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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 18 of 18. This is the beginning of the thread.
Posted by clipper40 on November 13, 2007, at 3:24:10
I probably don't understand the meaning of an agonist correctly if I need to ask this question.
Posted by mav27 on November 13, 2007, at 6:24:30
In reply to Why aren't stimulants considered dopamine agonists, posted by clipper40 on November 13, 2007, at 3:24:10
Because they arn't agonists.
A dopamine agonist for eg is something that would bind to a certain receptor and fool it into thinking that dopamine had really bound to it.
Kind of like artificial/counterfeight dopamine i guess.Stimulants don't work that way although i don't really know how to describe how they work other than doing something to cause neurotransmitters like dopamine to be released by stimulating whatever releases them.
Posted by B2chica on November 13, 2007, at 8:03:13
In reply to Re: Why aren't stimulants considered dopamine agonists, posted by mav27 on November 13, 2007, at 6:24:30
sorry but i need some clarification. i understand that drug agonists and antagonists are binders, but i thought that an aganist binds to the receptor and infact stimulates the receptor (which would increase dopamine).an antagonist is a binder but doesn't stimulate the receptor (and this is where i am confusing with what you said) cuz i thought its the antagonist that sort of is a "fake" dopamine so to speak that attaches and 'tricks' the receptor into thinking it's what it is the dopamine....so that it doensn't accept more. (thus resulting in less dopamine activity)
could someone clarify for me?
curiously
b2c.
Posted by Phillipa on November 13, 2007, at 11:30:41
In reply to Clarification of Dopamine agonist/antagonist..., posted by B2chica on November 13, 2007, at 8:03:13
I don't get any of it not afraid to admit it. It would be nice to have a thread or a board where all this neurotransmitter stuff is explained properly. The big words only confuse me. And a book makes me close my eyes. I nursed but they never taught any of this. They would say oh an SSRI is a serotonin med more serotonin less despression. An add med is a med that works the opposite in some people and if they are anxious it calms them down. So I don't get it. I hyjacked your thread I think and apologize for that. Phillipa
Posted by B2chica on November 13, 2007, at 11:49:57
In reply to Re: Clarification of Dopamine agonist/antagonist... » B2chica, posted by Phillipa on November 13, 2007, at 11:30:41
DrBob at one time suggested a separate board but i and many others disagreed that it should be separate.
i like learning and in the beginning would have been too intimidated by a board like that.
Posted by Phillipa on November 13, 2007, at 12:11:24
In reply to Re: Clarification of Dopamine agonist/antagonist.. » Phillipa, posted by B2chica on November 13, 2007, at 11:49:57
Would you still be. Like the topic of the day could be what is serotonin. What does it do. Why do different people react differently. What meds contain it. Things like that the very basics not the technical stuff just for the layman so they can learn. A basic med education board. With questions and answers and if someone doesn't understand they would not be intimidated to say I don't understand is there a simpler way to put it? Love Phillipa still I've hyjacked your thread and that is not fair of me. Sorry again.
Posted by B2chica on November 13, 2007, at 13:38:22
In reply to Re: Clarification of Dopamine agonist/antagonist.. » B2chica, posted by Phillipa on November 13, 2007, at 12:11:24
i think the option DrBob presented was more of a 'higher level' of pharm discussion board.
but i like the idea of having a med board that had say a med of the week education topic. including not just med ed but also some A&P as well.
Posted by B2chica on November 13, 2007, at 13:45:44
In reply to Re: Clarification of Dopamine agonist/antagonist.., posted by B2chica on November 13, 2007, at 13:38:22
correction, i guess his suggestion was actually opposite of what i said, not a higher level but lower level...a beginner page.
most really liked the intermix of knowledge.what you suggested i think is different cuz its more of a ed board.(which i like)
and i think you should bring it up to dcBob on the Admin board.
HOWEVER, i doubt DrBob is going to recruit docs to post ed material and moderate each week...???here's the link to the admin board
http://www.dr-bob.org/babble/admin/20070817/msgs/788194.html
Posted by kaleidoscope on November 13, 2007, at 14:31:57
In reply to Why aren't stimulants considered dopamine agonists, posted by clipper40 on November 13, 2007, at 3:24:10
Stimulants such as Adderall are sometimes referred to as being indirect dopamine agonists because the drug molecule does not stimulate dopamine receptors directly, it stimulates them indirectly via in increase in synaptic dopamine availability. Stimulants also have numerous other actions involving other neurotransmitters.
True dopamine agonists such as Requip directly stimulate dopamine receptors ie. the drug molecule actually binds to dopamine receptors and stimulates them. This does not happen with the stimulants.
Posted by cumulative on November 13, 2007, at 16:21:34
In reply to Why aren't stimulants considered dopamine agonists, posted by clipper40 on November 13, 2007, at 3:24:10
It's just accepted nomenclature. Agonists in this connection typically refer to something that stimulates the receptor end -- dopamine agonists stimulate the activity of dopamine receptors. Stimulants work differently -- methylphenidate, for instance, blocks the reuptake of available dopamine, and amphetamine forces its release.
