The synthesis of serotonin and dopamine are catalyzed by the same enzyme throughout the body, the Aromatic L-amino acid decarboxylase enzyme (AAAD).  The enzyme is found in numerous places in the body.

  5-HTP (L-5-HTP or 5HTP) is synthesized into serotonin without biochemical feedback inhibition. From a practical standpoint this means that as 5-HTP (L-5-HTP or 5HTP) dosing is increased serotonin will increase in direct proportion to the amount of 5-HTP (L-5-HTP or 5HTP) administered. With all observations made during this study this dose-response of 5-HTP (L-5-HTP or 5HTP) and serotonin was observed. L-dopa is synthesized into dopamine without biochemical feedback inhibition. From a practical standpoint this means that as L-dopa dosing is increased dopamine will increase in direct proportion to the amount of L-dopa administered. With all observations made during this study this dose-response of L-dopa and dopamine was observed.

  If synthesis of serotonin and dopamine from 5-HTP (L-5-HTP or 5HTP) and L-dopa respectively is not subject to biochemical feedback inhibition and levels of either serotonin and dopamine can be established as high as we wish with administration of amino acid precursors available over the counter in the United States why haven’t their use been shown as effective in treatment of disease or illness relating to low levels of neurotransmitters?” It is proposed that the reason for the lack of efficacy hinges on attempts to use only one amino acid precursor or the use of simultaneous amino acid precursors without properly balancing the amino acid precursors in the competitive inhibition state that exists in synthesis and transport between serotonin and dopamine discussed in this writing.

  With regards to the kidneys the literature notes, “the functional relevance of the competitive inhibitory effect of L-DOPA upon the decarboxylation of L-5-HTP (L-5-HTP or 5HTP) by AAAD is most probably meaningless; the concentrations of L-DOPA (at least 5 mM) needed to obtain a 30% reduction in the decarboxylation of L-5-HTP (L-5-HTP or 5HTP) are well above the levels of endogenous L-DOPA (- 10 gm).” This pertains to the synthesis of L-dopa and 5-HTP (L-5-HTP or 5HTP) into serotonin and dopamine respectively. In synthesis two distinct responses are seen the endogenous state and the competitive inhibition state. In transport two distinct states exist the endogenous state and the competitive inhibition state.

    The synthesis of L-dopa from tyrosine (L-tyrosine) is regulated by the norepinephrine tyrosine (L-tyrosine) hydroxylase feed back loop. tyrosine (L-tyrosine) hydroxylase is a quaternary ligand enzyme with four ligand (legs) binding points for norepinephrine. To completely shut down the tyrosine (L-tyrosine) hydroxylase enzyme four molecules of norepinephrine must bind one to each of the four ligand binding sites.  In the kidneys, this enzyme is found in the proximal convoluted renal tubules cells.  After uptake of the amino acid precursors into the proximal convoluted tubules, serotonin and dopamine amino acid precursors are synthesized into new serotonin and dopamine by AAAD.

  The concentration of the AAAD enzyme, as well as the MAO and COMT enzymes, which catalyze the metabolism of dopamine and serotonin, is highest in the brain and kidney tissue.  The synthesis of serotonin and dopamine from 5-HTP (L-5-HTP or 5HTP) and L-dopa respectively is subject a competitive inhibition state when levels presenting at the aromatic L-amino acid decarboxylase are higher than normally found in the endogenous state. In the when 5-HTP (L-5-HTP or 5HTP) and L-dopa levels are in the competitive inhibition state increasing the levels of one precursor will inhibit the synthesis from the other system. Administering only L-dopa without simultaneously administering properly balanced serotonin precursors will deplete serotonin. Administering only 5-HTP (L-5-HTP or 5HTP) without simultaneous administering properly balanced dopamine precursors will deplete dopamine.

  It has been observed in this study that once serotonin or dopamine is sufficiently depleted through administration of one amino acid precursors or administration of improperly balanced amino acid precursors of serotonin and dopamine, the desired effects of the other monoamine will no longer be observed. When sufficient depletion of one system is present is present in many cases increasing the serotonin or dopamine levels of the system not depleted may not restore desired effects of the other system. In subjects taking only one amino acid precursor of serotonin or dopamine increasing the single amino acid precursor may reinstate the desired effects. The restoration of the desired effects tends to be transient as depletion of the other system is accelerated with the increased dosing of only one amino acid precursor.

