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On Sun 18 Jul, George J. Lussier wrote: > Dear Colleagues, > A. What is meant by the term/concept of "up regulate" with regard to PD > medications? > B. The days here in New England have been hot and humid and I do a lot of > sweating but when the sweat flows into my mouth I can taste no salt. Is > there some kind of relationship between salt intake, depletion and how we feel? > > thanks....george > > > I wrote the attached response to George Lussier's question, but I have not seen my reply printed back to me as usual. Has anyone seen this e-mail before ? If my note really didn't get printed, what's going on? Has the Ken & Barb show finally taken over, and should we re-name ourselves the Parkinsn Lost? Bewildered of Derby This was my original note: -------------------------------------------------- > There were a lot of answers about question B, but I don't think I saw a reply to the question about "Up-regulation". As far as I know, the following is still the subject of lively debate among neurologists, and is by no means an accepted fact. Up- (and down)-regulation of dopamine We know that the production of dopamine is a controlled process, dedicated to producing the precise quantity of dopamine where and when it is required. This feed-back system is thought to be connected with two separate processes: Dopamine works by stimulating dopamine receptors on the target neurones. These target neurones can sense if their receptops are being over or under- stimulated, and regulate the production of receptors (which are being made and replaced all the time to compensate for this. This is called post-synaptic down (or up)-regulation, and operates over a period of days rather than minutes. I see this up- or down-regulation as the means by which the nervous system keeps the system in balance, even though the brain is slowly losing its complement of dopamine-producing cells. A much faster control system occurs because the neurone which makes and releases the the dopamine (the pre-synaptic neurone) also has dopamine receptors (called auto-receptors because they sense the amount of dopamine tthat the neurone has itself released. This information is then used to increase or decrease dopamine release, and is effective over short time- scales. This auto-receptor system is what i see as the means by which the brain tries to maintain a steady rate of flow of dopamine, I hope that is understandable: As I said earlier, this has the status of 'informed speculation' ---------------------------------------------- -- Brian Collins <[log in to unmask]>