Interconnection between adrenergic and dopaminergic systems on feeding behavior in neonatal chicks

Document Type: Original Articles

Authors

1 Department of Basic Science, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran

3 Department of Clinical Science, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran

Abstract

Central dopamine and adrenergic systems have prominent role on appetite regulation but their interaction(s) have not been studied in neonatal layer chicken. So, the aim of the current study was to determine interaction of the central dopaminergic and noradrenergic systems on food intake regulation in neonatal layer chicken. In experiment 1, chicken intracerebroventricular (ICV) injected with control solution, parazosin (α1 adrenergic receptor antagonist, 10nmol), dopamine (40nmol) and parazosin+dopamine. Experiments 2-5 were similar to experiment 1, except birds injected with yohimbine (α2 receptor antagonist, 13nmol), metoprolol (β1 adrenergic receptor antagonist, 24nmol), ICI 118,551 (β2 adrenergic receptor antagonist, 5nmol) and SR59230R (β3 adrenergic receptor antagonist, 20 nmol) instead of the parazosin. In experiment 6, chicken ICV injected with control solution and noradrenaline (NA; 75, 150 and 300 nmol). In experiment 7, birds injected with control solution, SCH23390 (D1 dopaminergic receptor antagonist, 5 nmol), NA (300nmol) and SCH23390+NE. In experiment 8, control solution, AMI-193 (D2 dopaminergic receptor antagonist, 5nmol), NA (300nmol) and AMI-193+ NA was injected. Then, cumulative food intake was recorded at 30, 60 and 120 min after injection. According to the results, ICV injection of the dopamine (40nmol) significantly decreased food intake in comparison to control group (p<0.05). Co-injection of the yohimbine plus dopamine significantly amplified dopamine-induced hypophagia in neonatal chicken (p<0.05). Also, co-administration of the ICI 118,551+dopamine significantly inhibited hypophagic effect of dopamine in neonatal chicken (p<0.05). Furthermore, noradrenaline (75, 150 and 300 nmol) significantly decreased food intake in a dose dependent manner (p<0.05). Co-injection of the SCH23390+NA decreased hypophagic effect of the NA in neonatal chicken compared to control group (p<0.05). Co-injection of the AMI-193+ NA diminished noradrenaline-induced hypophagia compared to control group (p<0.05). These results suggested an interconnection exists between central dopaminergic and noradrenergic systems through α2/β2 adrenergic and D1/D2 dopaminergic receptors on food intake regulation in neonatal chicks.

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