  The implications of this effect are observed in Parkinsonism treatment; when treatment with only L-dopa only stops functioning during the treatment of Parkinsonism, the standard approach in medicine is to increase the L-dopa dosing to restore the desired effects. This creates a cycle of tachyphylaxis, increased dosing of L-dopa, tachyphylaxis. In the course of this study it was observed that in L-dopa tachyphylaxis control of Parkinson symptoms may be reinstated with the administration of proper amounts of 5-HTP (L-5-HTP or 5HTP). In addition side effects associated with L-dopa treatment of Parkinsonism may dissipate as the L-dopa and 5-HTP (L-5-HTP or 5HTP) are brought into proper balance. The standard approach in treatment of Parkinsonism with L-dopa is to increase the L-dopa dosing repeatedly until a state is arrived at where the effects of L-dopa is no longer observed at any dosing level and the associated side effect multiply greatly. This state is associated with profound depletion of serotonin in the system.

  The amino acid precursors administered in this study were 5-HTP (L-5-HTP or 5HTP), tyrosine (L-tyrosine), and L-dopa. Combinations of amino acid precursors administered were the combinations “5-HTP (L-5-HTP or 5HTP) and tyrosine (L-tyrosine)”, “5-HTP (L-5-HTP or 5HTP) and L-dopa”, and “5-HTP (L-5-HTP or 5HTP), tyrosine (L-tyrosine), and L-dopa”.

  Daily amino acid dosing were amino acids obtained from the diet plus additional amino acid supplemental. It was found that dietary amino acid intake did not affect laboratory outcomes when significant amino acid precursor supplementation was in place, the driving force here being the supplemental amino acid precursors administered.

  Supplemental dosing range of 5-HTP (L-5-HTP or 5HTP) studied was zero milligrams per day to 3,000 mg per day. The data base mean 5-HTP (L-5-HTP or 5HTP) dosing was 600 mg per day with a standard deviation of 390.9 mg per day. It is noted that when subjects where taking no (zero) 5-HTP (L-5-HTP or 5HTP) in the study they were taking dopamine precursors only. While subjects taking no amino acids were studied these were not included in the data base for this paper.

  Supplemental dosing range of L-dopa was zero milligrams per day to 6,560 milligrams per day. The mean L-dopa dosing was 120 milligrams per day with a standard deviation of 190.1 mg per day. It is noted that when subjects where taking no (zero) L-dopa in the study they were taking 5-HTP (L-5-HTP or 5HTP) or 5-HTP (L-5-HTP or 5HTP) and tyrosine (L-tyrosine) in combination.

  Supplemental dosing range of tyrosine (L-tyrosine) was zero to 16,500 mg per day. The mean tyrosine (L-tyrosine) dosing was 5,500 mg per day with a standard deviation of 2,853.4 mg per day. It is noted that when subjects where taking no (zero) tyrosine (L-tyrosine) in the study they were taking 5-HTP (L-5-HTP or 5HTP) only.

  Direct assay of urinary serotonin and dopamine levels is of no assistance primarily due to the dilution (specific gravity) of the urine, which can vary widely. The assays in this study were reported as micrograms of serotonin or dopamine per gram of creatinine in order to compensate for urinary specific gravity variations.

  In general, it was found that once the amino acid dosing was started or the dosing was changed, it takes 3 to 5 days for equilibrium to be achieved regarding urinary serotonin and dopamine.

  Urine samples were collected approximately 5 to 6 hours before bedtime. For most patients, this represents a collection time of 4 or 5 PM. In shift workers or night workers, the collection times were adjusted accordingly. This is in direct contrast to previous assay of spot urinary serotonin or dopamine levels which are traditionally collected late in the morning. These traditional assays are used as a screening tool in order to determine if 24 hour urine collection is indicated in evaluation states of hyper-synthesis such as carcinoid syndrome or pheochromocytoma. Late morning urines are used to evaluate states where high levels of monoamines exist. Collection of urine to evaluate state traditionally associated with low levels of monoamines is optimal at 5 to 6 hours before bed time.

