Acute inhibition of estradiol synthesis impacts vestibulo-ocular reflex adaptation and cerebellar long-term potentiation in male rats

The vestibulo-ocular reflex (VOR) adaptation is an ideal model for investigating how the neurosteroid 17 beta-estradiol (E2) contributes to the modification of behavior by regulating synaptic activities. We hypothesized that E2 impacts VOR adaptation by affecting cerebellar synaptic plasticity at the parallel fiber–Purkinje cell (PF) synapse. To verify this hypothesis, we investigated the acute effect of blocking E2 synthesis on gain increases and decreases in adaptation of the VOR in male rats using an oral dose (2.5 mg/kg) of the aromatase inhibitor letrozole. We also assessed the effect of letrozole on synaptic plasticity at the PF synapse in vitro, using cerebellar slices from male rats. We found that letrozole acutely impaired both gain increases and decreases adaptation of the VOR without altering basal ocular-motor performance. Moreover, letrozole prevented long-term potentiation at the PF synapse (PF-LTP) without affecting long-term depression (PF-LTD). Thus, in male rats neurosteroid E2 has a relevant impact on VOR adaptation and affects exclusively PF-LTP. These findings suggest that E2 might regulate changes in VOR adaptation by acting locally on cerebellar and extra-cerebellar synaptic plasticity sites

Sensory inflow manipulation induces learning-like phenomena in motor behavior

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: Perceptual and goal-directed behaviors may be improved by repetitive sensory stimulations without practice-based training. Focal muscle vibration (f-MV) modulating the spatiotemporal properties of proprioceptive inflow is well-suited to investigate the effectiveness of sensory stimulation in influencing motor outcomes. Thus, in this study, we verified whether optimized f-MV stimulation patterns might affect motor control of upper limb movements. Methods: To answer this question, we vibrated the slightly tonically contracted anterior deltoid (AD), posterior deltoid (PD), and pectoralis major muscles in different combinations in forty healthy subjects at a frequency of 100 Hz for 10 min in single or repetitive administrations. We evaluated the vibration effect immediately after f-MV application on upper limb targeted movements tasks, and one week later. We assessed target accuracy, movement mean and peak speed, and normalized Jerk using a 3D optoelectronic motion capture system. Besides, we evaluated AD and PD activity during the tasks using wireless electromyography. Results: We found that f-MV may induce increases (p \u3c 0.05) in movement accuracy, mean speed and smoothness, and changes (p \u3c 0.05) in the electromyographic activity. The main effects of f-MV occurred overtime after repetitive vibration of the AD and PD muscles. Conclusion: Thus, in healthy subjects, optimized f-MV stimulation patterns might over time affect the motor control of the upper limb movement. This finding implies that f-MV may improve the individual’s ability to produce expected motor outcomes and suggests that it may be used to boost motor skills and learning during training and to support functional recovery in rehabilitation

Profilo nutrizionale, composizione corporea e maturazione sessuale degli atleti di ginnastica ritmica adolescenti

