Posted by undopaminergic on June 6, 2008, at 9:25:17
In reply to Re: Question nr. 2!, posted by linkadge on June 5, 2008, at 18:45:15
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> I think its really about dose. I think too much ritalin like too much amphetamine will be neurotoxic. Whenever you take enough of the drug to promote the neurotransmitter release to get "high" you are probably risking neurotoxicity.
>Amphetamines and DAT-inhbitors produce some of the same neurobiological adaptions, such as downregulation of postsynaptic D2-receptors. However, the pattern of damage to presynaptic nerve terminals under discussion only occurs with amphetamines - at high doses - and not with cocaine or methylphenidate, even at massive doses, far beyond those used recreationally. In fact, the DAT-inhibitors protect against the toxic effects of high doses of amphetamines. High doses of DAT-inhibitors have the opposite effects of amphetamines in several respects - for instance, they produce increases in intracellular (vesicular) dopamine content, whereas amphetamines produce a depletion - including non-neurotoxic depletions at therapeutic doses, and this is one of the mechanisms underlying tolerance. It is not a matter of dose, but a matter of mechanisms of action.
For clarification, none of the above should be interpreted to mean that massive doses of cocaine or methylphenidate are harmless - they can be lethal in overdose, just like most other drugs. They can also produce tolerance and dependence, much like amphetamines do, but some of the mechanism are different and some of them are similar. It's also possible that they might promote certain types of neurotoxicity - but they are not capable of causing some of the types of damage seen with amphetamines.
poster:undopaminergic
thread:833007
URL: http://www.dr-bob.org/babble/20080606/msgs/833273.html