Effects of early movement restriction on sensorimotor development and motor performance in rat

International audienc

Effects of early movement restriction on sensorimotor development and motor performance in rat

International audienceChildhood is a period of construction of the organism, during which regular physical activity favors the maturation of the neuronal networks. However, some children are hypoactive because they are bedridden (illness, accident, cerebral palsy...) or they suffer from a developmental coordination disorder. In addition to the increased risk of cardiovascular and metabolic diseases, a low level of physical activity during childhood can affect the structuring and maturation of muscle and of developing neuronal network, that may lead to cognitive and behavioral impairment. In order to better understand the emergence of neuromuscular disorders in these children, a model of sensorimotor restriction (SMR) was developed in rats. It consists in casting hindlimbs of the pups from postnatal day (PND) 1 to PND 28. These animals display a prominent motor phenotype that includes muscle weakness, locomotor disturbances and spinal hyperreflexia.In the present study, our objective was first to characterize the effect of early SMR on sensorimotor development from PND 1 to PND 28. Our results revealed that SMR induced a delay in acquisition of the main neurodevelopmental parameters such as righting, negative geotaxis, cliff avoidance, posture, whereas ocular reflex and limb grasping remained similar to control rats. Moreover, morphological parameters were affected by SMR condition since we observed lower body weight and atrophy of postural muscle. The second objective was to examine whether, after the 28-day SMR period, a one-month recovery period without restriction could restore the sensorimotor performance.The spontaneous activity (running wheels) was progressively increased from PND 35 to PND 60, but sensorimotor tests that require a good coordination between intra- and interlimb (rotarod, locomotion) showed an enduring alteration until PND 60. In conclusion, physical activity and interactions with environment seem necessary for the harmonious maturation of organization and functions of the central nervous system

An innovative program of adapted physical activity coupled with nutrition offered both face-to-face and in distance learning: what are the health benefits for people over 50 with vulnerability criteria ?

International audienc

Early movement restriction affects the acquisition of neurodevelopmental reflexes in rat pups.

International audienceChildhood is a period of construction of the organism, during which interactions with the environment and regular physical activity are necessary for the maturation of the neuronal networks. An atypical sensorimotor activity during childhood (due to bed-rest or neurodevelopmental disorders) impacts the development of the neuromuscular system. A model of sensorimotor restriction (SMR) developed in rats has shown that casting pups' hind limbs from postnatal day 1 (P1) to P28 induced a severe perturbation of motor behavior, due to muscle weakness as well as disturbances within the central nervous system. In the present study, our objective was to determine whether SMR affects the early postnatal ontogenesis. We explored the neuromuscular development through the determination of the age for achievement of the main neurodevelopmental reflexes, which represent reliable indicators of neurological and behavioral development. We also evaluated the maturation of postural control. Our results demonstrate that SMR induces a delay in the motor development, illustrated by a several days delay in the acquisition of a mature posture and in the acquisition reflexes: hind limb grasping, righting, hind limb placing, cliff avoidance, negative geotaxis. In conclusion, impaired physical activity and low interactions with environment during early development result in altered maturation of the nervous system

Effects of early movement restriction on hindlimb muscle irisin levels in rat

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Early movement restriction deteriorates motor function and soleus muscle physiology

International audienceChildren with low physical activity and interactions with environment experience atypical sensorimotor development and maturation leading to anatomical and functional disorganization of the sensorimotor circuitry and also to enduring altered motor function. Previous data have shown that postnatal movement restriction in rats results in locomotor disturbances, functional disorganization and hyperexcitability of the hind limb representations in the somatosensory and motor cortices, without apparent brain damage. Due to the reciprocal interplay between the nervous system and muscle, it is difficult to determine whether muscle alteration is the cause or the result of the altered sensorimotor behavior (Canu et al., 2019). In the present paper, our objectives were to evaluate the impact of early movement restriction leading to sensorimotor restriction (SMR) during development on the postural soleus muscle and on sensorimotor performance in rats, and to determine whether changes were reversed when typical activity was resumed. Rats were submitted to SMR by hind limb immobilization for 16 h / day from birth to postnatal day 28 (PND28). In situ isometric contractile properties of soleus muscle, fiber cross sectional area (CSA) and myosin heavy chain content (MHC) were studied at PND28 and PND60. In addition, the motor function was evaluated weekly from PND28 to PND60. At PND28, SMR rats presented a severe atrophy of soleus muscle, a decrease in CSA and a force loss. The muscle maturation appeared delayed, with persistence of neonatal forms of MHC. Changes in kinetic properties were moderate or absent. The Hoffmann reflex provided evidence for spinal hyperreflexia and signs of spasticity. Most changes were reversed at PND60, except muscle atrophy. Functional motor tests that require a good limb coordination, i.e. rotarod and locomotion, showed an enduring alteration related to SMR, even after one month of 'typical' activity. On the other hand, paw withdrawal test and grip test were poorly affected by SMR whereas spontaneous locomotor activity increased over time. Our results support the idea that proprioceptive feedback is at least as important as the amount of motor activity to promote a typical development of motor function. A better knowledge of the interplay between hypoactivity, muscle properties and central motor commands may offer therapeutic perspectives for children suffering from neurodevelopmental disorders

