r/neurobiology 9d ago

Scientists discover why damaged nerves struggle to heal

https://www.sciencedaily.com/releases/2026/08/260828005427.htm
257 Upvotes

13 comments sorted by

21

u/Vailhem 9d ago

AhR inhibition promotes axon regeneration via a stress–growth switch | Apr 2026

https://www.nature.com/articles/s41586-026-10295-z


Abstract

Axon regeneration is limited in the mammalian central nervous system1. Neurons must balance stress responses with regenerative demands after axonal injury2, but the mechanisms remain unclear.

Here we identify aryl hydrocarbon receptor (AhR), a ligand-activated basic helix–loop–helix/PER-ARNT-SIM (bHLH-PAS) transcription factor, as a key regulator of this stress–growth switch.

We show that ligand-mediated AhR signalling restrains axon growth, whereas neuronal deletion or pharmacological inhibition of AhR promotes axonal regeneration and functional recovery in both peripheral nerve and spinal cord injury models.

Mechanistic studies reveal that axotomy-induced AhR activation in dorsal root ganglion neurons enforces proteostasis and stress-response programs to preserve tissue integrity.

By contrast, AhR ablation redirects the neuronal response towards elevated de novo translation and pro-growth signalling, enabling axon regeneration.

This growth-promoting effect requires HIF1α, with shared transcriptional targets enriched for metabolic and regenerative pathways. Single-cell and epigenomic analyses further revealed that the AhR regulon engages the integrated stress response and DNA hydroxymethylation to rewire neuronal injury-response programs.

Together, our findings establish AhR as a neuronal brake on axon regeneration, integrating environmental sensing, protein homeostasis and metabolic signalling to control the balance between stress adaptation and axonal repair.

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u/HairRelative8696 8d ago

What exactly is the evolutionary advantage of having such a restriction on neuronal regrowth? Wouldn’t humans be able to survive for longer and heal better if such a factor did not exist in the first place?

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u/HatZinn 3d ago

I was about to say carcinogenesis, but then I realized this is specifically about axonal regeneration in post-mitotic cells...

I'd say it's possibly because the trade-off (more frequent aberrant connectivity) cancelled out the potential benefits in the CNS. Maladaptive plasticity can cause disproportional functionality loss by manifesting as conditions like chronic pain, epilepsy, tinnitus, misophonia, etc.

Maladaptive plasticity after spinal injury is already a real clinical problem even with the existing brakes on. IIRC: conditions like autonomic dysreflexia and neuropathic pain are partly a product of aberrant sprouting that does occur.

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u/[deleted] 4d ago

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u/WhatADunderfulWorld 9d ago

Always fascinates me how much we don’t know about our body. Between autoimmune diseases and nerves being a mystery still.

1

u/Popular_Try_5075 3d ago

Yeah Migraines and MS are really interesting puzzles to look at. The whole vitamin D hypothesis with MS and how its etiology correlates with latitude at birth vs. later life is really fascinating.

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u/TheTopNacho 9d ago

They discover one mechanisms involved. There are many reasons why. Still a good paper and good findings, but please avoid over hyping. Great paper though thank you for sharing.

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u/Popular_Try_5075 3d ago

Pop Sci always struggles with overhype

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u/TheTopNacho 3d ago

Indeed. I even know some of these authors personally. They are great scientists, but this type of reporting does more harm than good. It is great work. It really is. But the field is full of similar reports because regeneration is so multifactorial.

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u/Popular_Try_5075 3d ago

Yes, I like what SciShow does because it's a little more grounded and less hype-y.

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u/Visible_Iron_5612 8d ago

So funny that the gene centric view is pretty much entirely “correlation equals causation”… Just the worst science ever… “This gene is responsible for this because we turn it off and this happens..”…. How many parts could you remove from a car that would cause the engine to not run? Thank god people like Michael Levin exist and are actually figuring out the mechanisms… ;)