[Discriminative stimulus properties of ephedra herb (Ephedra sinica) in rats]

The stimulus properties of ephedra herb (drug of Chinese medicine) were demonstrated in rats trained to discriminate between 2.5 ml/kg extract of ephedra herb and same volume of distilled water (p.o.). On the discrimination training, animals were shaped on an FR20 schedule to respond to one of two levers for food reinforcement when they were administrated ephedra herb extract, and to respond to the other lever when they were treated with distilled water. Cumulative dosing tests for the discriminative stimulus properties consisted of two to five trials of FR20 schedule; responses for both levers were reinforced. d-Methamphetamine 1.43 mg/kg p.o. indicated complete generalization to the ephedra herb. Nicotine and caffeine indicated modest generalization, but some animals generalized completely. These results suggest that the ephedra herb has d-methamphetamine-like, but unique discriminative stimulus properties.