The title pretty much says it all. I've checked both Wiki and Google, so if someone says UTFSE, or finds a source within less than a minute of searching, I'll be pissed.

Well, what confuses me about this topic is that I was always fairly certain that dopamine causes dilation, for some reason or another. But opiates create a contradiction to this theory, as one's pupils remain constricted throughout the duration of an opiate high. Caffeine also comes to mind, as it releases dopamine, but does not affect the pupils in any manner (right?).

Oh, and LSD and most hallucinogens too. They bind primarily to serotonin receptors, and yet cause dilation far beyond that of any dopaminergic drug. So... what's up with that?

i think its the dopamine, and other factors that people who are neurologists dont know about.

ive often wondered the same thing about marijauna eye reddness

Expansion of dem bloodvessels. For the eye redness thing.

Depends on the drug.

Anticholinergics, as their name suggets, blocks the action of ACh, which is used by the PNS. Pupil constriction is controlled by the PNS, so when the PNS's neurotransmitter is unavailable, well, hello Mr. Mydriasis.

Dopamine tends to cause mydriasis through adrenergic receptor agonism. Excite the adrenergic receptors > increase adrenaline release > pupils dilate.

Opiates don't disprove this, it just shows that whatever is causing the miosis is moar powerful than dopamine's mydriatic action. In this case, opioids cause miosis through the K-OR. What exactly the K-OR has to do with miosis, you've got me, but that appears to be the rub...

As for serotonergic hallucinogens and pupil dilation... Mydriasis is a common symptom in serotonin syndrome, and 5-HT3 acts on the PNS, so it's reasonable to assume, I would imagine, that drugs that bind to 5-HT3 at least (possibly other receptors, as well) might cause mydriasis through that pathway. Whether or not LSD or any other bind to 5-HT3, I have no idea :D Sorry.

Ahh fuck, so many drug-related terms I don't know anything about!

It's like I'm seeing colors I've never seen before!

http://www.merriam-webster.com/

.peace.

Ahh fuck, so many drug-related terms I don't know anything about!

It's like I'm seeing colors I've never seen before! Sorry. Hope this clears it up:

Anticholinergics - Drugs that block the action of acetylcholine, like benadryl, datura, etc.
ACh - Acetylcholine; a neurotransmitter
PNS - Either peripheral nervous system or, in this case, parasympathetic nervous system. I guess PSNS would be more appropriate, but the parasympathetic is part of the peripheral anyway, so it's not that big of a deal
Mydriasis - Pupil dilation
Miosis - Pupil constriction
K-OR - Kappa opioid receptor
5-HT3 - A family of 5-HT (serotonin) receptors

robinhoody your too sweet

moar than I am anyways... :p

.peace.

Sorry. Hope this clears it up:

Anticholinergics - Drugs that block the action of acetylcholine, like benadryl, datura, etc.
ACh - Acetylcholine; a neurotransmitter
PNS - Either peripheral nervous system or, in this case, parasympathetic nervous system. I guess PSNS would be more appropriate, but the parasympathetic is part of the peripheral anyway, so it's not that big of a deal
Mydriasis - Pupil dilation
Miosis - Pupil constriction
K-OR - Kappa opioid receptor
5-HT3 - A family of 5-HT (serotonin) receptors

Haha, thanks, but I already knew what ACh, PNS, and mydriasis/miosis meant. :p

Still, thank you; this does answer most of my question quite nicely!

Ok I have a question that may or may not be really stupid.

If one were to obtain Mydriatic eye drops or Miotic eye drops would they counter-act the dilation/constriction caused by drug use and would this have any effect on the drug that is causing dilation/constriction?

The point of doing this could obviously be to reduce one of the common signs of drug use and with this usage you would need to not only have a counter-action to the drug's effect on the pupils but also the correct dose to "not go to far" and cause a sign of use of another drug.

Is this use of the eye-drops a possibility?
I'm not asking if it is in terms of "If I put drops in my eye will it make me look less like I'm on E?" but more of a "Is it possible and therefore something that after lots of research/experimentation could potentially be used for the purpose of reducing one sign of drug use?". I add this only to note that this question is based out of curiosity, not the intention to go and get some eyedrops/use em and expect results.

Ya it's possible.

You can do all the bitchwork of finding which drops are best for which drugs.

Though there's not much point, seein as the pupil dilates and constricts according to the amount of light the your retina can handle. :)

I love when robin posts here, I always learn shit. We missed you man.........

Seriously.

you should post moar often

great answers, i learned something

Robin 4 president


pedo for chancellor

I haven't read any of this thread but it seems like there's a lot of complicated, crazy shit that people are posting. Well pupil dilation is done by the sympathetic nervous system, while pupil constriction is done by the parasympathetic nervous system. All it depends on is which neurotransmitters the chemical you are taking acts on, and subsequently which organs it affects.

troll. GTFO.

I feel accomplished after reading this thread.

ROFL!


QFMFT. :D

I know someone who got shot in the eye with a BB gun and the doctors gave him this eyedrop which made his pupil dialate.

Anyone know what they are?

Some kind of Mydriatic eye drops.

But why do the blood vessels expand?