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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 13 of 13. This is the beginning of the thread.
Posted by B2chica on November 29, 2007, at 15:16:49
ok, so if i'm on a dopamine antagonist (good) which helps but that same drug is also a 5HT2 antagonist (specifically a and c), doesn't that mean it blocks the serotonin receptor?
so i would think that it would make depression worse or create depression if there were none. but it isn't/doesn't.
can anyone explain why? am i not understanding the function of the 5ht2 receptor right or is it that those specific ones (a and c)?
the AD i'm supposed to start (but havne't is actually an ssri).
any explanation by guru's here is appreciated.
or helpful websites too.
thanks
b2c.
Posted by James R on November 29, 2007, at 17:24:08
In reply to dopa antag, and 5-ht antag, posted by B2chica on November 29, 2007, at 15:16:49
very short:
in regards to the serotonin receptors, the 5ht-2a
action is anxiogenic and depressive. Activation of the 5ht-2a receptor reduces dopamine release across the brain and raises stress hormones
like CRF.So,blocking the 5ht-2a with an antagonist, or using an SSRI to downregulate the 5ht-2a can help
with anxiety, depression, and avoiding extrapyramidal side effects that could come
from the dopamine receptor block.James R.
> ok, so if i'm on a dopamine antagonist (good) which helps but that same drug is also a 5HT2 antagonist (specifically a and c), doesn't that mean it blocks the serotonin receptor?
>
> so i would think that it would make depression worse or create depression if there were none. but it isn't/doesn't.
>
> can anyone explain why? am i not understanding the function of the 5ht2 receptor right or is it that those specific ones (a and c)?
>
> the AD i'm supposed to start (but havne't is actually an ssri).
>
> any explanation by guru's here is appreciated.
> or helpful websites too.
> thanks
> b2c.
Posted by pstrait on November 29, 2007, at 18:10:29
In reply to Re: dopa antag, and 5-ht antag, posted by James R on November 29, 2007, at 17:24:08
it is helpful to keep in mind that the action of these medicines are all way downstream, so thinking along the lines of "serotonin = happiness" or whatever is invariably incorrect.
Posted by Phillipa on November 29, 2007, at 19:05:18
In reply to Re: dopa antag, and 5-ht antag, posted by pstrait on November 29, 2007, at 18:10:29
What meds are 5ht? Seriously don't know. Phillipa
Posted by B2chica on November 30, 2007, at 7:58:07
In reply to Re: dopa antag, and 5-ht antag, posted by James R on November 29, 2007, at 17:24:08
very short:
> in regards to the serotonin receptors, the 5ht-2a
> action is anxiogenic and depressive. Activation of the 5ht-2a receptor reduces dopamine release across the brain and raises stress hormones
> like CRF.
> So,blocking the 5ht-2a with an antagonist, or using an SSRI to downregulate the 5ht-2a can help
> with anxiety, depression, and avoiding extrapyramidal side effects that could come
> from the dopamine receptor block.this was just what i was hoping for. thanks james...but is the 5ht-2c receptor basically the same?
thanks!
b2c.
Posted by pstrait on December 1, 2007, at 0:13:37
In reply to Re: dopa antag, and 5-ht antag » James R, posted by B2chica on November 30, 2007, at 7:58:07
Im not sure the difference between 5ht2a and 5ht2c, but I know that the 5ht2c is often implicated in depression... a few studies have identified downregulation of 5ht2c receptors with the efficacy of ADs. Also, I think that 5ht2c receptor antagonism (or inverse agonism) releases dopamine.
Posted by anonymoose on December 1, 2007, at 12:24:40
In reply to Re: dopa antag, and 5-ht antag, posted by pstrait on December 1, 2007, at 0:13:37
Check the Summary of characterized 5-HT receptors, with selected high affinity agonist and antagonist ligands:
http://en.wikipedia.org/wiki/5-HT_receptor
I wish they'd list which are pre- and post-synaptic.Mirtazapine is a great example of a potent 5-HT2a and 2c antagonist, that for me could drive off a panic attack within an hour or two of ingestion. Unfortunately, it didn't do much else, and its adrenergic and antihistamine effects were just annoying.
Posted by Sigismund on December 1, 2007, at 15:31:47
In reply to Re: dopa antag, and 5-ht antag, posted by anonymoose on December 1, 2007, at 12:24:40
>Mirtazapine is a great example of a potent 5-HT2a and 2c antagonist, that for me could drive off a panic attack within an hour or two of ingestion. Unfortunately, it didn't do much else, and its adrenergic and antihistamine effects were just annoying.
