Stress hormone CRH helps brain repair myelin after injury

A stress hormone called corticotropin-releasing hormone (CRH) helps control the repair of myelin, the insulating sheath around nerve fibers, after brain injury, according to research published in Cell Reports on August 14, 2026.

Scientists at the Max Planck Institute of Psychiatry found that oligodendrocyte progenitor cells (OPCs) near damaged brain tissue produce CRH, which regulates the timing of their maturation into myelin-producing cells. Neurobiologist Jan Deussing and doctoral student Clemens Ries identified the cells after noticing a recurring response in mice with brain damage. Ries tested markers for all known cell types and found only OPCs responded. These precursor cells multiply around wound edges.

About one third of OPCs near an injury activate CRH within hours, but production stops after about three days, indicating a role in early healing. CRH receptor 1 (CRHR1) on a separate OPC population allows cells to respond to the hormone. When CRHR1 is absent, OPCs multiply faster after injury but ultimately produce fewer mature oligodendrocytes, leaving myelin repair incomplete. Myelin loss occurs in multiple sclerosis and physical injuries and can lead to neuron death.

During normal brain development, OPCs also build myelin from birth through young adulthood. Mice lacking CRHR1 produced more OPCs early in development and, as adults, had thicker myelin sheaths, especially around thin axons. That indicates CRHR1 on OPCs influences both injury repair and developmental myelination. The scientists hypothesize that developing neurons release CRH to regulate OPC multiplication and maturation.

Neurons are known to release CRH during stress, and early-life stress is a risk factor for psychiatric disorders. Deussing speculates that in stress-associated conditions such as depression, the CRH system in OPCs may play a greater role than previously known. If confirmed, the pathway could point to new therapeutic approaches.