Oral Treatments With the TrkB Ligand Prodrug, R13, Promote Enhanced Axon Regeneration Following Peripheral Nerve...

Area of Science:

• Neuroscience
• Regenerative Medicine
• Pharmacology

Background:

• Peripheral nerve injury often results in slow and incomplete axon regeneration, leading to poor functional recovery.
• Brain-derived neurotrophic factor (BDNF) and its TrkB receptors are crucial for enhancing nerve regeneration.
• Existing BDNF mimetics like 7,8-dihydroxyflavone (7,8-DHF) have limitations due to poor oral bioavailability and pharmacokinetics.

Purpose of the Study:

• To evaluate the efficacy of R13, a 7,8-DHF prodrug, as an oral therapy for promoting axon regeneration and functional recovery after peripheral nerve injury.
• To investigate the molecular and physiological effects of R13 on nerve repair mechanisms.

Main Methods:

• Sciatic nerve transection and repair model in mice.
• Single oral administration of R13 prodrug.
• Immunoblotting to assess TrkB, MAPK/Erk1/2, and AKT phosphorylation.
• Retrograde tracing to quantify motoneuron and dorsal root ganglion neuron survival.
• Electromyography (EMG) to measure functional recovery via M waves.

Main Results:

• R13 treatment led to rapid and sustained phosphorylation of TrkB and prolonged MAPK/Erk1/2 activation at the injury site.
• A significant increase in the number of retrogradely labeled motoneurons and dorsal root ganglion neurons was observed in R13-treated mice.
• Oral R13 significantly improved EMG responses (M waves) compared to vehicle or oral 7,8-DHF treatments.
• R13 demonstrated superior efficacy over oral 7,8-DHF in enhancing nerve regeneration and functional recovery.

Conclusions:

• The 7,8-DHF prodrug R13 is a potent oral therapeutic agent for stimulating axon regeneration.
• R13 effectively enhances functional recovery following peripheral nerve injury.
• R13 represents a promising therapeutic strategy for improving outcomes in patients with peripheral nerve damage.