CNO is used at 1mg/Kg or 3mg/Kg in rats for IP injections. I did not find any papers reporting the use of the agonist 21 on rats and the concentration used
I am sure you have already found your answer, however, perhaps someone else is asking the question and will read your topic. We have just added a preprint study on BiorXiv which reports specific but also aspecific effects with C21 at doses commonly used.