The antihistamine effect is the sedation?
Does the adrenergic effect emerge through the sedation?
I've always associated adrenergic with stimulation.
I did enjoy the way it made sleep deeper.
Is that related to the 5HT2 a and c antagonism, rather than the antihistamine effect?
Posted by anonymoose on December 1, 2007, at 16:21:24
In reply to Re: dopa antag, and 5-ht antag » anonymoose, posted by Sigismund on December 1, 2007, at 15:31:47
> The antihistamine effect is the sedation?Yes.
> Does the adrenergic effect emerge through the sedation?At lower doses (<15mg) the effect of the H1 histamine antagonism is predominant. At higher doses, Mirtazapine becomes more activating as the alpha-adreno antagonism effects become more predominant.
> I've always associated adrenergic with stimulation.Yup. Though I've always found it to be a speedy, jumpy stimulation. NE is metabolized to epinephrine (adrenaline), and too much of it floating around in me led to this perpetual "fight-or-flight" state. Hypertensive effects were hellish, too.
> I did enjoy the way it made sleep deeper.
> Is that related to the 5HT2 a and c antagonism, rather than the antihistamine effect?Not sure what's behind the deep sleep, crazy vivid dreams, and deep brain fog upon wakening. Anyone else?
Posted by B2chica on December 3, 2007, at 13:12:09
In reply to dopa antag, and 5-ht antag, posted by B2chica on November 29, 2007, at 15:16:49
found this....about the 5-HT2A receptor...i think answering my question as to why the componenets of olanzapine actually help rather than hinder my depression.
"Increased stimulation of 5-HT2A receptors seem to oppose the therapeutic actions of increased stimulation of other serotonin receptors in anti-depressant and anxiolytic treatments."
Posted by pstrait on December 3, 2007, at 20:55:27
In reply to Re: dopa antag, and 5-ht antag, posted by B2chica on December 3, 2007, at 13:12:09
but wouldn't the olanzapine stop stimulation of the 2a receptors? I thought it was an antagonist.
Posted by anonymoose on December 3, 2007, at 22:36:49
In reply to Re: dopa antag, and 5-ht antag, posted by B2chica on December 3, 2007, at 13:12:09
> found this....about the 5-HT2A receptor...i think answering my question as to why the componenets of olanzapine actually help rather than hinder my depression.
>
> "Increased stimulation of 5-HT2A receptors seem to oppose the therapeutic actions of increased stimulation of other serotonin receptors in anti-depressant and anxiolytic treatments."5-HT2a is a main excitatory serotonin receptor, and stimulation (or *agonism*) of it triggers neuronal excitation and anxiety, among other things.
5-HT2a blockade, or *antagonism*, decreases anxiety.
I'm not too sure about olanzapine, but I thought it was an antagonist at 2a and 2c sites. The 2c antagonism, specifically, is what is implicated in weight gain. (Same with mirtazapine.)
Are you taking olanzapine or the olanzapine-fluoxetine combination (Symbayax?)
When SSRIs increase synaptic serotonin, one undesired consequence is increased stimulation of the 2a/2c receptors. This increased stimulation of excitatory serotonin receptors is what's implicated in SSRIs' paradoxical effect of actually increasing anxiety and suicide risk within the first few weeks. It's not until the 2a/2c receptors start to downregulate/desensitize that anxiolytic effects are felt.
Posted by B2chica on December 5, 2007, at 12:49:10
In reply to Re: dopa antag, and 5-ht antag » B2chica, posted by anonymoose on December 3, 2007, at 22:36:49
just olanzapine
>>>When SSRIs increase synaptic serotonin, one undesired consequence is increased stimulation of the 2a/2c receptors. This increased stimulation of excitatory serotonin receptors is what's implicated in SSRIs' paradoxical effect of actually increasing anxiety and suicide risk within the first few weeks. It's not until the 2a/2c receptors start to downregulate/desensitize that anxiolytic effects are felt.
D@MN!!!
i wish i had known this a couple years ago....this is EXACTLY what happened to me..and landed me my very first visit to the ER. i tried and tried to tell the doctors it was the med i was on and they wouldn't listed to me, and wouldn't take me off it FINALLY after two weeks in the hospital my doc had a weekend off and the on-call doc saw me i told him I WANT OFF cymbyax and he agreed....THREE freaking days later i was out!yes it is an antagonist for 2a and 2c. i think i'm confusing myself with my own posts...did i write something contrary to that?? sorry for my bad.
thanks for your input anonymoose.
b2c.
This is the end of the thread.
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