Figure 6.

Absence of CLU in SCs impairs regeneration of peripheral sensory axons: Sensory axon regeneration, thermal recovery and reinnervation of peripheral sensory targets are impaired in CLU^−/− mice 4 weeks after sciatic nerve crush. a, The latency to withdrawal time to thermal stimuli of paws ipsilateral to the injury is increased in CLU^−/− mice compared with CLU^+/+ mice, demonstrating reduced sensory recovery in the absence of CLU. In addition, the total number of myelinating axon profiles present in sural nerves (b, c) and the number of intraepidermal nerve fibers present in a 3 mm segment of footpads ipsilateral to the nerve crush (d, e) were significantly reduced in CLU^−/− mice, compared with CLU^+/+ mice. The impaired sensory nerve regeneration in CLU^−/− mice appears to be due to the loss of CLU specifically within SCs, as the regeneration of sensory axons through peripheral nerve grafts from CLU^−/− mice was impaired. There were fewer sensory neurons retrogradely labeled with fluorogold in the CLU^−/− grafts compared with the number of retrogradely labeled neurons in CLU^+/+ grafts (f). Regeneration of motor neurons in CLU^+/+ and CLU^−/− was similar 4 weeks following sciatic nerve crush (g). Similar numbers of intact NMJs (gray bars), partially reinnervated NMJs (white bars), and remaining denervated NMJs (black bars) in EDL and SOL hindlimb muscles (p ≥ 0.05 for intact, partially reinnervated and denervated NMJs). Scale bar, 20 μm. *p ≤ 0.05 and error bars indicate SEM.