Involvement of dopaminergic system in the nucleus accumbens in the discriminative stimulus effects of phencyclidine.
The effects of microinjection of phencyclidine (PCP) and dizocilpine, non-competitive NMDA receptor antagonists, and dopamine into the nucleus accumbens were examined in rats trained to discriminate PCP (1.5 mg/kg i.p.) from saline under a two-lever fixed ratio 20 schedule of food reinforcement. Microinjection of PCP (2-40 microg) and dizocilpine (2-12 microg) into the bilateral nucleus accumbens produced a dose-dependent increase in PCP-appropriate responding and fully substituted for systemically administered PCP, whereas microinjection of dopamine (1-4 microg) did not produce PCP-like discriminative stimulus effects. The performance of PCP discrimination was assessed after bilateral destruction of the dopaminergic nerve neurons in the nucleus accumbens with dopaminergic neurotoxin, 6-hydroxydopamine (6-OHDA, 4 microg/1 microl/side). The destruction of dopaminergic nerve neurons in the nucleus accumbens failed to prevent the performance of PCP discrimination. There was no difference in the average percentages of PCP-appropriate responding between vehicle and 6-OHDA-treated rats in the dose-response tests. These results suggest that the dopaminergic system in the nucleus accumbens does not play a critical role in the discriminative stimulus effects of PCP.
Mori
Akitomo
A
Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan.
Noda
Yukihiro
Y
Nagai
Taku
T
Mamiya
Takayoshi
T
Furukawa
Hiroshi
H
Nabeshima
Toshitaka
T
D018663:Adrenergic Agents; D000818:Animals; D004193:Discrimination Learning / Q000187:drug effects* / Q000502:physiology; D004298:Dopamine / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000502:physiology; D016627:Oxidopamine; D010622:Phencyclidine / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology
D018663:Adrenergic Agents; D018691:Excitatory Amino Acid Antagonists; D016627:Oxidopamine; D010622:Phencyclidine; D004298:Dopamine