  The database used for analysis was queried in August, 2007 from a database containing over 12,000 serotonin and dopamine assays submitted by licensed caregivers for analysis. Accuracy of the data entry is described as exceptionally high. In tabling the data it was scrutinized at three separate steps by three separate individuals under a “zero tolerance of errors” approach. The August 2007 queries resulted in a study database consisting of 4,037 urinary serotonin and urinary dopamine assays. The queries used to define the final database studied were as follows.

  Data in the database had to be complete regarding the focus of the study. For example, if some or all of the required data from the caregiver was missing the data were excluded.

  Assays in which the subject was not simultaneously taking serotonin and dopamine amino acid precursors at the time of urinary sample collection were excluded.

  Outlier assays were excluded. An outlier is defined as, “a statistical observation that is markedly different in value from the others of the sample”. Outlier assays occur for a number of reasons, to include but not limited to the following. The subject missing one or more amino acid doses in the 5 days prior to collection of the sample. The subject has undergone a large stressor in the 3 or 4 hours prior to collection of the sample. For example, a subject who gets into a car accident on the way to the clinic in the late afternoon then has a urine sample collected in clinic may have abnormally high levels of monoamines on assay. The improper collection or transport of the samples may cause outliers.

  The outlier rate in the data base is 1.5%. In subjects with outlier rates of 10% to 15% or higher the leading cause of the outliers is missing one or more doses of amino acids in the five days prior to assay. Outliers due to missing amino acid dosing leads to problems in lab interpretation inducing need to additional testing and time to get amino acids and monoamines positioned in the desired response. As of recent a policy was adopted where all subjects will journal all pills with times taken in the week prior to urinary assay in order to address outliers.

  Subject samples with only one assay on file were excluded. This omission was necessary since definitive urinary serotonin and dopamine phase determination can only be made with two assays in comparison. 

  In figure 1 above is the urinary response when serotonin and dopamine are in the competitive inhibition state. The horizontal axis represents an increase in the total serotonin and dopamine amino acid precursor dosing 5-HTP (L-5-HTP or 5HTP) and tyrosine (L-tyrosine), 5-HTP (L-5-HTP or 5HTP) and L-dopa, or 5-HTP (L-5-HTP or 5HTP), tyrosine (L-tyrosine) and L-dopa) in combination or adding/subtracting just one precursor in subjects taking significant amounts of amino acid precursors. Observations are only valid if the subject is taking serotonin and dopamine amino acid precursors in combination and in the significant amounts associated with the competitive inhibition in the five days prior to sample collection. The vertical axis represents the urinary serotonin or urinary dopamine assay change between the first and second assay relative to the total dosing change in amino acid precursors, i.e. did the urinary serotonin or dopamine increase or decrease with increases or decreases of amino acid dosing.

  “Serial assay” is defined as two or more assays from one subject while taking different amino acid precursor doses at the time of collection of each sample assayed. Evaluation of serial urinary serotonin and urinary dopamine assays in subjects taking significant amounts of amino acid precursors in combination where the amino acid dosing was changed between assays revealed a “three phase urinary response” of serotonin and dopamine. Illustration of the three phase model is noted in figure 1 above. Key features of the three phase response model include the following.

  The phase of urinary serotonin and dopamine can only be determined using assays obtained while the subject is simultaneously taking significant amounts of serotonin and dopamine precursors associated with the competitive inhibition phase.

  In evaluating urinary serotonin and urinary dopamine assays, the three phase model of figure 1 applies to urinary serotonin and urinary dopamine independent of each other. During evaluation, urinary serotonin and urinary dopamine need to be individually conceptualized with their own version of the three phase model of figure 1 since the phases of urinary serotonin and urinary dopamine are independent of each other.

6

VALUES ESTABLISHED

  If urinary serotonin concentration is less than 800 micrograms of serotonin per gram of creatinine on any one assay, the subject is in phase 1. If the urinary dopamine is less than 475 micrograms of dopamine per gram of creatinine on any one assay, the subject is in phase 2. If the urinary serotonin is greater than 800 micrograms of serotonin per gram of creatinine the serotonin phase is either phase 1 or phase 3. If the urinary dopamine is grater than 475 micrograms of dopamine per gram of creatinine the dopamine phase is either phase 1 or phase 3.

