Morici G

Mild Aerobic Exercise Training Hardly Affects the Diaphragm of mdx Mice

In the mdx mice model of Duchenne Muscular Dystrophy (DMD), mild endurance exercise training positively affected limb skeletal muscles, whereas few and controversial data exist on the effects of training on the diaphragm. The diaphragm was examined in mdx (C57BL/10ScSn‐Dmdmdx) and wild‐type (WT, C57BL/10ScSc) mice under sedentary conditions (mdx‐SD, WT‐SD) and during mild exercise training (mdx‐EX, WT‐EX). At baseline, and after 30 and 45 days (training: 5u2009d/wk for 6 weeks), diaphragm muscle morphology and Cx39 protein were assessed. In addition, tissue levels of the chaperonins Hsp60 and Hsp70 and the p65 subunit of nuclear factor‐kB (NF‐kB) were measured in diaphragm, gastrocnemius, and quadriceps in each experimental group at all time points. Although morphological analysis showed unchanged total area of necrosis/regeneration in the diaphragm after training, there was a trend for larger areas of regeneration than necrosis in the diaphragm of mdx‐EX compared to mdx‐SD mice. However, the levels of Cx39, a protein associated with active regeneration in damaged muscle, were similar in the diaphragm of mdx‐EX and mdx‐SD mice. Hsp60 significantly decreased at 45 days in the diaphragm, but not in limb muscles, in both trained and sedentary mdx compared to WT mice. In limb muscles, but not in the diaphragm, Hsp70 and NF‐kB p65 levels were increased in mdx mice irrespective of training at 30 and 45 days. Therefore, the diaphragm of mdx mice showed little inflammatory and stress responses over time, and appeared hardly affected by mild endurance training. J. Cell. Physiol. 232: 2044–2052, 2017.

Duchenne Muscular Dystrophy (DMD): Should it be Considered a Systemic Disease?

Duchenne muscular dystrophy (DMD) is an X-linked muscle disease characterized by progressive skeletal muscle loss and development of respiratory failure due to involvement of respiratory muscles. Similar to human DMD, the mdx mouse model lacks dystrophin but is characterized by relatively mild muscle injury, allowing testing the effects of mild endurance exercise training on dystrophic skeletal muscle. We were interested to study the effects of exercise training on airway cells in trained mdx mice by applying the same protocol previously tested in Swiss mice. We found that mdx mice showed little airway inflammation associated with training, but developed increasing apoptosis of airway cells over time, irrespective of the trained or sedentary status. These findings suggested subclinical progressive exhaustion of protective mechanisms in airway epithelium of the mdx mouse, possibly involving chaperonin Hsp60. Moreover, a paucity of goblet cells was shown in the airways of mdx mice at all-time points of the study, independently of the sedentary or trained condition. We speculate that a disturbance of the Notch pathway, which has already been described in dystrophic skeletal muscles, might be involved in the almost absent secretory cell phenotype found in the airways of mdx mice. Overall, our findings suggest that dystrophin might affect other tissues beyond skeletal muscles, and exert physiologic effects, which at present are poorly defined, in non-muscular tissues.

Endurance training: is it bad for you?

Educational aims To illustrate the characteristics of endurance exercise training and its positive effects on health. To provide an overview on the effects of endurance training on airway cells and bronchial reactivity. To summarise the current knowledge on respiratory health problems in elite athletes. Endurance exercise training exerts many positive effects on health, including improved metabolism, reduction of cardiovascular risk, and reduced all-cause and cardiovascular mortality. Intense endurance exercise causes mild epithelial injury and inflammation in the airways, but does not appear to exert detrimental effects on respiratory health or bronchial reactivity in recreational/non-elite athletes. Conversely, elite athletes of both summer and winter sports show increased susceptibility to development of asthma, possibly related to environmental exposures to allergens or poor conditioning of inspired air, so that a distinct phenotype of “sports asthma” has been proposed to characterise such athletes, who more often practise aquatic and winter sports. Overall, endurance training is good for health but may become deleterious when performed at high intensity or volume. Endurance training is good for health but may become deleterious when performed at high intensity or volume http://ow.ly/4n9jR4