Posted by scott-d-o on January 27, 2004, at 22:10:35
In reply to Do anti-psychotics act on dopamine the same as..., posted by jerrympls on January 27, 2004, at 20:22:46
antipsychotics are dopamine antagonists and sometimes have effects at a bunch of other receptors as well, usually in hopes of reducing the risk of tardive dyskinsia.
of the drugs you mention, one of them, mirapex, is a dopamine agonist, and the other is an indirect dopamine agonist; really it is the opposite action from antipsychotics.
however, your pdoc is right that at *low doses* antipsychotics can increase dopaminergic transmission because they antagonise these receptors in yo brain called presynaptic or "autoreceptors." These receptors are located on dopamine-producing neurons and act as a feedback mechanism for how much dopamine is in the synaptic space (i.e. between neurons.) antagonizing *these specific receptors* causes the neuron to release more dopamine, therefore there is more dopamine in the synaptic space to "agonize" the postsynaptic receptors naturally.
you just have to be careful because some antipsychotics don't preferentially antagonise autoreceptors at any dose, and in any case, taking a dose past the point where more postsynaptic receptors are being antagonized than presynaptic ones can really f*ck up a person who has a dysfunctional dopaminergic system (ask me how I know)....
dopamine agonists *may* actually cause a *decrease* in dopamine transmission using the same logic.. obviously higher doses would be desirable in their case if increasing dopamine transmission is your goal.. understand?
scott
poster:scott-d-o
thread:306217
URL: http://www.dr-bob.org/babble/20040127/msgs/306258.html