Specific stimulation of migration of human keratinocytes by μ-opiate receptor agonists

There are several indications that neuropeptides, especially the opiate receptor agonists, modulate the immune response by stimulating the formation of granulation tissue and enhancing the reepithelialization. We observed that the μ-opiate receptor ligand β-endorphin stimulates the migration of cultured human foreskin keratinocytes. After 1 hour exposure to 1 μM β-endorphin, the keratinocytes experienced an increase of cell diameter by cellular elongation and stimulation of migration. Dynorphin had a lesser effect under the same condition. The opiate receptor antagonist naltrexone significantly reduced the effect of β-endorphin on keratinocyte migration. This migratory effect of μ-opiate receptor agonists in vitro indicates that the opioid peptides, released in wounds, could play a key role in the final reepithelialization and tissue regeneration in wound healing. This new knowledge will help us not only to understand the mechanism of wound healing but also to improve the therapeutic strategy in the healing of painful chronic wounds.