Discriminative stimulus properties of MDA analogs.

Rats trained to discriminate (+/-) 2,5-dimethoxy-4-methylphenylisopropylamine (DOM) (1.0 mg/kg) from saline, using a standard two-lever operant task, were challenged with various doses of 3,4-methylenedioxyphenylisopropylamine (MDA) and several related agents. The (+/-)-DOM stimulus generalized to (+/-)-MDA, suggesting that both agents apparently produce similar stimulus cues. Related agents, known to produce effects in man similar to those produced by (+/-)-MDA, also resulted in generalization when administered to the DOM-trained animals, e.g., R(-)-MDA and a methoxylated derivative of (+/-)-MDA, (+/-)-2-OMe-4,5-MDA. DOM stimulus generalization was not observed for S(+)-MDA, the N-monomethyl and alpha-demethyl derivatives of MDA, nor for a metabolite of MDA (i.e., 3-methoxy-4-hydroxyphenylisopropylamine). The results suggest that R(-)- and (+/-)-MDA, as well as (+/-)-2-OMe-4,5-MDA, but not the other derivatives of MDA, are capable of producing behavioral (stimulus) effects common to those produced by the training dose of (+/-)-DOM.