endigenous neurotransmitters and drugs

[gib65]

Hi,

 

There seems to be a general principle that if a drug binds naturally to a neural receptor, then there must be indigenous neurotransmitters for that receptor. Some have argued that this means the drug can't be all that harmful. I'm just wondering how much truth there is to that. I mean, sure there might be a neurotransmitter that's naturally produced by the body which binds to those receptors, but the use of the drug brings on completely different effects, subjectively and behaviorally. In other words, the drug is mimicking the indigenous neurotransmitter in a very unnatural way or under very unnatural conditions.

 

Take cannabis, for example. THC binds to receptors that neuroscientists claim are designed for an indigenous neurotransmitter. However, I’ve NEVER experienced anything like the effects of marijuana under any condition other than when I smoke it, so if these indigenous neurotransmitters are supposed to occur naturally, why have I never experienced these effects naturally? Now, I've played around with a hypothesis that because getting high feels very much like a dream state, then maybe the indigenous neurotransmitter is responsible for making us dream. Whether or not my hypothesis is right doesn't matter. What matters is that, if this is true, this provides an example in which the use of marijuana would trigger the brain into going into a dream-like state in conditions under which it is not supposed to be dreaming - that is, the brain is still trying to process information coming in from the senses (usually dreaming is triggered well after the senses have gone into hibernation). So although THC might be mimicking this indigenous neurotransmitter, it is doing so under less natural conditions, and therefore might still pose a danger to the brain.

 

Does anyone think so?

[ashennell]

I'm not sure who has argued that this would not be that harmful. No drugs really mimic an indigenous neurotransmitter completely. Most neurotransmitters are released under tight control. They act on a very small local area and are removed quicky so there effect is temporary. Some neuromodulators have a more prolonged effect over wider areas. But these chemicals are released under specific circumstances and have a function.

 

Drugs that mimic these neurotransmitters are applied globally - the original function of the neurotransmitter is lost.

[badchad]

As ashennell said, just because a drug is natural, or binds to an endogenous receptor doesn't mean it is "safe" by any means.

 

But as far as your hypothesis is concerned it could be plausible. As far as human perception, cognition and consciousness is concerned there's no telling what may happen when particular neurotransmitter or receptor is stimulated. As another example, you could look at LSD (acid). We're fairly certain the primary effects occur through stimulation of serotonergic receptors (specifically 5-HT2A receptors) and its chemical structure resembles serotonin. However, it induces a conscious state well beyond what is considered "normal".

[shenzhou]

As another example, you could look at LSD (acid). We're fairly certain the primary effects occur through stimulation of serotonergic receptors (specifically 5-HT2A receptors) and its chemical structure resembles serotonin. However, it induces a conscious state well beyond what is considered "normal".

 

LSD seems to cause different effects in the cell than if the receptor is activated by serotonin. This is probably because the different chemical structures of LSD and serotonin interact with the receptor in different ways and this leads different effects on cells. Similar structures can give rise to quite different effects at the same receptor.

 

It must also be rememerbered that many poisons interact with normal receptors and that doesn't make them safe, or their effects normal.

 

It is probably the case that many drugs have evolved to target particular receptors present in many different organisms. For example nicotine probably evolved as a poison to insects but because our version of the receptor is different nicotine doesn't kill us (immediately) but has a drug type effect.

 

Serotonin Receptor Signaling and Hallucinogenic Drug Action: http://www.heffter.org/review/Review2/chap5.pdf

[ashennell]

However, they are still used in psychoanalysis... some... but it's mainly in pop psychology...

 

Nicotine can kill a human if you ingest a sufficient amount. I think the lethal dose is about 60 mg.

[aj47]

As our sanity partly relies on the balance of neurotrasmitters relased in our brain, taking substances that stimulate the release of neurotrasmmiters or act in the same way can cause a lot of problems. Although this most drugs only have a temporary effect on the levels of seretonin, dompanine etc and the real damage is on the effect that is has on your organs if taken in excess.

[ashennell]

Sorry, My last post dosn't make sense. I can't seem to editit now but should be -

 

For example nicotine probably evolved as a poison to insects but because our version of the receptor is different nicotine doesn't kill us (immediately) but has a drug type effect.

 

Nicotine can kill a human if you ingest a sufficient amount. I think the lethal dose is about 60 mg.