Effects of cutaneous receptor stimulation on muscular atrophy developed in hindlimb unloading condition

Abstract

The aim of this study was to investigate whether stimulation of the cutaneous mechanoreceptors of the rat foot sole could partially or totally prevent the soleus muscle atrophy developed after 14 days in hindlimb unloading conditions. Final experiments were achieved under deep anesthesia using pentobarbital sodium (60 mg/kg, ip injection). Atrophy was characterized by a significant decrease in muscle wet weight, fiber size, maximal twitch and tetanic tensions, contraction kinetics, and histochemical and electrophoretical changes. Our data demonstrate that the stimulation of these mechanoreceptors partially prevents the decrease in muscle weight (53%) and cross-sectional area of the soleus muscle (36%) and in all fiber types (type I: 31%; type Ic: 40%; type IIc: 49%; and type IIa: 44%) and also prevented the reductions in strength (peak twitch tension: 31%; peak tetanic tension: 25%). However, the decrease in contraction kinetics was not counteracted. Moreover, histochemical and electrophoretical changes were partially slowed. Thus our results suggest that stimulation of the sole mechanoreceptors can be used, in part, as a countermeasure to the muscular atrophy observed after a period of hindlimb unloading.

Physiologically adaptive changes of the L5 afferent neurogram and of the rat soleus EMG activity during 14 days of hindlimb unloading and recovery

“…In simulated microgravity, the patterns transmitted by these cutaneous receptors are likely to be disrupted because the soles of the feet are not in contact with the ground; consequently, the nervous motor message could be modified by the reflex pathway. The dynamic cutaneous mechanoreceptor stimulation of the plantar surface of the rat hindfeet during the 14 days of HU partially prevented soleus atrophy (De-Doncker et al, 2000;Kyparos et al, 2005). These studies demonstrated that, in HU condition, plantar cutaneous afferent information was decreased and participated in the development of muscular atrophy.…”

“…Consequently, the nervous motor message could be modified. This hypothesis has been confirmed by experiments that used the stimulation of plantar cutaneous mechanoreceptors, since the stimulation of these receptors during the HU period prevents 53% muscular atrophy (De-Doncker et al, 2000) indicating that plantar cutaneous information is greatly decreased during HU. Concerning the implication of proprioceptive information, Riley et al (1990) have observed that in HU conditions, the soleus was often in a shortened position as after tenotomy and immobilization in a plantar flexion position.…”

“…To date, no experimental studies have directly confirmed this assertion. However, some studies have demonstrated that hindlimb unloading is a particular environment that induces afferent feedback perturbations (De-Doncker et al, 2000;Falempin and InAlbon, 1999;Kyparos et al, 2005). In normal gravity, the maintenance of muscular properties depends, in part, on the feedback exerted by specific receptors: muscle spindles, Golgi tendon organs, and otolithic, articular and cutaneous receptors (Bock, 1998).…”

A gastrocnemius heterotopical transplant model with end-to-side neurorraphy

“…When the motor nerve was connected end-to-end to the sensory nerve ("Sensory protection"), it seemed to provide trophic environment to minimize muscle atrophy until a motor donor nerve became available. Although incapable of forming excitable neuromuscular junctions, sensory nerves were found to exert powerful trophic effects on denervated muscle fibers [12][13][14] .…”

Influence of fixed muscle length and contractile properties on atrophy and subsequent recovery in the rat soleus and plantaris muscles

“…Therefore, various preventive interventions can be implemented before exposure to the atrophic environment (Fujino et al, 2009) and during immobilization (De-Doncker et al, 2000;Kyparos et al, 2005). A previous study in the mouse immobilized the ankle joint at the maximum dorsiflexion and the maximum plantarflexion positions with a cast and assessed muscle atrophy in the tibialis anterior and soleus muscles (Fujita et al, 2009).…”