Central effects of the serotoninergic, GABAergic, and cholecystokinin systems on neuropeptide VF (NPVF)-induced hypophagia and feeding behavior in neonatal broiler chicken

Abstract

The study was performed to evaluate the role of central serotoninergic, GABAergic, and cholecystokinin systems in neuropeptide VF (NPVF)-induced hypophagia in broiler chickens. In this study, 9 experiments were designed, each with one control and three treatment groups (n = 44 in each experiment). Control chicks of all groups were subjected to normal saline + Evans blue 0.1 % Intracerebroventricular (ICV) injection. In the first experiment, 3 groups of chicks received NPVF (4, 8, and 16 nmol). In experiment 2–9, one group of chicks received NPVF (16 nmol), another received 10 µg fluoxetine (serotonin reuptake inhibitor) (experiment 2), 1.25 µg PCPA (serotonin synthesis inhibitor) (experiment 3), 1.5 µg SB-242,084 (5-HT2C receptor antagonist) (experiment 4), 15.25 nmol 8-OH-DPAT (5-HT1A receptor antagonist) (experiment 5), 0.5 µg picrotoxin (GABAA receptor antagonist) (experiment 6), 20 ng CGP54626 (GABAB receptor antagonist) (experiment 7), 1 nmol devazepide (CCKA receptor antagonist) (experiment 8), and 1 nmol/L−365(−|-),260 (CCKB receptor antagonist) (experiment 9), and another final group received combination of specific neurotransmitter + NPVF Then, the cumulative food intake was measured until 120 min post-injection. ICV injection of NPVF (8 and 16 nmol) significantly decreased food intake (P < 0.05). Simultaneous injection of fluoxetine + NPVF and also picrotoxin + NPVF significantly increased hypophagia caused by NPVF (P < 0.05). However, co-administration of PCPA + NPVF and also SB242084 + NPVF significantly decreased NPVF-induced hypophagia (P < 0.05). Finally, 8-OH-DPAT, CGP54626, devazepide, and L-365,260 had no effect on the hypophagia brought on by NPVF (P > 0.05). Count-type behaviors were dose-dependent and decreased in groups that received NPVF compared to the control group (P < 0.05). Our finding recommended an interconnection between central NPVF and serotoninergic, GABAergic, and cholecystokinin systems in neonatal chickens.