Ana Paula Tanno

Determination of the estrous cycle phases of rats: some helpful considerations

The short length of the estrous cycle of rats makes them ideal for investigation of changes occurring during the reproductive cycle. The estrous cycle lasts four days and is characterized as: proestrus, estrus, metestrus and diestrus, which may be determined according to the cell types observed in the vaginal smear. Since the collection of vaginal secretion and the use of stained material generally takes some time, the aim of the present work was to provide researchers with some helpful considerations about the determination of the rat estrous cycle phases in a fast and practical way. Vaginal secretion of thirty female rats was collected every morning during a month and unstained native material was observed using the microscope without the aid of the condenser lens. Using the 10 x objective lens, it was easier to analyze the proportion among the three cellular types, which are present in the vaginal smear. Using the 40 x objective lens, it is easier to recognize each one of these cellular types. The collection of vaginal lavage from the animals, the observation of the material, in the microscope, and the determination of the estrous cycle phase of all the thirty female rats took 15-20 minutes.

Atrial supersensitivity to noradrenaline in stressed female rats

Stress can change the responses to catecholamines in many tissues. The aim of this study was to investigate the influence of the estrous cycle on the sensitivity of right atria to noradrenaline in female rats subjected to acute swimming stress. Female Wistar rats in proestrus, estrus, metestrus or diestrus were submitted to a 50 min-swimming session. Immediately after the exercise, the rats were killed and their right atria were mounted for isometric recording of the spontaneous beating rate. Concentration-effect curves to noradrenaline were obtained before and after the inhibition of neuronal uptake with phenoxybenzamine (10 microM) and of extraneuronal uptake with estradiol (5 microM). Acute swimming stress did not change the right atrial sensitivity to noradrenaline in rats in estrus, metestrus and diestrus. However, swimming stress produced supersensitivity to noradrenaline in proestrus (pD(2) control: 7.14 +/- 0.03 vs. pD(2) swimming: 7.55 +/- 0.04; p<0.05). This supersensitivity was still observed after uptake inhibition. When catecholamine uptake was inhibited, the concentration-effect curve to noradrenaline was shifted to the left 2.5-fold in the proestrus control group and 1.7-fold in the proestrus stress group (p<0.05). In conclusion, the estrous cycle influenced the acute stress-induced atrial supersensitivity to noradrenaline.

Nandrolone and resistance training induce heart remodeling Role of fetal genes and implications for cardiac pathophysiology

AIMS This study was conducted to assess the isolated and combined effects of nandrolone and resistance training on cardiac morphology, function, and mRNA expression of pathological cardiac hypertrophy markers. MAIN METHODS Wistar rats were randomly divided into four groups and submitted to 6 weeks of treatment with nandrolone and/or resistance training. Cardiac parameters were determined by echocardiography. Heart was analyzed for collagen infiltration. Real-time RT-PCR was used to assess the pathological cardiac hypertrophy markers. KEY FINDINGS Both resistance training and nandrolone induced cardiac hypertrophy. Nandrolone increased the cardiac collagen content, and reduced the cardiac index in non-trained and trained groups, when compared with the respective vehicle-treated groups. Nandrolone reduced the ratio of maximum early to late transmitral flow velocity in non-trained and trained groups, when compared with the respective vehicle-treated groups. Nandrolone reduced the alpha-myosin heavy chain gene expression in both non-trained and trained groups, when compared with the respective vehicle-treated groups. Training reduced the beta-myosin heavy chain gene expression in the groups treated with vehicle and nandrolone. Only the association between training and nandrolone increased the expression of the skeletal alpha-actin gene and atrial natriuretic peptide in the left ventricle. SIGNIFICANCE This study indicated that nandrolone, whether associated with resistance training or not, induces cardiac hypertrophy, which is associated with enhanced collagen content, re-expression of fetal genes the in left ventricle, and impaired diastolic and systolic function.

