Meeting Abstract
P3.126 Wednesday, Jan. 6 Species-specific habitat-associated changes in lipolytic metabolites during the avian stress response FOKIDIS, B*; SPARR, R; SWEAZEA, K; DEVICHE, P; Arizona St. Univ.; Arizona St. Univ.; Arizona St. Univ.; Arizona St. Univ. bfokidis@asu.edu
The vertebrate stress response is associated with glucose mobilization, a result of glycogen mobilization and subsequent gluconeogenesis partly via lipolysis. This idea is largely based on research in captive rodents and few data on the subject are available for free-ranging birds. Birds differ from mammals in having higher plasma glucose levels and varying lipid storage mechanisms, and many use fatty acids to power muscles during flight. Body condition (i.e., energy stores) may also affect reliance on lipids during stress. We measured acute stress-induced changes in plasma glucose, free glycerol, triglycerides, and the ketone B-OH-butyrate in two songbirds: Curve-billed Thrashers (CBTH) and House Sparrows (HOSP), sampled in urban, farm, and desert habitats that putatively differ in resource abundance. Urban and farm birds have more robust stress responses and are in better body condition, which may increase substrates for gluconeogenesis, than desert birds. We predicted urban and farm birds to show greater reliance on lypolysis during stress, as evidenced by decreased triglycerides, free glycerol, and increased ketone production, than desert birds. This prediction was partly supported for desert CBTH, which depleted plasma triglycerides and free glycerol more than urban birds during stress. Stress was, however, associated with lower plasma ketones in desert than urban CBTH. Farm HOSP with unlimited food access also had higher plasma ketones during stress than urban birds, but urban HOSP had lower plasma triglycerides than farm birds. Stress did not affect plasma glucose but decreased triglycerides in HOSP from both habitats. The data support the hypothesis that lipolysis is a major response to acute stress and this response varies as a function of habitat and body condition.