A ginástica rí­tmica é um esporte caracterizado pela realização de movimentos que demandam muita flexibilidade e resistência. Alguns critérios são indispensáveis para essa prática esportiva, sendo que o estado nutricional das atletas deve seguir algumas exigências especí­ficas. O objetivo deste trabalho foi analisar o perfil antropométrico, maturação sexual e consumo alimentar de atletas de ginástica rí­tmica. Participaram da pesquisa 12 voluntárias (10 a 13 anos) de um determinado centro de treinamento localizado em uma cidade no interior de SP, onde realizou-se as seguintes avaliações: antropometria (peso e estatura), composição corporal (bioimpedância), consumo alimentar (recordatórios de 24 horas) e maturação sexual (escalas de Tanner). Os resultados encontrados apresentaram que 91,7% das atletas estavam classificadas como eutróficas e um percentual de gordura corporal médio de 21,6 ± 6,8. Quanto a ingestão calórica, as atletas consumiram 33,6 ± 7,3 Kcal/kg, valores abaixo do preconizado pela Sociedade Brasileira de Nutrição Esportiva, sendo que o consumo de macronutrientes constatou uma baixa ingestão de carboidratos (4,7 ± 1,3 g/Kg/dia), uma alta ingestão de proteí­nas (2,7 ± 1,0 g/Kg/dia) e de lipí­dios (1,2 ± 0,3 g/Kg/dia) quando comparado a mesma diretriz. Por outro lado, a maioria das atletas já estavam em estágios maturacionais mais avançados tanto para pelos pubianos como para seios. Conclui-se que apesar da maioria das atletas estarem classificadas como eutróficas e/ou com um percentual de gordura dentro do aceitável, elas apresentaram erros alimentares que podem contribuir para uma queda no desempenho e/ou comprometer o desenvolvimento fí­sico.La gimnasia rítmica es un deporte que se caracteriza por la realización de movimientos que exigen mucha flexibilidad y resistencia. Algunos criterios son esenciales para este deporte, y el estado nutricional de los atletas debe seguir unos requisitos específicos. El objetivo de este trabajo fue analizar el perfil antropométrico, la maduración sexual y el consumo alimentario de atletas de gimnasia rítmica. Doce voluntarios (de 10 a 13 años) participaron de la investigación de un centro de entrenamiento específico ubicado en una ciudad del interior de SP, donde se realizaron las siguientes evaluaciones: antropometría (peso y talla), composición corporal (bioimpedancia), alimentación consumo (recuerdos de 24 horas) y maduración sexual (escalas de Tanner). Los resultados encontrados mostraron que el 91,7% de los atletas fueron clasificados como eutróficos y un porcentaje de grasa corporal promedio de 21,6 ± 6,8. En cuanto a la ingesta calórica, los atletas consumieron 33,6 ± 7,3 Kcal/kg, valores por debajo de lo recomendado por la Sociedad Brasileña de Nutrición Deportiva, y el consumo de macronutrientes mostró una baja ingesta de carbohidratos (4,7 ± 1,3 g/kg/día) , una ingesta elevada de proteínas (2,7 ± 1,0 g/kg/día) y lípidos (1,2 ± 0,3 g/kg/día) en comparación con la misma pauta. Por otro lado, la mayoría de las atletas ya se encontraban en etapas de maduración más avanzadas tanto para el vello púbico como para los senos. Se concluye que a pesar de que la mayoría de los deportistas se clasifican como eutróficos y/o con un porcentaje de grasa aceptable, presentan errores dietéticos que pueden contribuir a la caída del rendimiento y/o comprometer el desarrollo físico.Rhythmic gymnastics is a sport characterized by movements that demand a lot of flexibility and endurance. Some criteria are indispensable for this sport practice, and the nutritional status of the athletes must follow some specific requirements. The objective of this study was to analyze the anthropometric profile, sexual maturation and dietary intake of athletes of rhythmic gymnastics. Participants were 12 volunteers (10 to 13 years old) from a specific training center located in a city in the interior of SP, where the following evaluations were carried out: anthropometry (weight and height), body composition (bioimpedance), food consumption (24-hour recall) and sexual maturation (Tanner scales). The results showed that 91.7% of the athletes were classified as eutrophic and a mean body fat percentage of 21.6 ± 6.8. As for caloric intake, the athletes consumed 33.6 ± 7.3 Kcal / kg, values lower than that recommended by the Brazilian Society of Nutrition, and macronutrient consumption found a low carbohydrate intake (4.7 ± 1.3 g / kg / day), a high protein intake (2.7 ± 1.0 g / kg / day) and lipids (1.2 ± 0.3 g / kg / day) when compared to the same guideline. On the other hand, most athletes were already in advanced maturational stages for both pubic hair and breasts. It is concluded that although most athletes are classified as eutrophic and / or with a percentage of fat within acceptable, they presented eating errors that may contribute to a drop in performance and / or compromise physical development.A ginástica rí­tmica é um esporte caracterizado pela realização de movimentos que demandam muita flexibilidade e resistência. Alguns critérios são indispensáveis para essa prática esportiva, sendo que o estado nutricional das atletas deve seguir algumas exigências especí­ficas. O objetivo deste trabalho foi analisar o perfil antropométrico, maturação sexual e consumo alimentar de atletas de ginástica rí­tmica. Participaram da pesquisa 12 voluntárias (10 a 13 anos) de um determinado centro de treinamento localizado em uma cidade no interior de SP, onde realizou-se as seguintes avaliações: antropometria (peso e estatura), composição corporal (bioimpedância), consumo alimentar (recordatórios de 24 horas) e maturação sexual (escalas de Tanner). Os resultados encontrados apresentaram que 91,7% das atletas estavam classificadas como eutróficas e um percentual de gordura corporal médio de 21,6 ± 6,8. Quanto a ingestão calórica, as atletas consumiram 33,6 ± 7,3 Kcal/kg, valores abaixo do preconizado pela Sociedade Brasileira de Nutrição Esportiva, sendo que o consumo de macronutrientes constatou uma baixa ingestão de carboidratos (4,7 ± 1,3 g/Kg/dia), uma alta ingestão de proteí­nas (2,7 ± 1,0 g/Kg/dia) e de lipí­dios (1,2 ± 0,3 g/Kg/dia) quando comparado a mesma diretriz. Por outro lado, a maioria das atletas já estavam em estágios maturacionais mais avançados tanto para pelos pubianos como para seios. Conclui-se que apesar da maioria das atletas estarem classificadas como eutróficas e/ou com um percentual de gordura dentro do aceitável, elas apresentaram erros alimentares que podem contribuir para uma queda no desempenho e/ou comprometer o desenvolvimento fí­sico.La ginnastica ritmica è uno sport caratterizzato dall'esecuzione di movimenti che richiedono molta flessibilità e resistenza. Alcuni criteri sono essenziali per questo sport e lo stato nutrizionale degli atleti deve seguire alcuni requisiti specifici. L'obiettivo di questo lavoro è stato quello di analizzare il profilo antropometrico, la maturazione sessuale e il consumo alimentare degli atleti di ginnastica ritmica. Dodici volontari (dai 10 ai 13 anni) hanno partecipato alla ricerca da uno specifico centro di formazione situato in una città all'interno di SP, dove sono state effettuate le seguenti valutazioni: antropometria (peso e altezza), composizione corporea (bioimpedenza), alimentazione consumo (richiami di 24 ore) e maturazione sessuale (scale Tanner). I risultati trovati hanno mostrato che il 91,7% degli atleti era classificato come eutrofico e una percentuale media di grasso corporeo di 21,6 ± 6,8. Per quanto riguarda l'apporto calorico, gli atleti hanno consumato 33,6 ± 7,3 Kcal/kg, valori inferiori a quelli consigliati dalla Società Brasiliana di Nutrizione Sportiva, e il consumo di macronutrienti ha mostrato un basso apporto di carboidrati (4,7 ± 1,3 g/kg/giorno) , un elevato apporto di proteine ​​(2,7 ± 1,0 g/kg/giorno) e lipidi (1,2 ± 0,3 g/kg/giorno) rispetto alla stessa linea guida. D'altra parte, la maggior parte degli atleti era già in stadi di maturazione più avanzati sia per i peli pubici che per il seno. Si conclude che nonostante la maggior parte degli atleti sia stata classificata come eutrofica e/o con una percentuale di grasso accettabile, ha avuto errori dietetici che possono contribuire a un calo delle prestazioni e/o compromettere lo sviluppo fisico

