Meeting Abstract

12.9  Monday, Jan. 4  Immune function in mice selected for high metabolic rate DOWNS, C.J.*; WONE, B.; DONOVAN, E.R.; HUNTER, K; HAYES, J.P.; Univ. of Nevada, Reno; Univ. of Nevada, Reno; Univ. of Nevada, Reno; Univ. of California, Riverside; Univ. of Nevada, Reno; Univ. of Nevada, Reno downsc@unr.nevada.edu

Life history theory posits that trade-offs exist among energetically expensive activities. Mounting an immune response may be energetically expensive, so a trade-off may exist between metabolic rate and immune function. Indeed, we tested the hypothesis that basal metabolic rate (BMR) is negatively correlated with innate and adaptive immune function in laboratory mice (Mus musculus) selected for mass-independent metabolic rates. We artificially selected replicate lines of mice high maximal metabolic rate (MAX), high maximal metabolic rate and low BMR (COR), and maintained replicated control lines (CONT). After 7 generations of selection, BMR of selected mice diverged significantly. MAX lines had BMR ~5% > the CONT lines and the COR lines had BMR ~5% < CONT lines. We tested the ability of mice to mount an innate immune response by injecting them with lipopolysaccharide (LPS), an endotoxin from Gram-negative bacteria. To test adaptive immune response, we inoculated a second group of mice with Keyhole Limpet Haemocyanic (KLH). After each immune treatment, we measured metabolic rate during the immune response and immune indicators in blood plasma. Mice treated with either LPS or KLH used more energy then control sham mice (injected with saline), however, there was no difference in energy used among mice from the selected treatments. This suggests that immune responses are expensive, but that the 5-10% differences in BMR among selection treatments were not great enough to alter the energetics of mounting an innate or adaptive immune response. Supported by NSF IOS 0344994.