Effects of nandrolone and resistance training on the blood pressure, cardiac electrophysiology, and expression of atrial β-adrenergic receptors

AIMS This study was performed to assess isolated and combined effects of nandrolone and resistance training on the blood pressure, cardiac electrophysiology, and expression of the β1- and β2-adrenergic receptors in the heart of rats. MAIN METHODS Wistar rats were randomly divided into four groups and submitted to a 6-week treatment with nandrolone and/or resistance training. Cardiac hypertrophy was accessed by the ratio of heart weight to the final body weight. Blood pressure was determined by a computerized tail-cuff system. Electrocardiography analyses were performed. Western blotting was used to access the protein levels of the β1- and β2-adrenergic receptors in the right atrium and left ventricle. KEY FINDINGS Both resistance training and nandrolone induced cardiac hypertrophy. Nandrolone increased systolic blood pressure depending on the treatment time. Resistance training decreased systolic, diastolic and mean arterial blood pressure, as well as induced resting bradycardia. Nandrolone prolonged the QTc interval for both trained and non-trained groups when they were compared to their respective vehicle-treated one. Nandrolone increased the expression of β1- and β2-adrenergic receptors in the right atrium for both trained and non-trained groups when they were compared to their respective vehicle-treated one. SIGNIFICANCE This study indicated that nandrolone, associated or not with resistance training increases blood pressure depending on the treatment time, induces prolongation of the QTc interval, and increases the expression of β1- and β2-adrenergic receptors in the cardiac right atrium, but not in the left ventricle.

A administração de nandrolona não promove hipertrofia do músculo sóleo em ratos

Anabolic androgenic steroids (AAS) are compounds formed from testosterone or one of its derivatives, which are largely used by amateur e professional athletes to improve the athletic performance. However, the scientific information about the relation between the use of AAS and muscle hypertrophy is controversial. The aim of this study was to evaluate the effects of testosterone and physical training on muscle hypertrophy. Male Wistar rats received i.m. injections of Deca-Durabolin® or vehicle during 6 weeks. Trained rats were submitted to a resistance physical training, by jumping up and down in water carrying an overload. Sedentary and trained animals were anesthetized and sacrificed. Soleus muscle was removed for the quantification of total protein and DNA concentration. In the end of the treatment, body weight of trained animals treated with vehicle or AAS was lower than the body weight of respective sedentary. Total protein concentration and the ratio muscle weight/body weight of all experimental groups were not altered. Trained group treated with AAS presented lower DNA concentration than trained group treated with vehicle. The administration of nandrolone decanoate did not promote hypertrophy on soleus muscle, not even when the use of AAS was associated to resistance physical training.

Relação entre a administração de esteróide anabólico androgênico, treinamento físico aeróbio e supercompensação do glicogênio

La supercompensacion de glucogeno es una de las adaptaciones inducidas por el entrenamiento fisico. Visualizando potencializar este fenomeno, muchos atletas utilizan dosis suprafisiologicas de estos esteroides anabolicos androgenicos (EAA). El objetivo de este estudio fue el de evaluar en ratas los efectos de nandrolona y del ejercicio aerobico sobre el peso corporal, los trigliceridos, la gluclosa y las reservas de glucogeno. Ratas Wistar machos fueron aleatoriamente divididas en 4 grupos: sedentarios + vehiculo (SV), entrenada + vehiculo (EV), sedentario + EAA (SEAA) y entrenada + EAA (EEAA, n = 7-14/grupo). Recibieron una inyeccion intramuscular de nandrolona en vehiculo durante dos semanas y durante este mismo periodo los animales entrenados fueron sometidos a ejercicio aerobico. Los datos fueron analizados usando las pruebas estadisticas ANOVA bifactorial y Tukey (p (SV: 0,2 ± 0,02 = SEAA: 0,21 ± 0,02mg/100mg)]. La glucemia y las reservas de glucogeno del soleo permanecieron inalteradas. El uso de dosis superfisiologicas de nandrona no potencializaron ninguno de los efectos obtenidos en respuesta al entrenamiento aerobico.Glycogen supercompensation is one of the adaptations induced by physical training. To potentiate this phenomenon, many athletes use supraphysiological doses of anabolic androgenic steroids (AAS). The purpose of this study was to evaluate the effects of nandrolo- ne and aerobic physical exercise in rats, on body weight, plasmatic triglycerides levels, blood glucose and glycogen content. Male Wistar rats were randomly divided into 4 groups: Sedentary + ve- hicle (SV), Trained + vehicle (TV), Sedentary + AAS (SAAS) and Trained + AAS (TAAS) (n = 7-14/group). They received i.m. injec- tions of nandrolone or vehicle for 9 weeks, and during the same period trained rats were submitted to aerobic exercise. Data were analyzed by two-way ANOVA and Tukey tests (p (SV: 0,2 ± 0,02 = SAAS: 0,21 ± 0,02 mg/100 mg)). Blood glucose and soleus glycogen reserves re- mained unaltered. The use of supraphysiological doses of nandrolo- ne did not potentiate any of the effects obtained in response to aerobic physical training.