Joint torques and tibiofemoral joint reaction force in the bodyweight "wall squat" therapeutic exercise

This study provides a biomechanical analysis of the bodyweight wall-squat exercise considering four exercise variants: knee angle; horizontal hip-ankle distance (d); shift between the rearfoot and forefoot of the centre of pressure (xGR) of the ground reaction force; back supported via the scapular or pelvic zone. The ankle and hip angles corresponding to a given knee angle can be modulated, changing the distance d, to manage limitation in lumbopelvic and ankle mobility. The knee-extensor muscles can be overloaded (250 Nm muscle torque) with knees flexed at 90°, back supported through the pelvic zone, and feet away from the wall (d = 50 cm). Scapular support, xGR at forefoot, and d = 50 cm, yield a higher level of muscle-torque for hip-extension (130 Nm) and knee-flexion (65 Nm), with knees at 90° of flexion or near full extension, respectively. Ankle-dorsiflexion (plantarflexion) muscle torque up to 40 Nm is reached with xGR at the forefoot (rearfoot). This study may aid trainers and therapists to finely modulate the muscle torques (up to the above-mentioned levels) by an appropriate selection of exercise variants for training or rehabilitation purposes. Low levels (60 N) of anterior tibial pull may occur near 25° of knee flexion with xGR at the rearfoot

De novo synthesized estradiol: a role in modulating the cerebellar function

The estrogen estradiol is a potent neuroactive steroid that may regulate brain structure and function. Although the effects of estradiol have been historically associated with gonadal secretion, the discovery that this steroid may be synthesized within the brain has expanded this traditional concept. Indeed, it is accepted that de novo synthesized estradiol in the nervous system (nE2) may modulate several aspects of neuronal physiology, including synaptic transmission and plasticity, thereby influencing a variety of behaviors. These modulations may be on a time scale of minutes via non-classical and often membrane-initiated mechanisms or hours and days by classical actions on gene transcription. Besides the high level, recent investigations in the cerebellum indicate that even a low aromatase expression can be related to the fast nE2 effect on brain functioning. These pieces of evidence point to the importance of an on-demand and localized nE2 synthesis to rapidly contribute to regulating the synaptic transmission. This review is geared at exploring a new scenario for the impact of estradiol on brain processes as it emerges from the nE2 action on cerebellar neurotransmission and cerebellum-dependent learning

