It may be safer (for interpretation of your results), much more elegant and be easier to explain if you use a more controlled method of delivery. Probably the best would be implanting CNO-loaded Alzet osmotic minipumps.

Good luck.

It may be safer (for interpretation of your results), much more elegant and be easier to explain if you use a more controlled method of delivery. Probably the best would be implanting CNO-loaded Alzet osmotic minipumps.

Good luck.

Hi, I was wondering how did you finally solve this question Aric. Did you try activation of DREADDs with CNO in drinking water? or did you try an Alzet osmotic pump? So far I have only seen a paper referencing unpublished results regarding the CNO in drinking water, and in other papers they use IP injections every 2 hours. Which concentration of CNO per day are you targeting at? And which provider were you using for CNO?

Never tested it myself:

From: http://chemogenetic.blogspot.com/2014/03/cno-in-drinking-water.html

1. Dissolve the CNO in a small volume of DMSO

2. Diluted the dissolved CNO in drinking water (e.g., 5mg/200ml)

3. Give mice with CNO drinking water and protect from light using foil-wrapped bottles

4. The mice will receive 5mg/kg/day CNO (assume that mice weight 30g and consume 6ml water per day)

5. Prepare fresh daily.

6. A small amount of saccharine in the drinking water will mask the slightly bitter taste of CNO

CNO has been given by drinking water, we are currently doing that. Basically, water intake needs to be measured each day and the dose adjusted daily to accommodate any changes in water intake (which is likely to happen when dreadd is activated).

Our lab typically gives CNO as a systemic injection. We use Dreadds and CNO to examine effects on behavioral tasks, so typically a single systemic injection near the time of behavioral testing is enough to reveal Dreadd effects.

Some labs have reported that the effect of CNO IP injection lasts for around 2h, therefore some labs have used IP injections every 2 hours several times per day, but I think this might be inconvenient for long treatments. The main problem I have is which dose to use per day, that group were using 1mg/kg several times a day, so I don't know which dose should I target per day, additionally I'm using rats, but it seems that they use similar concentrations than in mice. I guess I will have to try different doses too. But if you have any reference it would help!

Not a reference from my lab, but Gary Aston-Jones' lab gave 3 different systemic doses of CNO 0.1, 1.0 and 10mg/kg 20min before a behavioral task and found behavioral effects at all three doses.

http://www.pnas.org/content/early/2014/02/19/1310025111.full.pdf

Mark Mayford's lab has a Science paper from a few years back giving systemic CNO in mice at 0.5mg/kg 28mins before behavior and shows behavioral effects. http://www.sciencemag.org/content/335/6075/1513.full

I have a related question. I noticed some papers referencing SQ instated of IP injections of CNO in rats. SQ seems so much easier (and less stressful) to do in rats but has anyone proven it actually works equally well as IP injections?

A related question. Has any of you experience in giving CNO to pups? will it passin the milk of the mother to the pups? Many thanks to anyone who would share this information.

FYI, we have given up to 20mg/kg i.p. to rats and not seen nonspecific behavioral effects of CNO (Mahler et al Nat Neurosci 2014). I believe the main effect of giving such high doses is to prolong the effects of CNO activity at DREADDs (10mg/kg and up in rats lasts 2hrs+, and i suspect significantly longer than that), though we have not characterized effects at >2.5hrs after injection of any dose.

Does anyone has recent data/personal experience on giving CNO (or directly clozapine) in drinking water?

And any feedbacks on the transmission through maternal milk ? What would be the dose to inject/put in water, in order to have DREADD effects in the pups?