Leptin signalling promotes axonal regeneration in the peripheral and central nervous system [IFvAL RNA-seq]

Axonal growth is limited or absent following peripheral or central nervous system injury respectively, inhibiting repair. The identification of novel growth-promoting molecular mechanisms is therefore a priority. In the search for dietary-dependent mechanisms that control neuronal regenerative ability, we found, via RNA sequencing, that growth-promoting intermittent fasting (IF) induced leptin expression in sensory neurons of the dorsal root ganglia (DRG). Surprisingly, leptin signalling, whose canonical function is to control energy homeostasis, was critical for the IF-dependent regenerative phenotype. In fact, neuronal conditional deletion of the leptin receptor significantly impaired the regenerative response elicited by IF. Overexpression of leptin in vivo in DRG neurons enhanced axonal regeneration following peripheral sciatic nerve crush (SNC) and central spinal cord injury. Lastly, RNA sequencing following leptin overexpression in DRG neurons showed a significant increase in regenerative gene expression and transcription after SCI, indicating a role for leptin in inducing a euchromatic, transcriptionally active environment that facilitates nervous system repair after injury.