  A method of determining the phase of urinary serotonin and urinary dopamine in phase 1 and phase 3 is determined by comparing the results of two urinary assays obtained while the subject is taking different doses of serotonin and dopamine amino acid precursors when each sample is collected then applying the model illustrated in figure 1.

  With administration of only 5-HTP (L-5-HTP or 5HTP) and tyrosine (L-tyrosine), dopamine levels over 475 micrograms of dopamine per gram of creatinine were never observed in phase 3. The embodiment of this is that when the only dopamine precursor administered is tyrosine (L-tyrosine) urinary dopamine levels over 475 micrograms of dopamine per gram of creatinine are phase 1 and levels less than 475 micrograms of dopamine per gram of creatinine are phase 2. When the only dopamine precursor administered is tyrosine (L-tyrosine) the only response of dopamine seen is phase 1 or phase 2. With administration of significant amounts of serotonin and dopamine precursors in combination establishing the competitive inhibition state, serotonin and dopamine have never been observed in phase 1 simultaneously. A method of determining serotonin and dopamine phase with one assay in subjects simultaneously taking 5-HTP (L-5-HTP or 5HTP) and tyrosine (L-tyrosine) is where the urinary dopamine is greater then 475 micrograms of dopamine per gram of creatinine and the urinary serotonin is greater than 800 micrograms of serotonin per gram of creatinine is the finding that dopamine is in phase 1 and serotonin is in phase 3. This observation is based on the fact that with administration of tyrosine (L-tyrosine) when administered as the only dopamine precursor will not establish phase 3 dopamine with administration of only tyrosine (L-tyrosine), and the observation that serotonin and dopamine are never found in phase 1 simultaneously.

  In this study it was observed with administration of L-dopa it is desirable to co-administer adequate amounts of tyrosine (L-tyrosine) simultaneously the L-dopa. Use of L-dopa as the only amino acid precursor may be associated with urinary dopamine levels that fluctuate significantly. Properly use of tyrosine (L-tyrosine) with L-dopa stabilizes urinary dopamine levels and prevents urinary dopamine fluctuations.

  The phases of urinary serotonin and urinary dopamine are independent of each other. For example, serotonin can be in phase 1 while dopamine is in phase 2 or 3 or dopamine can be in phase 3 while serotonin is in phase 1, phase 2, or phase 3. In a small percentage of cases, it may take three assays to determine the phase of urinary serotonin and dopamine.

7

THERAPEUTIC RANGES

  In treatment of subjects with this method the goal is to adjust amino acid dosing until relief of symptoms are seen or the urinary serotonin and dopamine are in the goal range which ever comes first. The standard urinary serotonin and dopamine goal defined by this study for adjusting amino acid dosing is a urinary serotonin in phase 3 within the range of 800 to 2,400 micrograms of serotonin per gram of creatinine and a urinary dopamine in phase 3 within the range of 475 to 775 micrograms of dopamine per gram of creatinine. A few examples of other goals ranges include treating Parkinsonism the phase 3 goal ranges is 800 to 2,400 micrograms of serotonin per gram of creatinine and the dopamine goal range is 6,000 to 8,000 micrograms of dopamine per gram of creatinine or the treatment of restless leg syndrome the phase 3 goal ranges is 800 to 2,400 micrograms of serotonin per gram of creatinine and the dopamine goal range is 1,800 to 3,000 micrograms of dopamine per gram of creatinine. Throughout this study goal ranges have been defined and refined as new data comes to light, the inclusion of these other goal ranges is to illustrated that goal ranges may differ depending on the process being addressed.

8

INTERPRETATION

  On the second assay, adding or subtracting only one amino acid precursor between assays will allow for determination of the phase of both serotonin and dopamine. For example, adding only 5-HTP (L-5-HTP or 5HTP) to the initial combination of serotonin and dopamine precursors will affect both serotonin and dopamine levels allowing for interpretation of both phases.  For example, with the addition of 5-HTP (L-5-HTP or 5HTP) to a urinary serotonin and urinary dopamine not in phase 2 if the second urinary assay shows the dopamine level decreasing, dopamine is in phase 1 on both the first and second assay, and the urinary serotonin level increasing the serotonin is in phase 3 on the second assay.

