title: Immunomodulating effects of morphine microinjected into periaqueductal gray.
abstract: OBJECTIVE
  To study the effects of morphine on immune system through rat brain periaqueductal gray (PAG).
  
  
  METHODS
  Three hours after microinjection of morphine through the implanted steel tubes to PAG, splenic cytokines interleukin 2 (IL-2), interleukin 6 (IL-6), tumor necrosis factor (TNF), and natural killer cells (NK) activity were measured.
  
  
  RESULTS
  Microinjection of morphine (0.5 microL, 3672 ng) into PAG region had no influence on IL-6 and TNF-alpha (production of splenic macrophages, suppressed the natural killer cell (NK) activity and enhanced T-lymphocyte functions, including concanavalin A (Con A)-induced T-cell proliferation, IL-2 and TNF-beta production. Both the suppressive and stimulating actions were blocked by PAG preinjection of the mu opioid receptor antagonist naloxone (0.5 microL, 1 microgram), which alone showed the contrary effect to morphine.
  
  
  CONCLUSIONS
  Morphine affected immunofunctions through opioid receptors in PAG, and the influences on various immunocompetent cells were different.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China.
authors.forename: T H
authors.initials: TH
authors.lastname: Bian
authors.forename: X Y
authors.initials: XY
authors.lastname: Li
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D005260:Female; D007376:Interleukin-2 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology; D008233:Lymphotoxin-alpha / Q000096:biosynthesis; D051379:Mice; D008813:Mice, Inbred ICR; D008845:Microinjections; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D015213:Neuroimmunomodulation; D010487:Periaqueductal Gray / Q000276:immunology*; D013601:T-Lymphocytes / Q000187:drug effects
chemical_list: D007376:Interleukin-2; D008233:Lymphotoxin-alpha; D009020:Morphine