A stress hormone may help the brain repair itself

When brain cells called oligodendrocyte progenitor cells (OPCs) detect damage, they show a surprising reaction. Within hours, about one-third of these cells activate corticotropin-releasing hormone (CRH), a stress hormone. This discovery was made by a researcher named Jan Deussing and his intern, Clemens Ries. Deussing had observed this response many times before but did not know the specific cells involved. Ries tested various markers and found that only OPCs produced CRH. This finding was published in Cell Reports.

CRH plays a crucial role in the timing of myelin repair. When CRH receptor 1, which is present on some OPCs, is absent, more OPCs multiply but fewer mature into oligodendrocytes that produce myelin. This suggests that CRH helps regulate the process of OPC maturation, which is essential for restoring damaged myelin sheaths. Myelin is vital for efficient nerve cell communication and healthy brain function. In conditions like multiple sclerosis, where myelin breaks down, restoring it is crucial.

Interestingly, OPCs also play a role in myelin development during normal brain development. Mice lacking CRH receptor 1 produced more OPCs during early development, leading to changes in myelin structure that persisted into adulthood. These changes resulted in thicker myelin sheaths, especially around thin axons. This indicates that CRH receptor 1 on OPCs might also influence myelin development from birth until young adulthood.

The researchers propose that neurons might release CRH during normal brain development, influencing OPC multiplication and maturation. This raises the possibility that the CRH system in OPCs could have broader implications for mental health, particularly in stress-associated psychiatric disorders like depression. Further research could lead to new therapeutic approaches targeting the CRH system in OPCs.