Anyone here know anything about receptors in your brain?

[Taverner]

That is, opioid receptors, cannabanoid receptors, etc

How exactly do they work? Can you trick them into "thinking" they are being hit by an agonist (or antagonist)?

[DeeJay]

1. What do you mean "trick" them?

Basically that's what drug discovery is about, finding small molecules that bind to certain receptors. But I don't think that's exactly considered "tricking" them.

:shrug:

What do you want to know, actually?

[Taverner]

3. How does the process work?

Do the molecules bind themselves to said receptors?

[DeeJay]

4. It depends on the receptor and the agonist/antagonist

But in general, yes. What varies is the affinity of the receptor for the molecule(s). Also, there are different types of receptors in terms of what they actually do when they have their ligand bound -- they might be a pore-like structure that allows ions (eg, Ca++) in or out, they might trigger some other biochemical reaction inside the cell when the receptor is bound (or unbound), etc.

Is there something specific you want to know? Ask, I'll point you in the right direction.

[Taverner]

7. I'm weaning off pain meds, and I just want to know how it all works

Curiosity, that's all

[DeeJay]

8. OK. Well, what is probably interesting to you is that

for certain receptors (such as opiates), the more binding they do to ligand, the more feedback there is to make more receptors, which is why people have to take more drug to get the same effect over time. Then, when you stop taking meds, you have a period of time where you have more receptor than you have ligand (endogenous, made by your body, such as endorphins) and that's what causes the symptoms of withdrawal (think of hungry receptors not getting fed).

That's a very simplified answer to a very complex system though. Each receptor family can have several subtypes and they all can interact, so in many cases, the picture is still far from clear.

Just know that over time, the receptor balance should return to normal levels

[Taverner]

10. Cool! What I don't get is the difference between and antagonist and an agonist

[DeeJay]

11. Oh. An agonist is something that mimicks the natural ligand

An antagonist is something that has the opposite effect. So, an antagonist that binds to a receptor actually blocks the agonist from being able to bind, while also not sending the same signal that the bound agonist would send. It's a way of blocking a receptor's natural effect.

Sometimes a molecule can be an agonist at one concentration but an antagonist at another. Again, it can be complicated.

[Taverner]

12. Definitely!

So what is it that makes a molecule an antagonist in one concentration, but an agonist in another?

Is it some response from a high or low dose that does it?

[leveymg]

2. Do you want to trick them into thinking you're stoned, or not stoned?

If the latter, just tell them, "I didn't inhale." That works, sometimes.

If the former, just stop inhaling. For real. You'll see stars, and streaks, and have this fuzzy swooning feeling . . . nighty, night.

[Rabblevox]

5. That's exactly how Naltrexone works...

Nalterxone is an opiate blocker. It "fits" the opiate receptors in the brain, thereby blocking real opiates. You can literally shoot heroin all day long without getting high.

http://en.wikipedia.org/wiki/Naltrexone

I'm no scientist, but I would guesss cannabanoid receptors function similarly.

[DeeJay]

9. It's true in the sense that both are the same type of receptor

called G-protein coupled receptors (GPCRs). These receptors have 7 "transmembrane" regions, which means it passes in and out of the cell membrane 7 times. They work by changing the intracellular concentration of calcium. The top image is a cannabinoid receptor (2 actually) and the bottom is opiate. But keep in mind that each of the "beads" on the string represents a different amino acid, so while the gross stucture looks similar, at the fine level they are very different, especially in the binding region(s).

Reading about naltrexone is a good idea.

[Maine_Nurse]

6. There is a lot that is unknown...

You can't simply do research on something that requires opening up a living person's brain. A lot of research is animal or fish based or done with cadavers, none of which is really sure to translate directly to a living human's processes.

As I understand it, there are quite a variety of mechanisms that may be in play. Some molecules will bind to a certain receptor, blocking it from use by the real targeted molecule. In other cases, a chemical may reduce or increase the affinity of the receptor itself. Still another variation is to prevent/reduce the release of a targeted molecule once it has bound to a receptor and other times an introduced chemical may prevent the reabsorption of that molecule once released from the receptor. I'm sure there are plenty more variations also. Chemical pathways and messengers are incredibly complex.

[Orsino]

13. I thought I did.

Then I thought, "Well, look what's telling me that."