Abstract

It is generally accepted that stress as "perceived" by the nervous system can have an effect on the immune system and an organism's ability to fight off infectious agents that may lead to disease and/or mortality. Previous studies from our laboratory have shown evidence for communication of the nervous and immune systems in the beluga, Delphinapterus leucas. This includes sympathetic innervation of immune cells in lymphoid organs, the presence of beta-adrenergic receptors on peripheral blood lymphocytes, and functional changes in lymphocyte proliferation in the presence of adrenergic agonists in vitro.

We investigated activation of the nervous and immune systems in a beluga that was exposed to various challenges such as: loud sound, transport, and introduction to a novel environment, including new social interactions. Measurements taken before, during, and after exposure include catecholamines levels (high performance liquid chromatography), cortisol and aldosterone levels (radioimmunoassay), quantification of lymphocyte subsets (flow cytometry), DNA damage assessment of white blood cells (comet assay), serum chemistries, complete blood cell counts, and hematological parameters. Results indicate little or no change in nervous system activation and immunological parameters after exposure to peak sound pressures up to 198 kPa (28.7 psi) which were sufficient to cause temporary threshold elevations in hearing thresholds. There were however, changes in neural-immune measurements observed during transport in the stretcher, and after introduction to a novel environment including changes observed after introduction to another male and female beluga. Weekly and monthly monitoring of neural-immune measurements and behavior showed an adaptation to the new environment. Future studies will investigate neural-immune measurements in other belugas kept under human care as well as wild belugas, including different ages and genders. The potential clinical use of beta- blockers and immunostimulants will be investigated to help prevent adverse effects and maintain optimal health.

Acknowledgments

This work was supported by a grant from the Office of Naval Research # N00014-00-1-0041. The authors wish to thank Lee Berk and Lily Tran (Loma Linda University), Jeff Stott (UC Davis), John Metos (ARUP laboratories), Scott Steinert and Rebecca Streib Montee (SSC, San Diego), and the veterinary, animal care and training staffs at SSC, San Diego and Sea World of San Diego.