Impact of 4-month training on glycaemic excursions in daily life in adults living with type 1 diabetes

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Continuous moderate and intermittent high-intensity exercise in youth with type 1 diabetes: Which protection for dysglycemia?

International audienceFrom an early age, exercise is key to managing type 1 diabetes (T1D). However, hypoglycemia around aerobic exercise is a major barrier to physical activity in children. We explore whether intermittent high-intensity aerobic exercise (IHE), designed to mimic spontaneous childhood physical activity patterns, offers better protection against glycemic drop than continuous moderate-intensity exercise (CME). Five boys and 7 girls with T1D (9.8 ± 1.4y) performed ergo cycle-based randomized CME and IHE of identical duration and total mechanical load [50 %PWCvs. 15sec(150 %PWC)/30 sec passive recovery; both during two 10-min sets, 5 min in-between]. Capillary glycemia during exercise and interstitial glucose during recovery were compared between exercises and an inactive condition, controlling for baseline glycemia, carbohydrate and insulin. The exercise-induced decrease in capillary glycemia was attenuated by 1.47 mmol·L for IHE vs. CME (P  16.7 mmol·L compared with inactive days (P < 0.05; CME: 0 %; IHE: 16,7 %; INACTIVE: 41,7 %). IHE appeared to limit the glycemic drop compared to CME. Performing 20-min CME or IHE was not associated with increased hypoglycemic risk compared to being inactive. CME appeared even transiently protective against serious hyperglycemia

Vasoréactivité à l’exercice chez des hommes DT1 suite à une prise unique de cacao : quel impact réel des flavanols?

International audienceContexte– Les personnes vivant avec le diabète de type 1 (DT1) présentent une dysfonction endothéliale précoce, marquée par une diminution de la biodisponibilité en monoxyde d'azote (NO•) et repérable dans des situations de la vie quotidienne telles que l’exercice physique(1). Il apparaît fondamental de trouver et de tester des manipulations non-pharmacologiques pour la prévenir. Parmi les composants bioactifs des aliments, les flavanols du cacao gagnent actuellement l'attention: ils pourraient notamment augmenter la formation du NO• ou empêcher son inactivation. Méthodes– Chez douze hommes DT1 indemnes de complications vasculaires, appariés avec douze hommes non diabétiques, nous avons exploré l’effet d’une prise aigue (+2h) d’un extrait de fèves de cacao, riche en flavanols (900mg) (vs. placebos) sur la réactivité vasculaire au repos (iontophorèse couplée au laser Speckle, FMD) et au cours de l’exercice (NIRS) ainsi que sur des paramètres sanguins relatifs au métabolisme du NO• et au stress oxydant (étude randomisée, contrôlée, en double aveugle). Résultats – Les flavanols ne semblent pas avoir d’effet sur les paramètres sanguins au repos. Au cours de l’exercice, en comparaison du placebo contenant uniquement de la maltodextrine, le placebo contenant de la théobromine et de la caféine (en quantités égales à celles de la condition ‘flavanols’) ainsi que la condition ‘Flavanols’ semblent améliorer la vasoréactivité cérébrale tout en augmentant l’acide urique plasmatique (antioxydant) mais également, de façon surprenante, en augmentant l’endocan (marqueur d’une dysfonction endothéliale). L’effet des flavanols ne différait pas entre les participants DT1 et non diabétiques. Conclusion – Il semblerait que les composés vasoactifs contenus dans l’extrait riche en flavanols issu du cacao soient la théobromine et la caféine plutôt que les flavanols eux-mêmes. Ceci reste à confirmer avec les résultats sur l’exploration vasculaire au repos avant et après ingestion des gélules et sur des paramètres sanguins complémentaires (nitrites…) qui sont en cours d’analyse