Depression Neurotransmitter Synthesis from Amino Acids

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this fact are profound. The administration of only 5-HTP or L-dopa will compete with and inhibit the synthesis of the opposite precursor (dopamine and serotonin respectively) at the enzyme. 

Figure 3: The synthesis of serotonin, dopamine, norepinephrine, and epinephrine from amino acid precursors.

Depression Neurotransmitter Synthesis from Amino Acids

  The synthesis of serotonin and the catecholamines is illustrated in figure 3. Peripheral administration of only 5-HTP (serotonin system) or only L-dopa (dopamine system) will decrease the synthesis of the other system (dopamine or serotonin respectively).^57.  With administration of only one amino acid precursor, the administered amino acid precursor dominates the enzyme and compromises proper synthesis of the other system’s neurotransmitters.  This is due to the fact that the same enzyme catalyzes the conversion of 5-HTP-to-serotonin and L-dopa-to-dopamine everywhere in the body. 

  The aromatic L-amino acid decarboxylase enzyme is also known as 5-HTP decarboxylase enzyme or L-dopa decarboxylase enzyme, as well as the general decarboxylase enzyme, is illustrated in kidney in figure 4 below. The implications of this fact are profound.¹⁰ The administration of only 5-HTP or L-dopa will compete with and inhibit the synthesis of the opposite precursor (dopamine and serotonin respectively) at the enzyme. 

  In Parkinson patients, the long-term administration of L-dopa with insufficient serotonin precursor will result in depression. The literature is very clear that this depression is a serotonin dependent depression, which responds optimally to the most serotonin specific reuptake inhibitor, citalopram.¹¹

Depression Neurotransmitter Synthesis from Amino Acids

Figure 4: The neurotransmitters and amino acid are filtered at the glomerulous are uptaked in the proximal renal tubules by the cation ports of the proximal convoluted renal tubule cells. The proximal convoluted renal tubule cells then further filter the neurotransmitters and amino acids into separate areas where the neurotransmitters are metabolized and the amino acids are synthesized into new neurotransmitters that are then either excreted into the urine or secreted into the system via the renal veins.