Lack of neuroleptic-like activity of l-fenfluramine.

Rats were trained to differentiate between the dopaminergically mediated discriminative stimuli produced by intraperitoneal administration of 4.8 mg/kg cathine and its vehicle. Once trained, three doses of l-fenfluramine (1.0, 2.0 and 2.5 mg/kg) were administered to determine if this agent would produce cathine-appropriate discriminative performance. All doses of l-fenfluramine were observed to produce vehicle-like responding. The 2.0 mg/kg dose of l-fenfluramine as well as 3.0 mg/kg chlorpromazine were administered in separate experiments prior to either cathine or vehicle. Chlorpromazine attenuated cathine-lever responding after cathine administration but did not affect vehicle responding. In contrast, l-fenfluramine had no effect upon cathine discrimination. The results indicate that l-fenfluramine shares neither agonist nor antagonist activity in the dopamine-mediated discriminative performance produced by cathine.