The role of the desert hedgehog signaling pathway during degeneration and regeneration of peripheral nerves

The desert hedgehog (Dhh) signaling pathway is involved in the development of peripheral nerves (PNs). Dhh-null mice show abnormal neuronal development and perineurial barrier function. As it was previously shown that dhh is mainly expressed in developmental nerves and Sonic hedgehog protein (dhh homologous) has therapeutic effects in neuronal survival, we attempted to investigate the possible role of dhh signaling pathway in the nerve maintenance and repair after injury. Using RT-PCR and immunohistochemistry, we investigated the expression patterns of Dhh and its receptors (Patched-1 and 2, Smoothened) in postnatal and adult nerves of Wild type (WT) mice. The mRNA expression patterns of dhh and its receptors were investigated on crushed sciatic nerves of adult mice at different time points after injury (day 2, 7, 14, 28, 42). The DDY mice were anaesthetized with interaperitoneal injection of sodium pentobarbital and inhaled ether. All experimental protocols involving animals were approved by the committee of life science resource development research center of Kagoshima University. The expression patterns of dhh and ptc-2 are similar to the other two Schwann cell proteins (ciliary neurotrophic factor and myelin associated proteins), which have been shown to play role in nerve repair and survival. In conclusion, our results suggest a potential role for the Dhh-Ptc2 signaling pathway in the maintenance of PNs and nerve regeneration after injury.