Central neuropeptide Y differentially regulates body temperature between heat-exposed and non-heat-exposed chicks

Heat stress due to exposure to high environmental temperatures influences thermoregulation and metabolic balance in poultry, and central neuropeptidergic pathways play a critical role in these responses. Central administration of neuropeptide Y (NPY) induces hypothermia under thermoneutral conditions (CT) in chicks but its thermoregulatory role during high environmental temperatures remains unclear. In the present study, male chicks were intracerebroventricularly injected with 1 nmol NPY, followed by exposure to CT (30 ± 1 °C), moderate ambient temperature (MT: 35 ± 1 °C) or high ambient temperature (HT: 40 ± 1 °C) for 2 h. We confirmed the hypothermic effect of central NPY under CT. Interestingly, central NPY induced hyperthermia under HT, but not MT. Central injection of NPY reduced plasma glucose concentration during CT and HT. Additionally, diencephalic dopamine concentrations increased under both CT and HT following central injection of NPY, while norepinephrine to 3-methoxy-4-hydroxyphenylglycol turnover decreased. In conclusion, the shift from a hypothermic role under CT to hyperthermic action under HT of NPY, combined with dopaminergic and metabolic modulations, suggest catecholamine metabolism may be involved with the differential thermoregulatory role of NPY.