Stepping back from the big picture, how is one to determine where the signal resides, and what is noise in the system? One good approach is to explore results suggested in null mutant studies with further investigations using drugs and other research tools. For example, several different lines of mice engineered to lack the CB1 receptor gene showed reduced alcohol preference, and null mutants for the FAAH gene that had increased endogenous cannabinoids showed elevated preference. The potential role of the cannabinoid system was also supported by studies with CB1 receptor antagonist drugs, and studies with AA and ANA selected rat lines. The cannabinoid antagonist rimonibant is currently under investigation as a potential therapeutic agent for alcohol dependence (Crabbe et al. 2006).
