Posted by Scott L. Schofield on January 29, 2000, at 13:14:15
In reply to Re: Tyrosine supplementation , posted by JohnL on January 28, 2000, at 18:02:37
> Whether tyrosine helps or not depends on whether the underlying problem is dopamine deficiency. Some depressions, anxieties, phobias, and schizophrenias can be caused by excess dopamine. Either a shortage or an overabundance will have undesirable psychiatric symptoms. If there is no dopamine deficiency to begin with, tyrosine supplementation will either do nothing or will produce uncomfortable results. On the other hand, if there is a dopamine deficiency, typrosine could work wonders. No way to find out I guess without trying.
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Hi JohnL.
Don't forget about norepinephrine.Norepinephrine was suspected to be involved in depression for at least 20 years before serotonin was. Nobody - well almost nobody - considered dopamine function to be at all important. Discussions involving dopamine were focused on its role in schizophrenia, and possibly in mania. It was norepinephrine that was the neurotransmitter most frequently targeted for investigation.
Tyrosine hydroxylase is the rate-limiting step for the manufacture of both norepinephrine and dopamine. I haven't heard of anything that would indicate that a rise in dopamine levels, to the exclusion of any changes in the levels of norepinephrine, would be one of the mechanism by which an improvement in mood occurs.
[L-Phenylalanine -> (l-phenylalanine hydroxylase) -> ] L-Tyrosine (tyrosine hydroxlase) -> L-Dopa (l-amino acid decarboxlase) -> Dopamine (dopamine -b-hydroxylase) -> Norepinephrine (phenylethanolamine N-methyltransferase) -> EpinephrineNorepinephrine=Noradrenaline
Epinephrine=Adrenaline
Maybe I've been a vegetable for too long, but I still have yet to read anything credible that purports to be able to explain affective illness in such simple terms as the "levels" of neurotransmitter found in either smashed brain tissue or cerebrospinal fluid.That said, I've heard of tyrosine augmentation being successful a number of times. I don't recall the details, but I know that it is important not to ingest any of several other amino-acids that would otherwise compete with if for passage through the blood-brain barrier.
I guess if you really wanted to go for it, L-dopa (with a peripheral decarboxylase inhibitor) might be interesting to try, as it is analogous to 5-HTP in the manufacture of serotonin.
- Scott
poster:Scott L. Schofield
thread:19759
URL: http://www.dr-bob.org/babble/20000128/msgs/20001.html