The male sex hormone is important for the brain. Testosterone effectively helps repair myelin, which protects the nerve fibers in the organ.
Testosterone is definitely a multitasking hormone. Involved in male fertility, hair growth and muscle development, it is also essential for the brain. Inserm researchers have discovered that it is linked to the integrity of myelin. Its variations could therefore be involved in diseases such as multiple sclerosis, they explain in PNAS, the journal of the American Academy of Sciences.
The essential hormone
Myelin sheaths and protects the nerve fibers in the brain. It also ensures the rapid transmission of information sent by the brain or spinal cord to the rest of the body. It is therefore essential that it remains in good condition. To ensure this, two types of cells are involved in its repair: oligodendrocytes and astrocytes. The former are responsible for helping myelin to develop. A mending mechanism that is not flawless.
In multiple sclerosis for example, the sheath is damaged and the rest. Nerve transmission is therefore disrupted, which ultimately leads to paralysis.
Normally, a hormone helps the spontaneous repair of this sheath: testosterone and its receptor present in various organs. Tests on mice have confirmed this. Deprived of their testes or androgen receptors, the animals presented lesions in the myelin. “Testosterone promotes the production of myelin by cells which synthesize it in the central nervous system with the aim of repairing the sheath essential for the transmission of nerve impulses”, concludes Elisabeth Traiffort, research director at Inserm.
A common past
This “unexpected” discovery could prove invaluable to those specializing in demyelinating diseases, such as multiple sclerosis. Indeed, women are three times more affected than men, and the evolution varies according to sex. “Our results open the way to new therapeutic perspectives and could also be beneficial for research on psychiatric diseases or cognitive aging”, anticipates Elisabeth Traiffort.
It remains to explain how a sex hormone can be linked to such an important mechanism. The reason probably comes from the past. In the evolution of jawed vertebrates, the androgen receptor appeared along with myelin. A common story that would explain this unwavering bond.
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