Social confrontation "stress" in aggressive fish is associated with an endogenous opioid-mediated suppression of proliferative response to mitogens and nonspecific cytotoxicity.
We have previously shown that social confrontation between aggressive fish (e.g., Tilapia) produces a suppression of several immunological parameters--nonspecific cytotoxicity and mitogen-stimulated proliferation in pronephric leukocytes--in the subordinate fish. By using the opioid antagonist, naltrexone, we now demonstrate indirectly that this immunosuppression is in part mediated by the endogenous opioid system. Evidence is presented that naltrexone-mediated reversal of immunosuppression may be limited to the populations of the cytotoxic and T-cell lineages. The proliferation response to lipopolysaccharide is unaffected by naltrexone. Our data also demonstrate that serum from subordinate (immunosuppressed) fish is immunosuppressive in normal fish--an effect that can be reversed by naltrexone. These results support a link between the neuroendocrine and immune systems in fish, the lowest vertebrate.
Faisal
M
M
Department of Anatomy, University of California, Los Angeles 90024.
Chiappelli
F
F
Ahmed
I I
II
Cooper
E L
EL
Weiner
H
H
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004723:Endorphins / Q000378:metabolism / Q000502:physiology*; D005399:Fishes / Q000276:immunology* / Q000502:physiology; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology*; D013315:Stress, Psychological / Q000276:immunology*
D004723:Endorphins