Posted by Phillipa on November 13, 2007, at 20:44:23
In reply to Re: admin discussion, posted by B2chica on November 13, 2007, at 13:45:44
Thanks just did. Phillipa
Posted by clipper40 on November 14, 2007, at 3:40:39
In reply to Re: Why aren't stimulants considered dopamine agonists, posted by mav27 on November 13, 2007, at 6:24:30
> Because they arn't agonists.
> A dopamine agonist for eg is something that would bind to a certain receptor and fool it into thinking that dopamine had really bound to it.
> Kind of like artificial/counterfeight dopamine i guess.
>
> Stimulants don't work that way although i don't really know how to describe how they work other than doing something to cause neurotransmitters like dopamine to be released by stimulating whatever releases them.
Thanks. I think I should have phrased my question differently and asked how stimulants work vs. how agonists work.
Posted by clipper40 on November 14, 2007, at 3:45:39
In reply to Re: Why aren't stimulants considered dopamine agonists » clipper40, posted by kaleidoscope on November 13, 2007, at 14:31:57
> Stimulants such as Adderall are sometimes referred to as being indirect dopamine agonists because the drug molecule does not stimulate dopamine receptors directly, it stimulates them indirectly via in increase in synaptic dopamine availability. Stimulants also have numerous other actions involving other neurotransmitters.
>
> True dopamine agonists such as Requip directly stimulate dopamine receptors ie. the drug molecule actually binds to dopamine receptors and stimulates them. This does not happen with the stimulants.
Ok, I understand. In the case of stimulants, does this apply to norepinephrine as well? Can you explain how stimulants indirectly force the release of more neurotransmitter? (If it's way too complicated, then don't bother.) Thanks.
Posted by clipper40 on November 14, 2007, at 3:49:10
In reply to Re: Why aren't stimulants considered dopamine agon, posted by cumulative on November 13, 2007, at 16:21:34
> It's just accepted nomenclature. Agonists in this connection typically refer to something that stimulates the receptor end -- dopamine agonists stimulate the activity of dopamine receptors. Stimulants work differently -- methylphenidate, for instance, blocks the reuptake of available dopamine, and amphetamine forces its release.
Thanks. I knew about the functioning of methyphenidate vs. amphetamines. What I didn't understand was the definition of an agonist. I thought an agonist was everything that caused release of neurotransmitter but I see now that it matters if it's directly or indirectly.
Posted by psychobot5000 on November 14, 2007, at 22:18:26
In reply to Re: Why aren't stimulants considered dopamine agon » cumulative, posted by clipper40 on November 14, 2007, at 3:49:10
> Thanks. I knew about the functioning of methyphenidate vs. amphetamines. What I didn't understand was the definition of an agonist. I thought an agonist was everything that caused release of neurotransmitter but I see now that it matters if it's directly or indirectly.
Pretty close, yeah. But technically, an 'agonist' doesn't cause release of neurotransmitters - rather, it's like they imitate them in certain places. As I understand it (this isn't likely to be perfect), neurotransmitters have their effects in our nervous systems by attaching to receptors located on nerves. If enough of the molecules attach at a time, then the nerve fires, sending a signal somewhere that has whatever effect. Meds like SSRIs or methylphenidate both are thought to work mainly through 'reuptake inhibition,' meaning that they block the reuptake 'transporter' for a given neurochemical - the thing that's in charge of scooping up excess serotonin, dopamine or whatever for disposal. With it blocked (the transporter), there's more of the chemical to hang around and make the nerves signal. That's how they change things.
Agonists are different. They don't directly change the levels of neurotransmitters. Instead, say, a dopamine agonist, will bind to some of the receptors (usually a post-synaptic receptor) that dopamine normally would, causing those nerves to fire more frequently. Thus, it's directly 'agonising' a nerve in the dopamine system ("dopamine agonist.")
In any case, the end result is usually quite different to just causing extra serotonin or dopamine or whatever to be released. I don't know why that would be entirely, but part of it is probably that a given 'agonist' doesn't necessarily act on all the nerves for a given chemical.
Hope that's helpful!
Posted by clipper40 on November 16, 2007, at 6:01:15
In reply to Re: Why aren't stimulants considered dopamine agon » clipper40, posted by psychobot5000 on November 14, 2007, at 22:18:26
> > Thanks. I knew about the functioning of methyphenidate vs. amphetamines. What I didn't understand was the definition of an agonist. I thought an agonist was everything that caused release of neurotransmitter but I see now that it matters if it's directly or indirectly.
>
> Pretty close, yeah. But technically, an 'agonist' doesn't cause release of neurotransmitters - rather, it's like they imitate them in certain places. As I understand it (this isn't likely to be perfect), neurotransmitters have their effects in our nervous systems by attaching to receptors located on nerves. If enough of the molecules attach at a time, then the nerve fires, sending a signal somewhere that has whatever effect. Meds like SSRIs or methylphenidate both are thought to work mainly through 'reuptake inhibition,' meaning that they block the reuptake 'transporter' for a given neurochemical - the thing that's in charge of scooping up excess serotonin, dopamine or whatever for disposal. With it blocked (the transporter), there's more of the chemical to hang around and make the nerves signal. That's how they change things.
