Dopamine antagonists produce an age‐dependent increase in the responding of the young chick

Abstract

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.

Dopamine D‐2 receptor mediation of response suppression learning of young rats

“…Additional work with DA antagonists indicates that the DA D-2 receptor system is critical for response suppression learning in the chick (Zolman & McDougall, 1986). Therefore, the purpose of the present experiment was to determine whether the specific D-2 agonist LY 171555 (0.005,0.01, and 0.1 mg/kg) would affect the age-dependent improvement in response suppression learning of preweanling rat pups.…”

“…At present, the cholinergic neurotransmitter system is generally considered the primary mediator of response suppression learning; however, DA involvement in the development of response suppression learning of young chicks has been shown, as the nonspecific DA agonist apomorphine disrupts the chicks' ability to inhibit responding on a punished appetitive key-peck task (McDougall et al, 1987). Additional work with DA antagonists indicates that the DA D-2 receptor system is critical for response suppression learning in the chick (Zolman & McDougall, 1986). Therefore, the purpose of the present experiment was to determine whether the specific D-2 agonist LY 171555 (0.005,0.01, and 0.1 mg/kg) would affect the age-dependent improvement in response suppression learning of preweanling rat pups.…”

“…In contrast, haloperidol has the opposite effect in 1-day-old chicks, as haloperidol-treated 1-day-olds respond on significantly more responsecontingent punishment trials than their saline-treated age-mates (Zolman & McDougall, 1986). This "paradoxical" increase in punished responding is most likely due to haloperidol's DA D-2 antagonist properties, since sulpiride (a specific DA D-2 antagonist) also enhances the punished key-peck responding of I-day-old chicks (Zolman & McDougall, 1986).…”

“…Haloperidol (a nonspecific DA receptor antagonist) completely attenuates this apomorphine-induced pecking, and 4-day-old chicks given haloperidol alone inhibit their punished responding even more quickly than saline-treated controls (McDougall, Zolman, & Mattingly, 1987). In contrast, haloperidol has the opposite effect in 1-day-old chicks, as haloperidol-treated 1-day-olds respond on significantly more responsecontingent punishment trials than their saline-treated age-mates (Zolman & McDougall, 1986). This "paradoxical" increase in punished responding is most likely due to haloperidol's DA D-2 antagonist properties, since sulpiride (a specific DA D-2 antagonist) also enhances the punished key-peck responding of I-day-old chicks (Zolman & McDougall, 1986).…”

Localization of dopamine D1 receptors and dopaminoceptive neurons in the chick forebrain

“…Biochemical investigations revealed changes of DA-stimulated cAMP-synthesis in relation to auditory imprinting (Reiser et al, 1995). The dopaminergic system is involved in a broad array of behavioral responses and in learning paradigms in birds such as stereotyped pecking (Cheng and Long, 1974;Brunelli et al, 1975;Zarrindast and Amin, 1992), yawning and sedation (Ferrari and Giuliani, 1993), passive avoidance training (Stewart et al, 1996), and response suppression learning (McDougall et al, 1987;Zolman and McDougall, 1990). Although there is increasing knowledge about the organization of the dopaminergic innervation of the avian forebrain Waldmann and Gü ntü rkü n, 1993;Moons et al, 1994;Reiner et al, 1994;Wynne and Gü ntü rkü n, 1995;Karle et al, 1996;Metzger et al, 1996), only little is known about the distribution (Richfield et al, 1987;Dietl and Palacios, 1988;Casto and Ball, 1994) and role (Schnabel and Braun, 1996;Stewart et al, 1996) of the different DA receptor families and the associated intracellular messenger systems.…”