One-way generalization of clonidine to the discriminative stimulus produced by cocaine.
Rats were trained to discriminate the stimulus properties of either cocaine or clonidine using a food reinforced two-lever choice paradigm. After training, cocaine was generalized to the cocaine lever in a dose-dependent manner, and clonidine was generalized to the clonidine lever in a dose-dependent manner. Yohimbine, an alpha-2 antagonist, blocked the clonidine stimulus but not the cocaine stimulus. Cocaine was not generalized to the clonidine stimulus; however, clonidine was generalized to the cocaine stimulus, and this generalization was blocked by yohimbine. The one-way generalization of clonidine to cocaine suggests that clonidine has at least two discrete stimulus components: a major component that is not cocaine-like, and a minor component that can be detected by cocaine-trained subjects. In addition, the yohimbine blockade data suggest that both components of the clonidine stimulus are mediated via alpha-2 receptors.
D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D004192:Discrimination, Psychological / Q000187:drug effects*; D005795:Generalization, Stimulus / Q000187:drug effects*; D008297:Male; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D015016:Yohimbine / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D003042:Cocaine; D003000:Clonidine