title: Social confrontation "stress" in aggressive fish is associated with an endogenous opioid-mediated suppression of proliferative response to mitogens and nonspecific cytotoxicity.
abstract: 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.
authors.affiliation: Department of Anatomy, University of California, Los Angeles 90024.
authors.forename: M
authors.initials: M
authors.lastname: Faisal
authors.forename: F
authors.initials: F
authors.lastname: Chiappelli
authors.forename: I I
authors.initials: II
authors.lastname: Ahmed
authors.forename: E L
authors.initials: EL
authors.lastname: Cooper
authors.forename: H
authors.initials: H
authors.lastname: Weiner
mesh_terms: 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*
chemical_list: D004723:Endorphins