title: Met-enkephalin modulates stress-induced alterations of the immune response in mice.
abstract: Overnight restraint stress of mice decreased ConA-driven lymphocyte proliferation, plaque-forming cell response to sheep red blood cells (SRBC), and NK activity in the spleen, but the phagocytic activity was enhanced. Injection of methionine-enkephalin (MENK), 10 mg/kg, i.p., 30 min before restraint, abolished these changes (except for the NK activity) and attenuated the stress-induced elevation of glucocorticoids. However, MENK itself affected the immune responses like stress: It decreased NK activity and the PFC response and enhanced phagocytic activity. Contrary to results with stress, MENK had no effect on cell proliferation. The opioid-receptor antagonist naloxone given before restraint reversed the stress-induced enhancement of phagocytosis and the decrease of T-cell proliferation. Alterations of the immune responses induced by restraint stress seem to be mediated by at least two mechanisms: activation of the hypothalamus-pituitary-adrenal (HPA) axis and the secretion of opioid peptides. MENK injected before stress may interfere with either or both mechanisms. T or B lymphocytes seem to be affected by the activation of the HPA axis, and phagocytes by a direct opioid action, whereas NK cells seem to be under the influence of another control mechanism.
authors.affiliation: Department of Experimental Biology and Medicine, Rudjer Boskovic Institute, Zagreb, Croatia.
authors.forename: T
authors.initials: T
authors.lastname: Marotti
authors.forename: J
authors.initials: J
authors.lastname: Gabrilovac
authors.forename: S
authors.initials: S
authors.lastname: Rabatic
authors.forename: L
authors.initials: L
authors.lastname: Smejkal-Jagar
authors.forename: B
authors.initials: B
authors.lastname: Rocic
authors.forename: H
authors.initials: H
authors.lastname: Haberstock
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D003208:Concanavalin A / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D004912:Erythrocytes / Q000276:immunology; D006462:Hemolytic Plaque Technique; D007109:Immunity / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects; D012149:Restraint, Physical; D012756:Sheep / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000187:drug effects; D013315:Stress, Psychological / Q000276:immunology* / Q000503:physiopathology*
chemical_list: D009292:Narcotic Antagonists; D003208:Concanavalin A; D009270:Naloxone; D004744:Enkephalin, Methionine; D003345:Corticosterone