Abstract
Background Acute pain events have been associated with persistent pain sensitization of nociceptive pathways increasing the risk of transition from acute to chronic pain. However, it is unclear whether injury-induced persistent pain sensitization can promote long-term mood disorders. The receptor tyrosine kinase FLT3 is causally required for peripheral nerve injury-induced pain chronification, questioning its role in the development of pain-induced mood alterations.
Methods In a model of paw incisional pain, mice underwent single (SI) or double incision (DI) and went through behavioral and molecular phenotyping with the evaluation of both sensorial and emotional pain components. The role of FLT3 was then investigated either by inhibition using transgenic knock-out mice and functional antibodies or by activation with FLT3 ligand (FL) administrations.
Results DI mice showed significant anxiodepressive-like and spontaneous pain behaviors while SI mice did not. DI also promoted and extended mechanical pain hypersensitivity compared to SI. This emotional and sensorial pain exaggeration correlated with a potentiation of spinal microglial activation after DI versus SI. Intrathecal minocycline, a microglial inhibitor, specifically reversed DI induced-mechanical hypersensitivity. Finally, FL injections in naive animals provoked mechanical allodynia and anxiodepressive-like disorders concomitant with a significant microglial activation while FLT3 inhibition blunted the development of persistent pain and depression after DI.
Conclusions Our results show for the first time that the repetition of a peripheral lesion facilitates not only exaggerated nociceptive behaviors but also anxiodepressive disorders. The inhibition of FLT3 could become a promising therapy in the management of pain sensitization and related mood alterations.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Conflict of interest statement: The authors declare no conflict of interests