Dopamine receptor D2
Dopamine receptor D2 (DR2) is the major dopamine receptor in the brain and is encoded for by the DRD2 gene 1. As a dopamine receptor DR2 plays an important role in many physiological processes including movement 2, mood 3, cognition 4 and reward behaviour processing 5.
There is one SNP in DRD2, C957T, which is associated with a reduction in DR2 expression in the brain, and therefore alterations in mood and other cognitive functions.
|rsID Number||Major Allele||Minor Allele||Minor Allele Frequency (%)||Major Amino Acid||Minor Amino Acid|
The risk ‘T’ allele of C957T in the DRD2 gene is associated with reduced levels of dopamine receptor expression in the brain, and altered cognitive processes including altered levels of focus, stress and multitasking capacity 6. There is also some evidence that this allele may be associated with an increased risk of developing neurological conditions such as schizophrenia 7.
It is thought these reduced levels are modulated through changes in the expression and localisation of D2R in the striatum region of the brain. Those carrying the risk ‘T’ allele showed reduced expression of D2R in the striatum which was modulated by a reduction in mRNA stability.
Tyrosine is one of the standard 20 amino acids used by cells to form all the proteins required for health.
While used throughout the cells of the body tyrosine is especially important in the brain as it is a key precursor for many neurotransmitters and hormones such as dopamine 8. Tyrosine is converted into dopamine by tyrosine hydroxylase, which can then be further converted into other neurotransmitters.
For those carrying the risk allele ‘T’ of C957T in the DRD2 gene, who demonstrate reduced levels of dopamine in the brain, supplementation may therefore prove beneficial.
A 2016 study demonstrated that a 2g dose of tyrosine 1 hour before testing significantly improved the cognitive performance of those carrying two copies of the risk ‘T’ allele. Unfortunately, the authors didn’t take this further and investigate the benefits of a sustained (and likely lower dose) supplementation 9.
Discuss this information with your doctor before taking any course of action.