I'm currently in a study for rasegillene and found your biocchemisstry lesson very
helpful, Thanks professor.
William Heitman wrote:
> List friends,
>
> I want to offer a short biochemistry lesson: (from better than a decade of
> memory-don't pick me too close). My purpose is to give you a working
> understanding of how the new medicines work.
>
> Dopamine is a chemical messenger between certain ("dopaminergic") nerve cells.
> It operates in the synapses (the tiny space that separates communicating
> nerves).
>
> Between normal cells, part of that dopamine is taken up and reused by the
> sending neuron. Another part is destroyed. Dopamine is broken down in the
> body by two enzymes-Mono Amine Oxidase (MAO) and Catachol -O- Methyl
> Transferase (COMT).
>
> General principle: when something is named an …ase, it is an enzyme. These
> are usually protein molecules. They often posses interesting chemical and/or
> mechanical properties They operate at the molecular level.
>
> Selegiline, (Deprenyl) is a selective MAO B (for brain) inhibitor. In the
> recommended doses, it does not bother MAO A which destroys dopamine in
> synapses outside the brain. The two COMT inhibitors we have now (Tasmar is
> available) are not selective. They decrease dopamine destruction in the whole
> body. Fortunately, there is carbidopa (blocks the enzyme that turns levodopa
> into dopamine outside the brain) in Sinemet. This prevents the accumulation
> of dopamine in the body outside the brain. Thus, elevated B/P, increased
> heart rate and other symptoms of excess dopamine do not have to be a problem.
>
> Summary:
> 1 Dopamine is broken down two ways: MAO and COMT
> 2 Deprenyl and Tasmar block these enzymes, respectively
> 3 The net effect is that of more dopamine.
> 4 Tasmar operates outside the brain as well as in the brain
>
> If you understand how this works you can understand how to use these new
> medicines. I prefer very slow changes. Hope you find this helpful.
>
> Regards,
> WHH 54/18
>
