Phenytoin: similarity to tricyclic antidepressants.
Rats were trained to discriminate between the stimulus properties of intraperitoneal injections of 10 mg/kg phenytoin and its pH-adjusted vehicle in a two-lever, food-motivated operant task. Once trained, rats showed a dose-related decrease in discriminative performance with lower phenytoin doses. Administration of pentobarbital and chlordiazepoxide produced vehicle-appropriate responding, whereas injection of imipramine and amitriptyline produced intermediate results. Desipramine, at an intraperitoneal dose of 10 mg/kg, produced a pattern of responding similar to that observed after the training dose of phenytoin. These results demonstrate, for the first time, the ability of a non-disruptive dose of phenytoin to act as a behavioral discriminative stimulus in the rat and suggest the possibility of a common interoceptive cue property with tricyclic antidepressants.
D000639:Amitriptyline / Q000494:pharmacology; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology*; D002707:Chlordiazepoxide / Q000494:pharmacology; D003216:Conditioning, Operant; D003463:Cues; D003891:Desipramine / Q000494:pharmacology; D004193:Discrimination Learning; D007099:Imipramine / Q000494:pharmacology; D008297:Male; D010424:Pentobarbital / Q000494:pharmacology; D010672:Phenytoin / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D000929:Antidepressive Agents, Tricyclic; D000639:Amitriptyline; D010672:Phenytoin; D002707:Chlordiazepoxide; D010424:Pentobarbital; D007099:Imipramine; D003891:Desipramine