Figure 4.

Analysis of the muscle-specific motor-neuron populations in untrained and trained type 2 SMA-like mice. a–c, A loss of the soleus-innervating motor neurons, specifically labeled using a fluorogold retrolabeling technique, is observed in the spinal cord from untrained type 2 SMA-like mice (b) compared with trained type 2 SMA-like (c) and control mice (a) at 12 d of age. Scale bars, 20 μm. d, The quantification of surviving motor neurons innervating each muscle clearly indicates that the extent of motor neuron loss in type 2 SMA-like mice at 12 d of age is muscle-specific and that, in each muscle, the exercise protocol exerts an efficient neuroprotective effect in SMA (n = 6; *p < 0.05; **p < 0.01; ***p < 0.001).