Differential adaptations during growth spurt and in young adult rat muscles

Abstract

During the post-weaning growth and maturation period (25/90 days after birth), rat limb muscles are submitted to specific adaptations. Our aim was to characterize the mechanical properties of two muscles that are opposite in terms of fibre-type distribution, the soleus and the extensor digitorum longus (EDL) muscles of male Wistar rats. Results showed a fast-to-slow fibretype transition in soleus while no modification in fibre-type distribution was observed in EDL. A growth-induced increase in muscle force was observed. Soleus underwent an increase in twitch kinetics, but EDL showed no modification. Resistance to fatigue was higher in 90-day-old soleus but not modified in the EDL. Surprisingly, analysis of maximal shortening velocity showed a decrease in both soleus and EDL. Finally, tension/extension curves indicated a growth-induced increase in series elastic stiffness in the two muscles. These results suggest that during this growth period, skeletal muscles are submitted to differential adaptations. Moreover, whereas adaptation of biomechanical properties observed can be explained partly by an adaptation of fibre profile in soleus, this is not the case for EDL. It is suggested that changes in muscle architecture, which are often disregarded, could explain some variations in mechanical properties, especially when muscles undergo an increase in both mass and length.

Effects of Growth on Muscle, Tendon, and Aponeurosis Tissues in Rabbit Shank Musculature

“…Summarizing the results of the age‐dependent studies, we did not identify studies that used the same animal and muscle types that were analyzed in the present study. However, quantitatively comparing these results with those obtained in previous experimental studies with rats (Lodder et al, ; Barros et al, ; Bénard et al, ) revealed similar relationships between the species during growth.…”

“…Age‐dependent measurements of morphometric and morphologic data during normal growth are rare. Independent of the degree of invasiveness, data have been collected from rats (high invasive) (Comer, ; De Koning et al, ; Heslinga and Huijing, ; de Haan et al, ; Tamaki and Uchiyama, ; Barros et al, ), rabbits (high invasive) (Crawford; 1950; Crawford, ; Alder et al, ; Crawford, ), and humans (non‐invasive) (Binzoni et al, ; Narici et al, ; Morse et al, ; O'Brien et al, ; Bénard et al, ; Yanagisawa et al, ; Weide et al, ).…”

“…Most previous studies have determined classic morphometric parameters, such as specimen length, weight, bone length and moment arm length during growth. In addition, muscle-specific quantities, such as the muscle volume, fascicle/fiber length, pennation angle, and anatomic or physiological crosssectional area, have been determined (Heslinga and Huijing, 1990;de Haan et al, 1992;Narici et al, 2003;Morse et al, 2008;Barros et al, 2009;O'Brien et al, 2010;Hiepe et al, 2014). Generally, the analysis of these parameters might reflect the fact that these indices can be determined using non-invasive methods, such as multi-dimensional ultrasound imaging or magnetic resonance imaging, in longitudinal studies (Fry et al, 2004;Barber et al, 2009;MacGillivray et al, 2009;Liaw et al, 2013).…”

Maternal voluntary physical activity attenuates delayed neurodevelopment in malnourished rats

“…, ; Barros et al . ). Pups from mothers submitted to protein malnutrition (7.8% protein) during lactation had delayed maturation of reflexes and a reduction in the time of exploration in the open field at 21 days of life (Barros et al .…”

“…Previous studies have shown that maternal malnutrition during pregnancy, lactation and early infancy can impair the development of brain structure and function, assessed as reduced cerebral vascularization and numbers of dendrites in rat offspring (Bennis-Taleb et al 1999;Barreto Medeiros et al 2002. Maternal low-protein diet during pregnancy and lactation results in disruption of the development of somatic features, ontogeny of reflexes and behaviour (Barreto Medeiros et al 2002Barros et al 2009). Pups from mothers submitted to protein malnutrition (7.8% protein) during lactation had delayed maturation of reflexes and a reduction in the time of exploration in the open field at 21 days of life (Barros et al 2006).…”