Dopamine antagonists produce an age-dependent increase in the responding of the young chick.
In three experiments the effects of dopamine receptor antagonists on response-contingent punishment and autoshape learning of 1- and 4-day-old chicks were determined. In the first two experiments, 1- or 4-day-old chicks (N = 120) were trained to key-peck for heat reward and then injected intraperitoneally (ip) with either haloperidol (1.5, 2.5, or 5.0 mg/kg) or saline (Experiment 1) and with either haloperidol (2.0 mg/kg), sulpiride (50 mg/kg) or saline (Experiment 2) 30 min before a 96-trial response-contingent punishment session. In Experiment 3, 1- and 4-day-old chicks (N = 48) were injected ip with saline or haloperidol (2.0 mg/kg) 30 min prior to a 30-trial autoshape learning session. In both the punishment and appetitive tasks 1-day-old chicks pretreated with either haloperidol (1.5 to 2.5 mg/kg) or sulpiride showed a significant increase in key-peck responding compared with their saline injected controls. In contrast, 4-day-old chicks given either haloperidol (2.0 mg/kg) or sulpiride did not differ significantly from saline treated chicks on the punishment task, and on the autoshape task haloperidol-treated 4-day-old chicks responded on fewer trials than did their saline controls. These results indicate that dopaminergic synaptic transmission in the young chick as measured by dopamine D2 receptor blockers is functionally different at 1 compared with 4 days of age.
Zolman
J F
JF
Department of Physiology and Biophysics, A.B. Chandler Medical Center, University of Kentucky, Lexington 40536-0084.
McDougall
S A
SA
D000367:Age Factors; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects*; D001143:Arousal / Q000187:drug effects*; D001362:Avoidance Learning / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D002645:Chickens; D003214:Conditioning, Classical / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006220:Haloperidol / Q000494:pharmacology; D011939:Mental Recall / Q000187:drug effects; D011954:Receptors, Dopamine / Q000187:drug effects*; D017448:Receptors, Dopamine D2; D013469:Sulpiride / Q000494:pharmacology
D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D013469:Sulpiride; D006220:Haloperidol