Do L-Dopa supplements stop endogenous synthesis of dopamine?

[leojay]

Hello, I've a pretty simple question which I'm having difficulty finding through google. (Can't figure out how to phrase it.) I was once told in a high-school biology class that L-Dopa is the last line of treatment for certain dopamine deficient related disorders because once your brain receives exogenous precursors it stops synthesis of L-Dopa. I can't find an article to confirm or dis-confirm this, so, if someone has an answer, I'd appreciate a source.
I ask because I'm considering some sort of dopamine regulation to help with ADD/lack of motivation and a friend suggested an herb "Mucuna phosphatidylserine" which I've read contains L-Dopa, I try and think about the long-term when it comes to my brain, I only have one.
I'm going to ask my DR if he will let me try PROVIGIL because I've heard great things as far as nerve-growth stimulation/attention/focus... I'm 27 now (I know that's still young but, I FEEL old) and I swear I feel a lull in my cognitive ability. I know its nature's plan to turn me into a potato in ~50 years, however, I'd like to do as much as I stop this without damaging myself.

Thank you VERY much to everyone who keeps this site up and running, neat and tidy. You're all my hero's. 's and photons -Leojay

 

[WSH]

I have never heard of L-Dopa stopping the synthesis of itself, you are talking about tyrosine hydroxylase inhibition, right?

The reason why L-Dopa is the last line of treatment is that it causes dyskinesias.

Dopamine agonists (e.g. ropinirole or pramipexole) are safer in this regard:

dopamine agonists have a longer duration of action and may be less likely than levodopa to evoke on/off effects and dyskinesias

Medical Management of Parkinson’s Disease

 

[dopamimetic]

I'm interested in this question too.

- Is L-Dopa really different from its serotonergic counterpart 5-HTP (which is usually considered to be relatively safe)?
I'd guess it's a) a matter of dosage and b) because L-Dopa usually gets used in people with pre-existing dopamine related dysfunctions. (And maybe c) that the dopamine system is more sensible to disruption because it is deeply involved with movements etc. causing dyskinesias vs. serotonin imbalance being more psychical in the first line)?

L-dopa is administered together with a peripherally acting decarboxylase inhibitor which greatly potentiates the amount that reaches the brain and gets converted to dopamine there. When using mucuna pruriens alone, an effective dose for Parkinson's is around 30 grams. With a mean dopa content of 4.5%, we have at least 1.35g of levodopa required.

I guess the same can be applied to 5-HTP - and nobody's gut will tolerate more than one gram of pure 5-HTP...
So, probably as with the vast majority of exogenous drugs, the body will adjust and dosage-related downregulation will occur over time. I doubt that the dopamine synthesis can be permanently halted in a healthy human just by using precursors. On the other side, small, sparingly used doses of any precursor shouldn't cause too much harm.

But of course any corrections are welcome!

 

[clubcard]

Interesting that L-DOPA has been abused. The first guy to screw himself with badly made MPPP (Barry Kidston) was taken OFF L-DOPA and onto something else because he was abusing it. His end came when he ODed on cocaine, so sounds like a stimulant fan. Interesting that the neutral amino-acid allows the stuff to cross the BBB.

It's certainly an interesting way to make legal prodrugs.

 

[leojay]

Thanks for the replies everyone!
my (probably wrong) understanding was that the dopamine system was more robust and accepting to changes in chemical concentrations because of the relatively short amount of time in which it takes for the system to go through changes. (compared to 5HT)
So I guess my question is: is dyskinesias inevitable in all cases? My main goal is nerve health/growth. And an increase in cognitive ability.(Like ever other part of the body, I understand diet and exercise are extremely important.)
I know there is no wonder drug pill/plant/powder/potion available or I would've heard of it. I suppose I should start hanging around the nootropic folk huh?