as light source in induced mammary tumors of Sprague-Dawley (SD) rats. Twenty SD rats with mammary tumors induced by DMBA were used. Animals were divided into four groups: control (G1), PDT only (G2), surgical removal of tumor (G3), and submitted to PDT immediately after surgical removal of tumor (G4). Tumors were measured over 6 weeks. Lesions and surgical were LEDs lighted up (200 J/cm2 dose). The light distribution in vivo study used two additional animals without mammary tumors. In the control group, the average growth of tumor diameter was approximately 0.40 cm/week. While for PDT group, a growth of less than 0.15 cm/week was observed, suggesting significant delay in tumor growth. Therefore, only partial irradiation of the tumors occurred with a reduction in development, but without elimination. Animals in G4 had no tumor recurrence during the 12 weeks, after chemical induction, when compared with G3 animals that showed 60 % recurrence rate after 12 weeks of chemical induction. PDT used in the experimental model of mammary tumor as a single therapy was effective in reducing tumor development, so the surgery associated with PDT is a safe and efficient destruction of residual tumor, preventing recurrence of the tumor. © 2012 Springer-Verlag London Ltd.

Experimental development of bisphosphonate-related osteonecrosis of the jaws in rodents

Osteonecrosis of the jaw (ONJ) following the use of bisphosphonates has become of increased interest in the scientific community, due in particular to its as-yet-unsolved pathogenesis. An experimental model of ONJ was induced in normal male rats [alendronate (ALN); 1 mg/Kg/day; n = 10] and matched controls (saline solution; n = 10). After 60 days of drug treatment, all animals were subjected to extractions of the left first lower molars and were euthanized at 3 and 28 days postsurgery. The following analyses were performed: (i) descriptive and quantitative (scores) histological evaluation, (ii) stereometry of distal sockets and (iii) biochemical measurement of C-telopeptide cross-linked collagen type I (CTX) and bone-specific alkaline phosphatase (BALP). The results showed that 28 days postsurgery the animals treated with ALN had areas of exposed and necrotic bone, associated with significant infection, especially in the interalveolar septum area and crestal regions, compared with controls. The levels of CTX, BALP and bone volume, as well as the degrees of inflammation and vascularization, were significantly reduced in these animals. Therefore, analysis of the data presented suggests that ALN therapy is associated with the development of osteonecrosis in the jaws of rodents after tooth extraction. © 2012 International Journal of Experimental Pathology.

Influence of treatment with quercetin on lipid parameters and oxidative stress of pregnant diabetic rats

Among the numerous coadjuvant therapies that could influence the incidence and progression of diabetic complications, antioxidants and flavonoids are currently being tested in clinical trials. We investigated the effect of quercetin on biochemical parameters in streptozotocin-induced (60 mg/kg body mass, by intraperitoneal injection) diabetic rats. A total of 32 female Wistar rats were distributed among 4 groups as follows: control (G1); control treated with quercetin (G2); diabetic (G3); and diabetic treated with quercetin (G4). Quercetin administered to pregnant diabetic rats controlled dyslipidemia and improved lipid profiles in diabetes mellitus, regulated oxidative stress by reducing the generation of lipid hydroperoxides, and increased the activity of the antioxidant enzyme glutathione peroxidase.

Evaluation of effect of cyclosporine A on the bone tissue with induced periodontal disease to ligature in rats

The administration of cyclosporine A (CsA) has been associated with significant bone loss and increased bone remodeling. The present investigation was designed to evaluate the effects of CsA on alveolar bone of rats subjected to experimental periodontitis, using histomorphometric and histological analysis. Twenty-four rats were divided into groups with 6 animals each: 1, control; 2, rats with ligature around the lower first molars; 3, rats with ligature around the lower first molars and that were treated with 10 mg CsA/kg of body weight/d; and 4, rats treated with 10 mg CsA/kg of body weight/d. At the end of 30 days, rats were humanely killed and subjected to a histological processing, with analysis of the distance cemento-enamel junction and alveolar bone crest, bone area, eroded bone area, and cemento surface. All of them were assessed at the mesial region of the alveolar bone. The CsA therapy combined with ligature placement decreased bone area and increased the eroded bone area around the tooth surface. The results at the histological analysis showed the same combination and changes. Therefore, in spite of the lack of a direct effect on the alveolar bone height, the CsA therapy intensified the imbalance of the alveolar bone homeostasia in a rat model of experimental periodontitis. © 2013 Elsevier Inc.

Alterations in the duodenum myenteric neurons of Wistar rats after ingesting of 2,4 dichlorophenoxyacetic acid

The 2,4 dichlorophenoxyacetic acid (2,4-D) is a systemic herbicide whose effects in animal organic systems have been examined in previous studies, being the neurotoxicity considered the predominant effect. However, the studies that detect the 2,4-D neurotoxicity have merely focused in the central nervous system, and therefore, little is known about the effect of this herbicide in the enteric nervous system. This study aimed to verifying the 2,4-D effects on the myenteric neurons in duodenum of Wistar rats. Ten 60-day-old male Wistar rats (Rattus norvegicus) were divided in two groups: control group (C) that did not receive 2,4-D and experimental group (E) that received 5.0 mg of 2,4-D/kg for 15 days. At the end of experimental period, the animal were euthanized, the duodenum was collected and processed for NADPH-diaphorase histochemical analysis in order to expose the nitrergic myenteric neurons (NADPH-dp). In the light microscopy analysis, the whole-mount preparation obtained from duodenum of each animal were image-captured in 120 and 40 fields, for quantitative and morphometric analyses of myenteric neurons, respectively. The neuronal density was not affected when comparing the two groups, but an increase (p > 0.05) of 8.5% was observed in the cell body area of neurons in the E group. In conclusion, the ingestion of 2,4-D at a dosage of 5.0 mg/kg body weight for 15 days does not change the neuronal density, but promotes the hypertrophy of NADPH-dp myenteric neurons in duodenum of the rats of this study.

Slimmer or Fertile? Pharmacological Mechanisms Involved in Reduced Sperm Quality and Fertility in Rats Exposed to the Anorexigen Sibutramine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)