Interleukin-2-induced antinociception in morphine-insensitive rats.
OBJECTIVE
To investigate interleukin-2-induced antinociception in morphine-insensitive rats.


METHODS
Paw withdrawal latencies (PWL) to noxious radiant heat were taken as the measurement of pain threshold.


RESULTS
Intraplantar injection of human recombinant interleukin-2 (1.5 x10(4) U) significantly increased PWL in normal rats. PWL was also markedly increased by IL-2 in 45-d-post-complete Freund's adjuvant (CFA)-treated rats, which have been proven morphine-insensitive. IL-2-induced antinociception in CFA-treated rats were significantly lower than that in normal rats. IL-2-induced antinociception was partially blocked by naloxone (1 mg/kg, ip) in normal rats but remained unchanged in CFA group.


CONCLUSIONS
IL-2-induced antinociception is partially mediated by mu-opioid receptors. Therapeutic applications of IL-2 may also be expanded to relieve morphine-insensitive pain.
Song
Ping
P
Institute of Neurobiology, Fudan University, Shanghai 200433, China.
Liu
Xin-Yuan
XY
Zhao
Zhi-Qi
ZQ
D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004361:Drug Tolerance; D005620:Freund's Adjuvant / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D009020:Morphine / Q000009:adverse effects*; D009270:Naloxone / Q000494:pharmacology*; D010146:Pain / Q000188:drug therapy; D017288:Pain Threshold / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology / Q000627:therapeutic use
D000700:Analgesics; D007376:Interleukin-2; D017450:Receptors, Opioid, mu; D011994:Recombinant Proteins; D009270:Naloxone; D009020:Morphine; D005620:Freund's Adjuvant