Hello,

This is a pretty hard question to answer when discussing cannabinoids. When you're reffering to Emax, which particular effect of WIN55,212-2 are you referring to? Because cannabinoids can have many different effects (many of which are going to be incredibly hard to measure in rodents, as more of them are psychological than are physiological). So could you give me a bit more context - do you have a specific response that you are interested in?

Cheers

Hi Javed, thanks for your reply.

I will be administering WIN to fear conditioned mice to determine its effects on the conditioned response during fear extinction trials.

I have 3 extinction trials over 2 days and am just determining whether 1 administration of the drug would essentially still be in the system over this whole time period, and whether further administrations after the 1st would be potentially unnecessary. 

https://www.researchgate.net/post/Does_any_one_know_the_WIN55_212-2_half-life_in_rats pointed out that the wash out period is 24 - 36 hours. If this is the case I was thinking it might be best for me to just give the one application at the first extinction session.

Another researcher in the lab told me to determine the Emax of the drug, thats why I thought I'd post here. 

Sorry if that is confusing! 

Hey Kristie,

Sorry for the delay, I've been really busy (and exhausted)! Sounds like an interesting experiment. May I ask why you chose WIN55,212-2 for this, rather than a simpler cannabinoid like THC? There's not much pharmacology data available for WIN55,212-2 at all.

Regarding whether you should give it more than once, I'd say that yes, you should give it again on the second day. Even though it has a ~ 24 hour half life, it's effects will be significantly reduced on the second day compared to the first. But whether you should give the same dose as the first day on the second day is much harder to answer - if you could measure the plasma levels of the drug over the two days, that would be helpful in determining the dose for the second day. Otherwise, I'd say just give the same dose as the first day.

Also, out of curiosity, how long after the first trial is the second one? Just wondering about how much of the drug will still be in the rodent's system at that time. I should also mention that the plasma concentration doesn't always correlate with the psychological effects of the drug, e.g sometimes the effects persist for a number of hours after all of the drug has left the system, but sometimes the effects are shorter lived than the half-life. I'd say dosing it on both days is the safest, but that's just my opinion.

Cheers,

Javed.