Dopamine is an important catecholamine monoamine neurotransmitter. Dopamine plays important roles in motor control, motivation, arousal, cognitive control, reinforcement, and reward. It is considered a stimulatory neurotransmitter.
Dopamine controls the brains voltage or power. The brains power determines the ability to:
- Stay focused
- Stay on task
- Accomplish a job or task
A deficiency of dopamine results in not enough maintenance of brain voltage, which is generally manifested as the brain slowing down and losing energy.
After age 45, the brain’s dopaminergic neurons age rapidly, causing a decline in dopamine levels of 13% per decade. [ [i] ] A drop in brain dopamine to 30% of the normal level leads to Parkinson’s, and a plummet to 10% results in death.
Dopamine - Voltage Change and Impact on Cognitive Abilities
Voltage Change Voltage Conditions
20 Superior energy and concentration
10 Normal energy and concentration
9 Fatigue, mild memory loss and cognitive deficit
8 Insomnia, panic disorder
7 Obesity, moderate obsessive-compulsive disorder, mild depression
6 Moderate addiction, major depression
5 Borderline personality disorder, chronic fatigue
4 Chronic depression, violent behavior
3 Attention deficit disorder
2 Alzheimer’s disease
The following physical manifestations are apparent with a deficiency of dopamine:
- Loss of mental intensity
- More time and effort needed to complete a task
- Less concentration (wandering mind)
- Decision making is not as fast
- Work intensity is diminished and slowed
Dopamine Deficiency Overall Symptoms Physical Symptoms
Confusion/Loss of Attention Addiction
Bone density loss
Difficulty achieving orgasm
High blood pressure
Inability to lose weight
Lack of quickness
Low sex drive
Poor blood sugar stability
Poor physical strength
Slow or rigid movements
Dopamine Precursors and Biosynthesis
There are three precursors to the neurotransmitter dopamine:
N-Acetyl-L-Tyrosine (NALT) can be substituted for L-Tyrosine and has better bioavailability while being able to cross the blood brain barrier better than L-Tyrosine.
D,L-Phenylalanine can be substituted for L-Phenylalanine.
L-DOPA is the direct precursor to dopamine and is able to cross the blood brain barrier. A natural high-yielding source of L-DOPA is Mucuna pruriens (Velvet Bean). The seeds of the plant contain about 3.1–6.1% L-DOPA and the leaves contain about 0.5% L-DOPA.
The sequence of the biosynthesis of dopamine is as follows:
L-Phenylalanine is converted into L-tyrosine by the enzyme phenylalanine hydroxylase (PAH), with molecular oxygen (O2) and tetrahydrobiopterin (THB) as cofactors.
L-Tyrosine is converted into L-DOPA by the enzyme tyrosine hydroxylase (TH), with tetrahydrobiopterin (THB), O2, and ferrous iron (Fe2+) as cofactors.
L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase (AADC; also known as DOPA decarboxylase (DDC)), with pyridoxal phosphate (PLP) as the cofactor.
Dopamine itself is also used as precursor in the synthesis of the neurotransmitters norepinephrine and epinephrine.
Dopamine is converted into norepinephrine by the enzyme dopamine β-hydroxylase (DBH), with O2 and L-ascorbic acid as cofactors.
Norepinephrine is converted into epinephrine by the enzyme phenylethanolamine N-methyltransferase (PNMT) with S-adenosyl-L-methionine (SAM) as the cofactor..
Deficiency in any required amino acid or cofactor will result in subsequent dopamine, norepinephrine, and epinephrine biosynthesis impairment and deficiency.
There are a few natural cofactors that assist in the biosynthesis of dopamine and are required by the various enzymes:
- Vitamin C (Ascorbic acid)
- Vitamin B6 (Pyridoxal phosphate (PLP, pyridoxal 5′-phosphate, P5P))
- S-Adenosyl methionine (SAMe)
Dopamine: Required Enzymes and CoFactors
Dopamine - Enzymes and CoFactors Amino Acid/NeuroT Enzyme Cofactor(s)
L-Phenylalanine phenylalanine hydroxylase (PAH) molecular oxygen (O2)
L-Tyrosine tyrosine hydroxylase (TH) tetrahydrobiopterin (THB)
ferrous iron (Fe2+)
L-DOPA aromatic L-amino acid decarboxylase (AADC; also known as DOPA decarboxylase (DDC)) pyridoxal phosphate (PLP)
Dopamine dopamine β-hydroxylase (DBH) L-ascorbic acid (Vitamin C)
Norepinephrine phenylethanolamine N-methyltransferase (PNMT) S-adenosyl-L-methionine (SAM)
Other than the three precursors that assist in the production of dopamine, namely, L-Phenylalanine, L-Tyrosine and L-DOPA, there are also certain natural substances that are recognized to enhance the production and function of dopamine.
Substances that May Enhance the Production and Function of Dopamine
Dopamine Category Nootropics/Nutraceuticals/Foods/Herbs Reference
Amino Acids Acetyl-L-Carnitine (ALCAR) 1
Herbs Ginko Biloba 3
Korean Ginseng 4
Siberan Ginseng 5
St. John’s Wort 6
Lipids DHA 7
Minerals Copper 9
Nootropics CDP-Choline 12
Nucleic Compounds NADH 15
Quinones Coenzyme Q10 17
Vitamins Alpha-GPC 18
Vitamin B6 19
Vitamin C 20
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