>
> Agonists are different. They don't directly change the levels of neurotransmitters. Instead, say, a dopamine agonist, will bind to some of the receptors (usually a post-synaptic receptor) that dopamine normally would, causing those nerves to fire more frequently. Thus, it's directly 'agonising' a nerve in the dopamine system ("dopamine agonist.")
>
> In any case, the end result is usually quite different to just causing extra serotonin or dopamine or whatever to be released. I don't know why that would be entirely, but part of it is probably that a given 'agonist' doesn't necessarily act on all the nerves for a given chemical.
>
> Hope that's helpful!
Yes, that is very helpful! How exactly does the indirect agonist work then? Also, are there only three ways to influence neurotransmitter levels (real or by mimicking) in the brain (agonist, indirect agonist and reuptake inhibitor)?
Posted by psychobot5000 on November 19, 2007, at 17:18:59
In reply to Re: Why aren't stimulants considered dopamine agon » psychobot5000, posted by clipper40 on November 16, 2007, at 6:01:15
> How exactly does the indirect agonist work then? Also, are there only three ways to influence neurotransmitter levels (real or by mimicking) in the brain (agonist, indirect agonist and reuptake inhibitor)?
>Well, I'm out of my depth in trying to make an answer, but as I understand it, there are a bunch of ways drugs can act on these neurotransmitter systems - and the nerves they act on. And I believe researchers are still developing different ways for medications to act, too.
But, if I'm not wrong, 'indirect agonist' is a term that overlaps with reuptake inhibitors.
'Indirect agonist,' as I understand, is a term that applies to medications, which cause more neurotransmitter to be active, thus causing certain nerves to fire more often. So, indirectly, an SSRI 'agonizes' the nerves in serotonin pathways by causing more serotonin to be active in the synapse (the space between the nerve cells where serotonin does its signalling). By being a reuptake inhibitor, it's also an indirect agonist. I suppose some other drugs that increase available neurotransmitters through other actions, like causing more of them to be released, might also be indirect agonists...I'm not sure on that point.But there are many other ways of going about things. Valium and xanax don't directly agonize a nerve - they just attach to it and cause its receptors to change shape until they're more likely to be activated by other chemicals. Benadryl and other antihistamines are actually 'antagonists,' meaning they attach to the receptor, but don't cause it to fire - they just block it from being activated by anything else - in effect shutting the nerve down.
But another way meds can effect neurotransmitter levels is by attaching to a different type of receptor - an 'autoreceptor,' whose job it is (at least in some areas) to reduce neurotransmitter release if the levels get too high. So the drug activates it, and it reduces levels of neurotransmitter there.
As far as I can tell, it's all terribly complicated - though some of the posters on this site seem to have a pretty thorough understanding of these things. But of course, please take my words with a grain of salt - they're just my own imperfect understanding, and I may have made some errors (I hope not!).
P-bot
Posted by clipper40 on November 19, 2007, at 22:08:50
In reply to Re: indirect agonists and etc. » clipper40, posted by psychobot5000 on November 19, 2007, at 17:18:59
> > How exactly does the indirect agonist work then? Also, are there only three ways to influence neurotransmitter levels (real or by mimicking) in the brain (agonist, indirect agonist and reuptake inhibitor)?
> >
>
> Well, I'm out of my depth in trying to make an answer, but as I understand it, there are a bunch of ways drugs can act on these neurotransmitter systems - and the nerves they act on. And I believe researchers are still developing different ways for medications to act, too.
>
>
> But, if I'm not wrong, 'indirect agonist' is a term that overlaps with reuptake inhibitors.
> 'Indirect agonist,' as I understand, is a term that applies to medications, which cause more neurotransmitter to be active, thus causing certain nerves to fire more often. So, indirectly, an SSRI 'agonizes' the nerves in serotonin pathways by causing more serotonin to be active in the synapse (the space between the nerve cells where serotonin does its signalling). By being a reuptake inhibitor, it's also an indirect agonist. I suppose some other drugs that increase available neurotransmitters through other actions, like causing more of them to be released, might also be indirect agonists...I'm not sure on that point.
>
> But there are many other ways of going about things. Valium and xanax don't directly agonize a nerve - they just attach to it and cause its receptors to change shape until they're more likely to be activated by other chemicals. Benadryl and other antihistamines are actually 'antagonists,' meaning they attach to the receptor, but don't cause it to fire - they just block it from being activated by anything else - in effect shutting the nerve down.
>
> But another way meds can effect neurotransmitter levels is by attaching to a different type of receptor - an 'autoreceptor,' whose job it is (at least in some areas) to reduce neurotransmitter release if the levels get too high. So the drug activates it, and it reduces levels of neurotransmitter there.
>
> As far as I can tell, it's all terribly complicated - though some of the posters on this site seem to have a pretty thorough understanding of these things. But of course, please take my words with a grain of salt - they're just my own imperfect understanding, and I may have made some errors (I hope not!).
>
> P-bot
I figured that effecting the autoreceptors would be another way to go. Thanks so much for all of that information. I really appreciate you taking the time to spell it all out for me.C40
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