Synergistic effects of central nitrergic and glutamatergic systems on food intake in neonatal chickens

Food intake is a set of physiological mechanisms that affects different area of central nervous system. Glutamate has important role in central control of food intake in birds. On the other hand, nitric oxide (NO) is a hypophagic agent in birds. ‎The present study aimed to investigate the synergistic effects of glutamate and nitrergic system on feeding behavior in neonatal chickens. A total of one hundred- forty-four neonatal female laying hens (Hy-line) were randomly divided into three experimental groups. Each experiment had a control group and three treatment groups (n=12 in each group). In all experiments, 3-hour food-deprived (FD3) birds received intracerebroventricular (ICV) ‎injections either control diluent or drug solution. Then the birds had ad libitum access to the ‎food and fresh water, and then cumulative food intake (gr) was measured based on the ‎percentage of the body. In the first experiment, L-arginine (NO precursor, 200, 400 and 800 nmol) and in the second experiment, glutamate (75, 150 and 300 nmol) were ICV injected. In the third experiment, L-arginine (200 nmol), glutamate (75 nmol) and L-arginine + glutamate was injected. ‎ The results showed, ICV injection of L- arginine dose- dependently decreased food intake (P<0.05). Also, injection of the glutamate decreased food intake in a dose- dependent manner (P<0.05). Co-injection of sub-effective doses of L-arginine and glutamate significantly decreased food intake in neonatal chicks (P<0.05). According to the results, there is probably a synergistic effect between nitrergic and glutamatergic systems on food intake control of neonatal chicks.