  Assay interpretation may be confusing for the inexperienced a few examples include the following. On the first assay a urinary serotonin of 3,000 micrograms of serotonin per gram of creatinine is found. Then 300 mg of 5-HTP (L-5-HTP or 5HTP) with 1,000 mg of tyrosine (L-tyrosine) and 360 mg of L-dopa are added to the amino acid dosing taken at the time of the first assay. On second assay urinary serotonin is once again found to be 3,000 micrograms of serotonin per gram of creatinine. This may lead to the interpreter to say, “What is going on here?” The answer lies in figure 1. The first serotonin assay was in phase 1 and the second serotonin assay was in phase 3. Urinary serotonin in phase 1 or phase 3 may change to phase 3 or phase 1 respectively with an amino acid dosing change completely passing through phase 2 if a significant amino acid dosing change is made. In general urinary serotonins less than 3,500 microgram of serotonin per gram of creatinine may be subject to this phenomenon although we have seen serotonins at higher levels subjected to this phenomenon as well when there is a steep slope in the urinary response to amino acids illustrated in figure 1. It is not uncommon to see urinary dopamines jump from phase 1 to phase 3 and miss phase 2 similar to the serotonin discussion immediately above but the magnitude of numeric change is not as great. Phase 1 or phase 3 urinary dopamines in the 500 to 800 microgram of dopamine per gram of creatinine range may be respectively in the phase 3 or phase 1 range of 500 to 800 microgram of dopamine per gram of creatinine range when significant amounts of L-dopa are added or subtracted from the total amino acid dosing.

  Embodiment of these concepts is as follows. The subject is taking 600 mg of 5-HTP (L-5-HTP or 5HTP) per day with 4,000 mg of tyrosine (L-tyrosine). The first assay reveals a urinary serotonin level of 8,365 micrograms of serotonin per gram of creatinine and a urinary dopamine of 232 micrograms of dopamine per gram of creatinine. At this point the serotonin phase is undetermined and the dopamine is in phase 2. The subject’s dosing of 5-HTP (L-5-HTP or 5HTP) and tyrosine (L-tyrosine) is maintained 600 mg 5-HTP (L-5-HTP or 5HTP) and 4000 mg of tyrosine (L-tyrosine) per day) and 360 mg/day of L-DOPA is added. On the second assay, the urinary serotonin is 3,102 micrograms of serotonin per gram of creatinine and the urinary dopamine is 734 micrograms of dopamine per gram of creatinine. Here, we have added only one amino acid precursor (L-dopa) to the initial combination of amino acid precursors administered. In the process, we are now able to determine the phase of both the serotonin and dopamine. The serotonin was in phase 1 on the first assay, it is in phase 1 on the second assay (increasing the total amino acid dosing led to a decrease in urinary serotonin). The urinary dopamine was in phase 2 on the first assay, it is now in phase 3 on the second assay.

  In general, human subjects were started on 300 mg of 5-HTP (L-5-HTP or 5HTP) per day and 3,000 mg of tyrosine (L-tyrosine) per day. From this starting dose, the amino acid dosing was titrated empirically at the discretion of the caregiver.  At a point determined by the caregiver when desired clinical results were not seen the caregiver began submitting urinary serotonin and dopamine samples for assay until desired results were observed or the urinary serotonin and dopamine was the desired range.

  A significant dose of amino acids is defined as amino acid precursor dosing high enough to allow for the competitive inhibition state to be observed as verified by the existence of the three phases of urinary serotonin and dopamine response of figure 1. The exact amounts of 5-HTP (L-5-HTP or 5HTP), tyrosine (L-tyrosine), and L-dopa dosing needed to affect competitive inhibition state observations is not a specific number applied to all individuals. The individual amino acid precursor dosing needs varies widely on a scale not previously known in the literature.

