Burstein S, Hunter S A, Latham V, Renzulli L
Experientia. 1987 Apr 15;43(4):402-3. doi: 10.1007/BF01940427.
The results described here demonstrate that THC-induced catalepsy in mice can be substantially inhibited by the prior administration of delta 1-THC-7-oic acid, the major metabolite of THC in most species including humans. This raises the possibility that the intensity and duration of action of THC may depend to a large degree on the levels of this metabolite at the sites of action.