Neurotransmitter (X) Releaser Vs. Neurotransmitter (X) Agonist

[Jktm]

I'm assuming that a releaser would be a drug that actiually has the neurotransmitter as part of it's make up (i.e. the correct amino acid combinations (i.e. functional groups) in the molecule) and actually releases the neurotransmitter, of whatever it may be, directly into the blood as opposed to a drug attaching to a receptor in your brain and causing your axon terminals to release it, which would be an agonist of whatever neurotransmitter "X" is?

Just need to know for a paper I'm writing.

edit: or is it just agonists and antagonists?

edit2: sorry, writting a paper over neurochemistry and all I'm got is a semester and a half of general chem, one semester on psych, self education, and nothing worthy in biology or biochem...

 

[nAON]

A neurotransmitter releasing agent is gonna be a drug that causes the release of the neurotransmitter into synapse. An agonist binds to the postsynaptic receptor where it induces a nerve impulse. An antagonist does the same, except it blocks nerve impulses from being induced.

 

[kiwi-awoo]

No, it's kind of the other way round - a releaser doesn't contain the neurotransmitter, it realeases it by binding to transport proteins. An agonist binds to the same receptor that the neurotransmitter would to elicit a similar action as the neurotransmitter. An antagonist also binds to this receptor but doesn't activate it - meanwhile the neurotransmitter can't bind to it's receptor, blocking it's action.

 

[laCster]

This thread would probably be better suited for advanced drug disccusion

 

[sekio]

Quick and dirty example.

Amphetamine is a "releasing agent". It binds to the dopamine and norepinephrine transporter protiens (DAT/NET) that normally return dopamine and norepinephrine to a nerfve cell after it's fired. Once it's bound the protiens start releasing dopamine/norepinephrine, rather than returning it to the neuron.

Cocaine/methylphenidate are "reuptake inhibitors". They bind to the same transporter protiens as releasing agents, but don't cause the cells to release neurotransmitters spontaneously. Instead they simply prevent the neurotransmitter from being returned to the cell, so it acts much longer than normal when it is naturally released.

Drugs like pergolide are dopamine agonists. It binds directly to the same receptors dopamine binds to, and produces a similar effect.

Another example-
Releasing agent: MDMA
Direct agonist: LSD

All 3 classes of drugs produce distinct effects, and dno not neccesarily substitute for each other.