Researchers at the University of Copenhagen have discovered the cause of the involuntary muscle contractions that patients with severe spinal cord injury often suffer, which may pave the way for new treatment methods. Involuntary muscle contractions, which may impair a patient’s quality of life, are due to the neurotransmitter serotonin that typically plays a crucial role in relation to a person’s voluntary control of movements, according to a Science Daily news report.

Research reveals that a group of cells in the spinal cord start supplying serotonin in an uncontrolled way after an injury, which may “knock” the motor system out of control. The Science Daily news report notes that the enzyme aromatic L-amino acid decarboxylase (AADC) plays an important role in the production of the neurotransmitter serotonin. Following a spinal cord injury, there is a rapid regulation of AADC, which results in the uncontrolled production of serotonin.

As such, Jacob Wienecke, PhD, says, “It is our guess that this is the spinal cord’s emergency response trying to boost the enzyme’s capacity.” According to the researchers, it may be the same emergency response that causes the involuntary movements that are also experienced by patients with Parkinson’s disease (PD), as indicated on the Science Daily news report. However, in PD patients, it is not the dopamine system that is affected but the enzyme, which activates the emergency response, is the same.

The Science Daily news report notes that the prospects of the study are interesting for both spinal cord patients and patients with PD.

Wienecke states, “It is an interesting perspective, which will hopefully focus efforts on targeting drugs specifically at the AADC cells. Perhaps in the future we can regulate the undesired neural activity in this way so that the unnecessary ‘disturbance on the line’ disappears for the affected patients.”

Wienecke adds, “Finding a solution to the problem is no easy task. However, a lot suggests that regulating serotonin production more precisely could mitigate undesirable spasms while also supporting the rehabilitation of controlled movements.”

[Sources: Science Daily, University of Copenhagen – The Faculty of Health and Medical Sciences]