The effects of d-lysergic acid diethylamide (LSD), 2,5-dimethoxy-4-methylamphetamine (DOM) and d-amphetamine on operant responding in control and 6-hydroxydopamine-treated rats.
The purpose of the present study was to determine the role of central catecholaminergic neuronal systems in the effects of LSD, DOM and d-amphetamine on fixed ratio (FR) operant responding in rats. Food-deprived male rats were trained to press a bar for food reinforcement on a FR-40 schedule. Control responding on this schedule is characterized by a rapid, constant rate of responding (approximately 100 responses/min) throughout a 40 min test session. LSD and DOM, as with other hallucinogens, produced dose-dependent periods of nonresponding or "pausing," followed by reinstatement of responding at or near the control rate. Administration of the non-hallucinogen, d-amphetamine, did not produce "pausing," but caused the response rate to slow and become erratic. In animals pretreated intraventricularly with 6-hydroxydopamine (6-OHDA; 200 micrograms/10 microliter X 2), the response to LSD and DOM was unchanged, while the response to d-amphetamine was significantly diminished. The neurotoxin significantly decreased brain catecholamines to less than 25 percent of control in al regions examined, without altering 5-HT concentrations in these same regions. These data demonstrate that the effects of LSD and DOM on FR-40 responding are quite different from those of d-amphetamine, and that this difference may be due to the extent of catecholamine involvement in the effects of these agents.
D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine / Q000494:pharmacology*; D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects*; D003913:Dextroamphetamine / Q000494:pharmacology*; D006892:Hydroxydopamines / Q000494:pharmacology*; D008238:Lysergic Acid Diethylamide / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011930:Reaction Time / Q000187:drug effects
D000662:Amphetamines; D006892:Hydroxydopamines; D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine; D008238:Lysergic Acid Diethylamide; D003913:Dextroamphetamine