Posted by TRD_12 on July 30, 2012, at 5:41:53
In reply to Re: Abilify and dopamine release » SLS, posted by Phillipa on July 29, 2012, at 9:57:26
>I just don't see how an atypical antipsychotic could be effective as an antidepressant.
The antidepressant properties of atypicals are not limited to what you see. They are effective at treating negative symptoms just as antidepressants. The difference is that when used to treat depression as opposed to psychosis, lower doses are used, where they do not block D2-receptors hard enough to reduce dopamine output.
Let's look at quetiapine e.g. which I take. The antagonism at 5HT2A-receptor releases dopamine output in certain brain areas, this is why no EPS is seen at virtually any dose and the low incidence of TD. This dopamine release can help relieve depression the same way Wellbutrin does. Furthermore, quetiapine blocks 5HT2C-receptors which should release both dopamine and noradrenaline, which could contribute to antidepressant actions and cognitive improvement.
Then we have partial agonism at 5HT1A receptors, the same action that Viibryd and Buspar exert, which is thought to mediate anxiolytic and antidepressant effects.
Antagonism at H1 is great for insomnia and anxiety. Quetiapine's metabolite norquetiapine has noradrenaline reuptake inhibiting properties (NET), same mechanism seen with Wellbutrin, nortriptyline, reboxetine, Effexor, Cymbalta etc. It increases noradrenaline, and dopamine to some extent.
Actions at 5HT6 and 5HT7 receptors can also have positive effects on mood, sleep and memory.
Antagonism at adrenergic alpha 2 receptors (and through alpha 1) releases noradrenaline and serotonin.As you can see, Seroquel hits a myriad of receptors and affects NE, DA and 5HT in one way or another. Just because a med is labeled an antipsychotic doesn't mean it can't have other uses, such as antidepressants, anxiolytics and hypnotics.
Lamictal seems to prevent dopamine depletion.
Sources:
Stahl's books
Wikipedia
http://www.ncbi.nlm.nih.govHope that helps,
trd
poster:TRD_12
thread:1022353
URL: http://www.dr-bob.org/babble/20120718/msgs/1022414.html