Dyslipidemia Induced by Stress

The pioneering work of Hans Selye (1936) led to the use of the word “stress” in a biological context gaining popularity world-wide. Stress is as an organic response to stressors that can be aversive stimuli or unknown situations capable of compromising homeostasis. During the stress reaction, the sympathetic nervous system and hypothalamic–pituitary–adrenal axis are stimulated. Consequently, serum concentrations of classical stress hormones, namely catecholamines and glucocorticoids, are increased and act on cells and tissues inducing adaptive changes in order to protect the organism and allow its survival. In addition, the stress reaction can also modulate immune system activities and the secretion of other hormones (gonadotrophins, estrogen, testosterone, thyroid, angiotensins). Considering that organic homeostatic systems are subject to frequent environmental and internal variations, Sterling and Eyer (1988) proposed the term alostasis to describe the adaptative processes that actively maintain stability through physiological changes. The terms eustress and efficient allostasis describe facile adaptation, such as a quick peak stress response to mobilize energy to deal with an acute stressor, and a rapid return to baseline, when the stressor terminates. On the other hand, distress or allostatic load refers to an imbalance in systems that promote adaptation (Epel, 2009; Korte et al., 2005). This imbalance can simply be the result of too much repeated stress, but it can also be the result of adaptative systems that are out of balance and fail to shut-off or, alternatively, systems that fail to return to normal (Epel, 2009). Therefore the shut-off of the stress response is particularly important, because, when systems do not shut off in time, they can cause damage or promote pathology (McEwen, 1998). The classical stress hormones, glucocorticoids (cortisol) and catecholamines (epinephrine and norepinephrine), are catabolic and modulate the breakdown of glycogen, triglycerides and proteins into molecules that can be rapidly metabolized in order to generate energy (Black, 2002). These responses enable energy substrates to be directed to organs and tissues

Estresse, ciclo reprodutivo e sensibilidade cardíaca às catecolaminas

Stress is an organic answer to aversive stimulus or unknown situations to provide the adaptation of host to the new condition. The stressor can be a physical, chemical, emotional and social agent. Different stressors are present in human daily life and can be involved in degenerative diseases and lead to a fast aging process disturbing the body physiology. The main mediators of the stress reaction are the catecholamines (norepinephrine and epinephrine) released by the sympathetic nervous system and by the adrenal medulla, and the glucocorticoids released by the adrenal cortex. The catecholamines and glucocorticoids act in the cells and tissues inducing adaptive changes in order to protect the organism and allow its survival. This response to stressors can be modified by the host and stressor characteristics. Among the host ones, age, gender, and in females, the reproductive cycle are relevant. The variations in the levels of sexual steroids estradiol and progesterone, related to the reproductive cycle, modulate the secretion of CRH, ACTH and glucocorticoids during the stress reaction and are involved in the different responses between men and women. Many studies have shown that the exposure to stressors may induce alterations in the sensitivity to catecholamines in the heart, which are related to adaptive processes. These alterations include changes in the activity of the metabolizing system of catecholamines, in the affinity or number of adrenoceptors, in the coupling between the receptor and G protein, and in enzymes mediating intracellular processes after the receptor activation. The study of these alterations may be helpful to the understanding of the cardiac effects of the water activities and swimming in humans.