9

GROUP DOSING NEEDS

  Urinary 5-HTP (L-5-HTP or 5HTP) dosing with serotonin in phase 1 ranged from 38 mg to 1,500 mg per day with a mean of 338 mg per day and a standard deviation of 306.2 mg per day (N = 951). Urinary tyrosine (L-tyrosine) dosing with dopamine in phase 1 ranged from 750 mg to 11,500 mg per day with a mean of 4,000 mg per day and a standard deviation of 2,395.6 (N = 109). Urinary L-dopa dosing with dopamine in phase 1 ranged from 20 mg to 520 mg with mean of 160 mg per day and a standard deviation of 138.1 mg per day (N = 22).

  The 5-HTP (L-5-HTP or 5HTP) dosing in combination with balanced dopamine precursor needed to establish serotonin in phase 3 ranged from 37.5 mg per day to 3,000 mg per day with a mean dosing of 600 mg per day 390.9 mg per day (N = 2,060). The tyrosine (L-tyrosine) dosing range with dopamine in phase 2 (tyrosine or L-tyrosine) due to feed back regulation will not establish phase 3 dopamines) ranged from 375 mg per day to 16,500 mg per day with a mean of 5,000 mg per day and a standard deviation of 2,918.3 mg (N = 2,783). The L-dopa dosing range in combination with balanced 5-HTP (L-5-HTP or 5HTP) needed to establish dopamine in phase 3 ranged from 20 mg per day to 6,560 mg per day with a mean of 120 mg per day and a standard deviation of 134.3 mg per day (N = 1,116).

  It is noted that the amino acid precursor dosing needs for serotonin versus dopamine are independent of each other; meaning that in optimization the dosing needs of one precursor may be very low while the dosing needs of the other may be very high.

10

Tyrosine (L-tyrosine)

  N-acetyl-tyrosine is not tyrosine (L-tyrosine) and will not work in treatment. Norepinephrine regulates tyrosine hydroxylase. The tyrosine hydroxylase enzyme is not simply on or off with regards to function. tyrosine (L-tyrosine) hydroxylase is a quaternary ligand enzyme. For norepinephrine to completely shut down the tyrosine (L-tyrosine) hydroxylase four norepinephrine molecules must bind, one to each of the four ligand sites. If one, two, or three, of the ligand binding sites are bound with norepinephrine the enzyme is in a state of partial function. Complete shut down of the enzyme only occurs when a norepinephrine molecule binds to each of the four binding sites. The importance of this applies to the use of tyrosine (L-tyrosine) in combination with L-dopa under the assays described in this writing. The use of only L-dopa with 5-HTP (L-5-HTP or 5HTP) leads to significant fluctuation in dopamine assay results in some subjects. It was found that administration of tyrosine (L-tyrosine) with L-dopa control laboratory assay fluctuations. The model formulated in this study to explain the need to tyrosine (L-tyrosine) when L-dopa is administered to ameliorate fluctuations is as follows. L-dopa is synthesized to dopamine with biochemical feed back regulation. Dopamine is synthesized to norepinephrine without biochemical feed back regulation. In the past it was that that with the administration of L-dopa the tyrosine (L-tyrosine) hydroxylase enzyme was completely shut down. In the course of this study it was realized that the over all tyrosine (L-tyrosine) hydroxylase was only partially shut down and the urinary dopamine assayed needed to be viewed as from two sources to deal with laboratory flucuations on dopamine assay. One source of dopamine was from the L-dopa administered and the other source from tyrosine (L-tyrosine) administered or derived from the diet. Under the model developed it appears that the dopamine derived from tyrosine (L-tyrosine) fluctuates as the tyrosine (L-tyrosine) levels in the system change due to dietary intake and internal processes. This fluctuation of tyrosine (L-tyrosine) is magnified when L-dopa is administered leading to significant fluctuations in urinary dopamine assays in some subjects. By using a combination of tyrosine (L-tyrosine) with L-dopa flucuations of dopamine laboratory assays are controlled and stabilized. In adults the amount of additional tyrosine (L-tyrosine) with L-dopa needed for optimal group control of fluctuations is about 4,500 mg per day in addition to the routine amino acid dosing schedules developed in this study.