title: Centrally applied NPY mimics immunoactivation induced by non-analgesic doses of met-enkephalin.
abstract: Neuropeptide Y (NPY) and endogenous opioids (EOPs) such as methionine-enkephalin (Met-enk) regulate similar physiological responses, but it is not known whether nociceptive and immune responses also show analogy after intracerebroventricular (i.c.v.) application. Dose-response studies show that Met-enk stimulates the blood granulocyte and splenic natural killer (NK) cell function of Lewis rats at a low dose (10(2) ng/kg, i.c.v.), whereas a high dose (10(5) ng/kg) causes suppression of innate immune functions associated with analgesia in the hot-plate test. At 15 min, 1 h and 24 h after i.c.v. application, both Met-enk (10(2) ng/kg) and NPY (1 ng/kg) produced similar effects: An initial suppression of innate immune function was followed by a long lasting stimulatory action on cell functions and serum interleukin-6 (sIL-6) levels. Thus, central NPY application resembles Met-enk-induced immunostimulation at doses not affecting nociception, suggesting an involvement of both peptides in shaping stress-induced immunomodulation of the non-analgetic form, possibly via activation of a common immunomodulatory effector mechanism.
authors.affiliation: Department of Functional and Applied Anatomy, Medical School of Hannover, Germany.
authors.forename: S
authors.initials: S
authors.lastname: von Hörsten
authors.forename: H
authors.initials: H
authors.lastname: Nave
authors.forename: J
authors.initials: J
authors.lastname: Ballof
authors.forename: F
authors.initials: F
authors.lastname: Helfritz
authors.forename: D
authors.initials: D
authors.lastname: Meyer
authors.forename: R E
authors.initials: RE
authors.lastname: Schmidt
authors.forename: M
authors.initials: M
authors.lastname: Stalp
authors.forename: N G
authors.initials: NG
authors.lastname: Exton
authors.forename: M S
authors.initials: MS
authors.lastname: Exton
authors.forename: R H
authors.initials: RH
authors.lastname: Straub
authors.forename: J
authors.initials: J
authors.lastname: Radulovic
authors.forename: R
authors.initials: R
authors.lastname: Pabst
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D009478:Neuropeptide Y / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D000276:Adjuvants, Immunologic; D000700:Analgesics; D009478:Neuropeptide Y; D004744:Enkephalin, Methionine