A “Brain Shield” for Tourette’s Patients

Tourette’s syndrome is a neurological disorder marked by stereotypic, involuntary, purposeless, and repetitive movements, often called tics. The exact pathogenesis of Tourette’s syndrome remains unclear until now. Haloperidol is an approved treatment for the symptoms of Tourette’s syndrome and other tic disorders. Though effective, most patients eventually discontinued the therapy because of its side effects, which include sedation and weight gain. Therefore, the development of new drugs for Tourette’s syndrome treatment is urgently needed. Fortunately, we have a really strong candidate — Gastrodin.

Gastrodin: the “Brain Shield”

The Chinese Herb, Gastrodia elata Blume (source: https://bluenanta.com)

Gastrodin, a phenolic glucoside, is the main active ingredient of traditional Chinese medicinal compound, Tianma. It is an active component of Gastrodia elata Blume, an herb that belongs to the Orchidaceae family. Traditionally, gastrodin is known for its beneficial effects on headache, migraine, dizziness, infantile convulsions, and tetany. It can improve the central nervous system ailments, like epilepsy, Alzheimer’s disease, Parkinson’s disease, cerebral injuries, and cognitive impairment. Along with its anticonvulsant property, gastrodin possesses antiepileptic, anxiolytic, anti-inflammatory, and antiobesity action. Other than that, gastrodin also promotes dopamine metabolism, helps in learning, and stimulates memory. Because of these properties, gastrodin is usually referred to as the “Brain Shield”.

The Chemical Structure of Gastrodin (source: https://www.selleckchem.com)

In China, gastrodin and its acetyl derivatives are commercially used as an over-the-counter drug to treat neurasthenia, headache, and migraine. In some other countries, it is available as a dietary supplement. However, gastrodin are mostly used as the main ingredient in brain-and-memory-booster supplements.

Why the “Brain Shield”?

While the exact cause of Tourette’s syndrome is still unknown, it is widely believed that the abnormality of the dopamine system plays a crucial role in causing this disorder. Dopamine is a neurotransmitter that gives a major contribution to the brain and body, including motor control. The particular dopamine-related substances involved in causing tics are the dopamine receptor D2 and the homovanillic acid.

Dopamine produces a remarkable effect when it binds to its receptor, Dopamine receptor D2, which is[AA1] made up of protein encoded by the DRD2 gene. DRD2 is the main receptor for antipsychotic drugs. It mediates cognitive flexibility and hyperactivity in humans. In Tourette’s syndrome patients, the DRD2 activity is higher than normal. Consequently, this makes the body’s dopaminergic neurons to be more hyperactive, causing a person to tic.

The Structure of Protein DRD2 (source: https://en.wikipedia.org)

After reuptake by dopamine transporters, dopamine was transformed into Homovanillic acid in neurons and released into the blood. Homovanillic acid or HVA is a major catecholamine metabolite of dopamine, used as a reagent to detect oxidative enzymes. The levels of HVA can indicate the dopamine activities in the brain. The low metabolism of dopamine can cause several problems to bodily functions, including one’s ability to initiate and direct muscle function and voluntary movements. The HVA levels of Tourette’s syndrome patients are lower than normal.

The Chemical Structure of HVA (source: https://en.wikipedia.org)

This is where the “Brain Shield” does its job. Gastrodin has the property to reduce seizure, modify noradrenergic, dopaminergic, and serotonergic neurons. It penetrates the blood-brain barrier, enters the central nervous system, and protects the nerve lesions. The key in controlling tics is promoting the metabolism of dopamine into HVA and inhibiting the DRD2 activity. With the property of modifying dopaminergic neurons, gastrodin should be able to help prevent it from abnormalities.

How Gastrodin “Shields” the Brain

Gastrodin carries its role in the dopaminergic neurons, located primarily in the dorsal regions of basal ganglia. It modifies the dopaminergic neurons by inhibiting their activity. Through this, gastrodin is limiting the interactions between dopamine and DRD2, making the neurons less hyperactive. Gastrodin also decreases the dopamine reuptake, promotes dopamine metabolism, and accommodates catecholamine in the nervous system. Promoting dopamine metabolism means the dopamine is able to produce more metabolites that are essential for the body to properly function, including the ability to control motoric movements. Altogether, gastrodin can successfully inhibit the stereotyped behaviors and alleviating Tourette’s syndrome symptoms.

Until now, Tourette’s syndrome is still deemed as an incurable disease. Nevertheless, there are many drug potentials out there that are yet to be further researched. Gastrodin can be the answer for Tourette’s syndrome patients to reach recovery. Furthermore, supplemental studies are needed for gastrodin to be used as a therapeutic agent for Tourette’s patients in years to come, for it is fundamental for every person to have freedom over their own body.

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References

Iino, Y., Sawada, T., Yamaguchi, K., Tajiri, M., Ishii, S., Kasai, H. & Yagishita, S. 2020. ‘Dopamine D2 receptors in discrimination learning and spine enlargement’, Nature. 579 (7800): 555-560.

Lambert, G. W., Eisenhofer, G., Jennings, G. L. & Esler, M. D. 1993. ‘Regional homovanillic production in humans’, Life Sciences. 53 (1): 63-57.

Lv, H., Li, A., Liu, F., Ma, H. & Yao, B. 2009. ‘Effects of gastrodin on the dopamine system of Tourette’s syndrome rat models’, BioScience Trends. 3 (2): 58-62.

Wang, Y., Zhao, L. & Li, A-Y. 2021. ‘Gastrodin – A potential drug used for the treatment of Tourette’s snydrome’, Journal of Pharmalogical Science. 145 (2021): 289-295.