Meeting Abstract

P3.196  Tuesday, Jan. 6  How might changes in corticosterone levels in breeding greater-sage grouse affect immunity? JANKOWSKI, Mark D*; FRANSON, J Christian; HOFMEISTER, Erik; Los Alamos National Laboratory mdjankowski@lanl.gov

Greater sage-grouse (GRSG, Centrocercus urophasianus) populations are thought to have decreased by up to 93% since pre-settlement times. Male GRSG participate in spring mating rituals that involve intraspecific competition and reduced feeding. We investigated whether cattle grazing could be a stressor by studying GRSG fecal corticosterone (CORT) concentrations in exposed and unexposed populations. We found that lekking females but not males had elevated levels of CORT when resident in actively grazed sites. Males uniformly showed higher CORT levels during lekking compared to the brood-rearing period. Next, we investigated if elevated CORT might be uniformly immunosuppressive. Therefore, we performed a laboratory study using the domestic chicken (Gallus domesticus) to determine whether subacute elevations of CORT cause immunosuppression to both non-replicating and replicating antigens. Compared to controls, birds exposed to 10 days of CORT in their drinking water produced lower antibody levels to sheep red blood cells but more antibodies to West Nile virus (WNv). We suspect that CORT suppressed the same immune factors to both antigens, but that suppressed innate immunity allowed WNv to quickly replicate, leading to a higher viremia and a greater stimulus for antibody production. The relationship between higher CORT levels and immunosuppression in birds behaving according to their life history stage and those experimentally manipulated for higher levels of CORT should be addressed. These findings may stimulate further work to investigate how life history stage affects the neuro-endocrine-immune triad in the context of environmental change and perhaps as this relates to wildlife and public health risk.