Dynamic functions of GABA signaling during granule cell maturation

The dentate gyrus is one of the few areas of the brain where new neurons are generated throughout life. Neural activity influences multiple stages of neurogenesis, thereby allowing experience to regulate the production of new neurons. It is now well established that GABAA receptor-mediated signaling plays a pivotal role in mediating activity-dependent regulation of adult neurogenesis. GABA first acts as a trophic signal that depolarizes progenitors and early post mitotic granule cells, enabling network activity to control molecular cascades essential for proliferation, survival and growth. Following the development of glutamatergic synaptic inputs, GABA signaling switches from excitatory to inhibitory. Thereafter robust synaptic inhibition enforces low spiking probability of granule cells in response to cortical excitatory inputs and maintains the sparse activity patterns characteristic of this brain region. Here we review these dynamic functions of GABA across granule cell maturation, focusing on the potential role of specific interneuron circuits at progressive developmental stages. We further highlight questions that remain unanswered about GABA signaling in granule cell development and excitability

A atuação feminina nos Conselhos da Mulher: um estudo dos Conselhos de Pelotas e de Santa Cruz do Sul/RS

O artigo tem como proposta refletir sobre a atuação feminina em Conselhos Municipais da Mulher. A primeira parte apresenta uma concisa revisão da literatura que discute a legitimidade da representação dos atores presentes nos fóruns de deliberação de políticas públicas no Brasil; a segunda parte inicia com breve apresentação da pesquisa que investigou os Conselhos da Mulher de dois municípios do estado do Rio Grande do Sul, seguida dos dados resultantes do questionário aplicado às conselheiras; por fim, algumas considerações são apresentadas visando configurar o perfil das conselheiras e de pensar os dados à luz da discussão sobre legitimidade da representação

Electromyographic and Stabilometric Analysis of the Static and Dynamic “Standing Bird Dog” Exercise

(1) Background: The “bird dog” exercise is considered one of the most effective therapeutic exercises for lumbopelvic rehabilitation and the prevention and treatment of low back pain. The “standing bird dog” (SBD) exercise, executed in a single-leg stance, constitutes a natural and challenging variation in the “bird dog”; nevertheless, this exercise has not yet been investigated. This study provides a stabilometric and electromyographic analysis of the SBD performed in static and dynamic conditions and in ipsilateral and contralateral variations; (2) Methods: A time-synchronized motion capture system, wireless electromyography sensors, and triaxial force platform were used to analyze the selected SBD exercises; (3) Results: In dynamic conditions, the gluteus maximum, multifidus, lumbar erector spinae, and gluteus medius reached a mean activation level higher than in the static condition, with peak activation levels of 80%, 60%, 55%, and a 45% maximum voluntary isometric contraction, respectively. In the static condition, balance control was more challenging in the mediolateral compared to the anteroposterior direction. In the dynamic condition, the balance challenge was higher in the anteroposterior direction and higher than the static condition in both directions; (4) Conclusions: The SBD was proved to be effective for strengthening the hip and lumbar extensor muscles and provided a powerful challenge to single-leg balance control in both mediolateral and anteroposterior directions

Bilateral Activity of Spine Extensors and Rotators during Asymmetric Lumbar Stabilization Exercises Executed in Prone, Quadruped, and Standing-Prone Positions

(1) Background: Most daily activities and sport gestures involve asymmetric movement patterns of the upper and lower extremities, transferring asymmetric mechanical loadings to the spine. Therefore, asymmetric lumbar stabilization exercises are frequently prescribed in athletic programs and preventive/rehabilitation interventions. This study analyzed the bilateral activity of the thoracic erector spinae (ES), lumbar multifidus (MF), external oblique (EO), and internal oblique (IO) during asymmetric lumbar stabilization exercises executed in prone, quadruped, and standing-prone positions, rising an upper and/or lower limb in all possible combinations. A limited subset of these data has been previously published in earlier studies. (2) Methods: Surface EMG signals were bilaterally recorded from the selected muscles using wireless EMG sensors. (3) Results: ES, MF, and oblique muscles’ activity was significantly higher in prone, standing-prone, and quadruped positions, respectively, and was maximized by specific limb rise combinations (up to 69%, 64%, 34%, and 24% maximum-voluntary-isometric-contraction for ES, MF, EO, and IO). The bilateral difference in muscle activation was significantly higher in the quadruped position and revealed different strategies used to stabilize the body in response to the different exercise conditions. (4) Conclusions: The study results can provide deeper insights into the stabilizing function of the lumbar and oblique muscles and aid in designing optimal progressions for lumbar stabilization exercises