Centrally applied NPY mimics immunoactivation induced by non-analgesic doses of met-enkephalin.
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.
von Hörsten
S
S
Department of Functional and Applied Anatomy, Medical School of Hannover, Germany.
Nave
H
H
Ballof
J
J
Helfritz
F
F
Meyer
D
D
Schmidt
R E
RE
Stalp
M
M
Exton
N G
NG
Exton
M S
MS
Straub
R H
RH
Radulovic
J
J
Pabst
R
R
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
D000276:Adjuvants, Immunologic; D000700:Analgesics; D009478:Neuropeptide Y; D004744:Enkephalin, Methionine