Scientists Discover 'Biological Brake' That Blocks Nerve Regrowth After Injury

A new study has uncovered a key reason why injured nerves struggle to regrow. Researchers from the Icahn School of Medicine at Mount Sinai found that a protein called AHR acts as a 'biological brake' in neurons. This discovery, published in Nature, could lead to better treatments for spinal cord injuries and stroke recovery. The aryl hydrocarbon receptor (AHR) was first identified as a sensor for environmental toxins. But scientists now reveal it also controls how nerves repair themselves after damage. Normally, AHR forces neurons to prioritise survival over regrowth by protecting existing proteins instead of building new ones.

When AHR is blocked or removed, neurons start mass-producing proteins needed for axon growth. This shift allows damaged nerve fibres to regrow more effectively, improving motor and sensory recovery. The team also discovered that once AHR is deactivated, another factor called HIF-1α takes over. This activates metabolic genes that speed up tissue repair. The findings suggest that blocking AHR could help restore function after peripheral nerve or spinal cord injuries. Since AHR-inhibiting drugs are already in clinical trials for other conditions, researchers hope to fast-track testing for neurological diseases. Their next steps include trials of AHR-blocking drugs and gene-therapy strategies to boost axon regrowth in patients.

The study highlights a new way to potentially reverse nerve damage. By targeting AHR, scientists aim to develop treatments that improve recovery after spinal cord injuries, strokes, and other neurological conditions. Further research will determine how these drugs perform in human trials.