Inhibition of nociceptive withdrawal reflex by microinjection of interleukin 2 into rat locus coeruleus.
This study was to examine the effects of microinjection of human recombinant interleukin 2 (IL-2) into locus coeruleus (LC) on spinal nociception. Following application of IL-2 (0.1 microl, 10 pM) into LC, the percentage of inhibition of nociceptive C responses of reflex at 3, 9, 15, 21 and 27 min after injection were 88.2 +/-9.4%, 84.0 +/- 11.8%, 89.7 +/- 10.5%, 57.1 +/- 8.7% and 26.3 +/- 12.2%, respectively. Also, the expression of Fos protein in superficial dorsal horn was reduced by 73.01 +/- 13.58% of control (P<0.0001). Naloxone (10 microg, i.p.) completely blocked the IL-2-induced inhibition of C responses. The results clearly show that IL-2 receptors present in LC mediate descending inhibition of the spinal nociception, which may couple with the activation of opioid receptors on LC neurons.
Guo
H
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Key Laboratory of Neurobiology, Shanghai Institute of Physiology, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
Zhao
Z Q
ZQ
D000818:Animals; D004558:Electric Stimulation; D007839:Functional Laterality; D016762:Genes, fos / Q000187:drug effects; D006801:Humans; D007376:Interleukin-2 / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008125:Locus Coeruleus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology*; D020671:Posterior Horn Cells / Q000187:drug effects / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
D007376:Interleukin-2; D016760:Proto-Oncogene Proteins c-fos; D011994:Recombinant Proteins; D009270:Naloxone