M. Nagae et al., THE EFFECT OF CORTISOL ADMINISTRATION ON BLOOD-PLASMA IMMUNOGLOBULIN-M (IGM) CONCENTRATIONS IN MASU SALMON (ONCORHYNCHUS-MASOU), Fish physiology and biochemistry, 13(1), 1994, pp. 41-48
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 p
lasma IgM concentrations was investigated using a specific antibody to
IgM in masu salmon (Oncorhynchus masou). Cortisol was orally administ
ered each day for 2 weeks at a dose of 1 mg g-1 in the diet, and for t
he following week the fish were fed a non-treated diet. Blood plasma s
amples were collected at 0, 1, 2 and 3 weeks after the initiation of t
reatment. Oral administration of cortisol elevated plasma cortisol con
centrations to about 40 ng/ml for 2 weeks after administration and sli
ghtly reduced plasma IgM concentration; the suppression was statistica
lly significant one week after the period of hormone administration. H
owever, treatment with cortisol did not affect plasma concentrations o
f total protein or alpha1-protein, one of the major serum proteins, du
ring the experimental period. These results indicate that cortisol spe
cifically suppresses plasma IgM concentrations.