Dear Brian, Your thoughtful response arrived at my house and I do apologize for not getting back to you sooner. There was no other response and I must admit that there was no serious response to the other question. I passed out your explanation of "Up-Regulate"to several people including my neurologist who used the term at my support group's last meeting. But he is on vacation until next week. When I have at least a couple of responses I will let you know by posting to the list. I think the term means different things to different people. One thing to a cancer researcher; another to a neurologist with no research interests. I searched any number of on-line dictionaries and could find no listing. Lots of use but no explanation/definition I do thank you for your response Best george At 01:40 AM 7/22/99 +0100, you wrote: >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]> > > "It is better to keep your mouth shut and appear stupid than to open it and remove all doubt." --Mark Twain