*5.2.4 Nrg1/ErbB2/3 signaling*

SCs express receptors for axonal neuregulins, as it is showed in Ssection 2.2. The neuregulin/Erb2/3 signaling is strongly involved in immature SC

#### *Demyelination Disorders*

development but not in the regulation of adult SC proliferation after injury. An *in vivo* study on erbB2 wt/lacZ (with highly reduced ErbB2 levels in adult sciatic nerves) mice showed that after sciatic nerve transection, SC proliferation is not affected in adult ErbB2-conditional null nerves. More of this, the maintenance of myelinated peripheral nerves did not require ErbB2 function [106]. Other studies demonstrated that ErbB2 activation after sciatic nerve axotomy induced SC demyelination [107].

Neuregulin Nrg1 is still necessary for adult SC evolution after nerve injury [108, 109]. The absence of Nrg1 in adult axons results in remyelination defects after nerve crush experiments and also in a slower axon regeneration [110].
