Short-term fasting increases food seeking behaviour and hypothalamic neuropeptide Y mRNA in Japanese quail chicks

Little is known about the central mechanisms regulating the onset of appetite in birds in early life and here we investigated how changes in nutritional status and food availability effect the hypothalamic pathways modulating appetite in young Japanese quail (Coturnix japonica). Nine-day old chicks (both sexes; n=22-26/group/sex) kept on (19L:5D) were randomly assigned to FED (control, ad libitum feeding) or FASTED (4h fast from lights on, food removed at lights off) groups and food seeking behaviour and appetite-related hypothalamic gene expression was compared. FASTED chicks exhibited significantly lower body and gut weights as well as lower blood glucose levels and increased firing of hypothalamic feeding circuit neurones compared to FED controls. Behavioural analysis of video recordings and RFID PIT tagged chicks showed that FED and FASTED chicks rested and rarely fed or drank during darkness. Following lights on chicks immediately exhibited food-seeking behaviour and the feeding station was visited with increased frequency during the first 2h of lights on. FASTED chicks showed increased food seeking behaviour at the empty feeding station compared to the FED chicks. At 4h following lights on chicks were killed and RT-qPCR analysis of appetite-related hypothalamic gene expression, showed a significant increase in hypothalamic neuropeptide-Y (NPY), but not agouti-related peptide (AgRP), Proopiomelanocortin (POMC) or cocaine-and-amphetamine-regulated transcript (CART) mRNA in FASTED quail compared to the FED control chicks. Thus, negative energy balance caused by food restriction enhances food-seeking behaviour in male and female chicks, and this was associated with increased hypothalamic NPY mRNA expression.