Posted by amigan on October 27, 2007, at 20:19:09
In reply to Re: Dopamine agonists cause sedation. But why??, posted by linkadge on October 26, 2007, at 15:04:53
> Dopamine isn't necessarily a stimulating neurotransmitter. As mentioned previously, much of the actions that we associate with dopamine should really be associated with norepinephrine.
Ok.
> Most people think of certain drugs, ie caffiene, nicotine, amphetamines, ritalin, cocaine etc in terms of dopamine, when much of the energizing effect is probably due to norepinephrine.I see.
> We don't really have any pure dopamine reuptake inhibitors. Wellbutrin is as much stronger noradrenerigc effect than dopaminergic effect.We use to have one. Amineptine. And iirc, it was a mild stimulant.
> There are some investigational selective dopamine reuptake inhibitors which don't cause much psychomotor activation, but instead can produce drowsiness in human test subjects,
I'm not sure if this is 100% true. See Amineptine.
> Opiates are an example of drugs that have dopaminergic mechanisms but no noradreneric mechanisms. They can cause euphoria, and pleasure without necesarily producing stimulation.Opiates are not a good example imho... I think they cause sedation by activating the opioid receptors.
Imagine a drug that have strong antihistaminic properties and weak noradrenergic. That drug would have been a sedative despite its action on the NE. Perhaps nortriptyline is a good example to this.
> In certain areas of the brain, and at cetain receptors, dopamine causes inhibiton. The use of dopamine agonists in RLS, and Parkinsons is to produce inhibition. The use of stimulants in ADD can also produce inhibiton.
>
> It also depends on the receptor type too. I think the d1 and d2 receptors produce opposing effects on activation/inhibition.Interesting.
poster:amigan
thread:791344
URL: http://www.dr-bob.org/babble/20071027/msgs/791857.html