Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2003
Publication Date: March 20, 2003
Citation: McMurtry, J.P., Brocht, D.M., Ashwell, C., Allen, P., Leach, R., Coon, C. 2003. The development of a homologous radioimmunoassay for chicken leptin [abstract]. Poultry Science. v. 82(Suppl. 1):85.
Leptin is involved in appetite and energy balance regulation, reproduction, and immune function in mammals. Whether leptin has similar roles in birds is largely unknown. To facilitate studies to delineate leptin's function in domestic fowl, an homologous double antibody RIA for chicken leptin has been developed. Recombinantly-derived chicken leptin (rcL) was used as antigen, radiolabeled tracer, and standard. The resulting RIA has a minimum detection limit of 0.15 ng and effective dose of 1.25 ng. Dose response curves of chicken and turkey plasma were parallel with rcL. The antiserum exhibits a cross-reactivity of 0.25 and 2.0 percent with human and mouse leptin, respectively. A series of experiments were conducted in chickens to evaluate changes in circulating leptin in which alterations in blood levels would be anticipated. A significant decrease in blood leptin was noted following 8 hrs of fasting, and levels returned to pre-fasting levels within 2 hrs of refeeding. Coccidial infections elicit changes in food intake. At 4 days post E. acervulina plasma leptin were significantly depressed compared to control chicks, and returned to pre-infection levels at approximately 11 days post infection. Broiler breeder hens reared on a feed restriction regime exhibited significantly lower blood leptin concentrations compared to breeders fed ad libitum. Chicks reared on a zinc deficient diet displayed elevated plasma leptin compared to birds fed a control diet and a pair-fed group. Circulating leptin concentrations were found to be greater in chicks exposed to an elevated ambient temperature (37 C) compared to chicks maintained at 22 C. Chicks reared on a phosphorus-deficient diet had elevated leptin levels in conjunction with elevated corticosterone concentrations. It is evident from these studies that leptin secretion is affected by many factors, including nutritional and health status, as well as environmental temperature.
Key Words: hormone, appetite, energy balance