title: Augmenting effect of opioid peptides on murine macrophage activation.
abstract: We investigated the effect of several opioid peptides on the activation of murine peritoneal exudate macrophages (M phi) in vitro. M phi were treated with interferon (IFN) as a priming agent and bacterial lipopolysaccharide (LPS) as a triggering agent in the presence or absence of opioid peptides. M phi activation was assessed by their tumoricidal activity. When treatment with IFN and LPS resulted in a high level activation of M phi, dynorphin-A exerted no further enhancing effect. When treatment induced only weak activation, however, dynorphin-A augmented the M phi activation. Leucine-enkephalin, methionine-enkephalin, and also beta-endorphin had augmenting effects. An opioid receptor antagonist, naloxone, reduced the effect of dynorphin-A and beta-endorphin. When M phi were treated sequentially with IFN and LPS, beta-endorphin operated in combination with LPS only. Moreover, beta-endorphin was effective for already activated M phi. These results indicate that opioid peptides act on M phi via classical opioid receptors, and that responsiveness to opioid peptides is induced in the triggering stage of M phi activation.
authors.affiliation: Department of Zoology, Faculty of Sciences, Kyoto University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hagi
authors.forename: K
authors.initials: K
authors.lastname: Uno
authors.forename: K
authors.initials: K
authors.lastname: Inaba
authors.forename: S
authors.initials: S
authors.lastname: Muramatsu
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004399:Dynorphins / Q000494:pharmacology; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology; D005260:Female; D008262:Macrophage Activation / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009270:Naloxone / Q000494:pharmacology; D001615:beta-Endorphin / Q000494:pharmacology
chemical_list: D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone; D001615:beta-Endorphin; D004399:Dynorphins