Potential effect of mechano growth factor E-domain peptide on axonal guidance growth in primary cultured cortical neurons of rats

Establishing appropriate synaptic connections and plasticity is a critical need in neuronal regeneration and development. Mechano growth factor (MGF) and its C-terminal E-domain peptide with 24 amino acids, MGF-Ct24E, are potential neuroprotective agents. Our preliminary study indicates that Netrin-1 can guide axonal growth and its expression is sensitive to MGF, but how MGF regulates the expression of Netrin-1 and its receptor DCC is still unclear. Here, we investigate the effect of MGF-Ct24E on the expression of Netrin-1 and DCC in primary cultured cortical neurons in vitro and the adult rat brain in vivo. MTT assay shows that MGF-Ct24E can significantly protect primary cortical neurons against nerve injury. There is a significant increase in axonal elongation after MGF-Ct24E treatment at concentrations of 0.5 and 1.0 μg/ml. Real-time polymerase chain reaction assay indicates that MGF-Ct24E can effectively promote the expression of Netrin-1 and DCC in primary cultured cortical neurons. To identify the certain mechanism of MGF-Ct24E on neuronal guidance and growth, adult rats are subjected to intramuscular injection of MGF-Ct24E after traumatic brain injury. Rats injected with MGF-Ct24E start eating and drinking within 14 days, indicating that MGF-Ct24E can promote rehabilitation. HE staining and immunohistochemistry assays of brain section slices reveal that MGF-Ct24E treatment can significantly inhibit the haemorrhage of traumatic brain injury and promote expression of Netrin-1. Further investigation of protein expression by Western blot assay shows that MGF-Ct24E promotes expression of Netrin-1 and DCC after nerve injury. MGF-Ct24E can effectively improve axonal guidance through upregulation of Netrin-1/DCC signalling in neuronal regeneration.