Analise do significado do tempo de imobilidade em modelos experimentais de natacao

The aim of this work was to evaluate if the meaning of immobility (helplessness or adaptation) depends on the experimental model (forced swimming test or swimming stress). Immobility time (IT) and glycogen mobilization of rats submitted to swimming session were analyzed in two protocols: swimming stress (SS) and forced swimming test (FST). We also compared the effects of desipramine and diazepam. The experiments were recorded to evaluate the IT. The rats, after swimming session, were sacrificed and hepatic and muscles samples were prepared to the quantification of glycogen. IT was lower in SS than in FST (p=0.001). Hepatic glycogen concentration were different one from another (control>FST>SS;p<0.05). The glycogen concentrations at gastrocnemius and soleus muscles were lower at SS compared to FST and control (p<0.05). The IT was recorded and measured from another group treated with desipramine and diazepam. Desipramine decreased the IT in the FST but not in the SS. Diazepam increased the IT in the SS but not in the FST. We conclude that SS and FST induced different physiological and behavioral responses and represent different situations for the animal.

Relation between anabolic androgenic steroid administration, aerobic physical training and glycogen supercompensation

La supercompensacion de glucogeno es una de las adaptaciones inducidas por el entrenamiento fisico. Visualizando potencializar este fenomeno, muchos atletas utilizan dosis suprafisiologicas de estos esteroides anabolicos androgenicos (EAA). El objetivo de este estudio fue el de evaluar en ratas los efectos de nandrolona y del ejercicio aerobico sobre el peso corporal, los trigliceridos, la gluclosa y las reservas de glucogeno. Ratas Wistar machos fueron aleatoriamente divididas en 4 grupos: sedentarios + vehiculo (SV), entrenada + vehiculo (EV), sedentario + EAA (SEAA) y entrenada + EAA (EEAA, n = 7-14/grupo). Recibieron una inyeccion intramuscular de nandrolona en vehiculo durante dos semanas y durante este mismo periodo los animales entrenados fueron sometidos a ejercicio aerobico. Los datos fueron analizados usando las pruebas estadisticas ANOVA bifactorial y Tukey (p (SV: 0,2 ± 0,02 = SEAA: 0,21 ± 0,02mg/100mg)]. La glucemia y las reservas de glucogeno del soleo permanecieron inalteradas. El uso de dosis superfisiologicas de nandrona no potencializaron ninguno de los efectos obtenidos en respuesta al entrenamiento aerobico.Glycogen supercompensation is one of the adaptations induced by physical training. To potentiate this phenomenon, many athletes use supraphysiological doses of anabolic androgenic steroids (AAS). The purpose of this study was to evaluate the effects of nandrolo- ne and aerobic physical exercise in rats, on body weight, plasmatic triglycerides levels, blood glucose and glycogen content. Male Wistar rats were randomly divided into 4 groups: Sedentary + ve- hicle (SV), Trained + vehicle (TV), Sedentary + AAS (SAAS) and Trained + AAS (TAAS) (n = 7-14/group). They received i.m. injec- tions of nandrolone or vehicle for 9 weeks, and during the same period trained rats were submitted to aerobic exercise. Data were analyzed by two-way ANOVA and Tukey tests (p (SV: 0,2 ± 0,02 = SAAS: 0,21 ± 0,02 mg/100 mg)). Blood glucose and soleus glycogen reserves re- mained unaltered. The use of supraphysiological doses of nandrolo- ne did not potentiate any of the effects obtained in response to aerobic physical training.