title: The effect of cortisol administration on blood plasma immunoglobulin M (IgM) concentrations in masu salmon (Oncorhynchus masou).
abstract: Immunoglobulin M (IgM) is known as a main factor in the humoral immune system of teleosts. In the present study, the effect of cortisol on plasma IgM concentrations was investigated using a specific antibody to IgM in masu salmon (Oncorhynchus masou). Cortisol was orally administered each day for 2 weeks at a dose of 1 mg g(-1) in the diet, and for the following week the fish were fed a non-treated diet. Blood plasma samples were collected at 0, 1, 2 and 3 weeks after the initiation of treatment. Oral administration of cortisol elevated plasma cortisol concentrations to about 40 ng/ml for 2 weeks after administration and slightly reduced plasma IgM concentration; the suppression was statistically significant one week after the period of hormone administration. However, treatment with cortisol did not affect plasma concentrations of total protein or α1-protein, one of the major serum proteins, during the experimental period. These results indicate that cortisol specifically suppresses plasma IgM concentrations.
authors.affiliation: Department of Biology, Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido, 041, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nagae
authors.forename: H
authors.initials: H
authors.lastname: Fuda
authors.forename: K
authors.initials: K
authors.lastname: Ura
authors.forename: H
authors.initials: H
authors.lastname: Kawamura
authors.forename: S
authors.initials: S
authors.lastname: Adachi
authors.forename: A
authors.initials: A
authors.lastname: Hara
authors.forename: K
authors.initials: K
authors.lastname: Yamauchi