The interplay of oxytocin and dopaminergic system: Effects on food consumption in broiler chickens

Oxytocin play a crucial physiological role in regulating feed consumption and maintaining energy homeostasis. Numerous studies have highlighted the influence of central dopaminergic systems on appetite control; however, there is a lack of information regarding their interaction with food intake regulation in avian species. Consequently, the present study aimed to investigate the potential interplay between the central oxytocin and dopaminergic systems in modulating food consumption in broiler chicks. In the initial experiment, various doses of oxytocin (2.5, 5, and 10 µg) and saline were administered via intracerebroventricular (ICV) injection to ascertain the effective dosage of oxytocin. The second experiment involved ICV injections of saline, SCH23390 (a D1 receptor antagonist), the identified effective dose of oxytocin, and a co-injection of SCH23390 with oxytocin. Subsequent experiments (3 to 7) followed a similar methodology, substituting SCH23390 with AMI-193 (a D2 receptor antagonist), NGB2904 (a D3 receptor antagonist), l-741,742 (a D4 receptor antagonist), 6-hydroxydopamine (a dopaminergic neurotoxin), and l-DOPA (a dopamine precursor), respectively. Cumulative food intake was measured over a period of 120 min post-injection. The findings revealed that ICV administration of oxytocin significantly reduced feed consumption in broilers compared to the control group (P < 0.05). Additionally, the co-infusion of SCH23390 and 6-hydroxydopamine alongside oxytocin significantly mitigated the hypophagic effect induced by oxytocin (P < 0.05). In contrast, AMI-193, NGB2904, l-741,742, and l-DOPA did not exhibit any significant influence on oxytocin-induced hypophagia (P ≥ 0.05). These findings suggest that the anorexigenic effect of oxytocin may be primarily mediated through D1 dopaminergic receptors in broilers.