The opposing effects of interleukin -1 beta microinjected into the preoptic hypothalamus and the ventromedial hypothalamus on nociceptive behavior in rats.
The effects of microinjections of recombinant human interleukin-1 beta (rhIL-1 beta) into the hypothalamus and neighboring basal forebrain on nociceptive behavior were studied using a hot-plate test in rats. The microinjection of rhIL-1 beta at doses between 5 pg/kg and 50 pg/kg into the medial part of the preoptic area (MPO) reduced the paw-withdrawal latency. The maximal reduction was obtained 30 min after the injection of rhIL-1 beta at 20 pg/kg. RhIL-1 beta (20 pg/kg)-induced hyperalgesia was completely blocked by the simultaneous injection of IL-1 receptor antagonist (IL-1ra, 20 ng/kg), Na salicylate (200 ng/kg) or alpha-melanocyte-stimulating hormone alpha-MSH, 20 ng/kg). The intra-MPO injection of rhIL-1 beta at doses of less than 5 pg/kg or more than 50 pg/kg (up to 2 ng/kg) into the paraventricular nucleus, the lateral hypothalamic area and the septal nucleus had no effect on nociception. The microinjection rhIL-1 beta (20 pg/kg-50 pg/kg) into the ventromedial hypothalamus produced a prolongation of the paw-withdrawal latency. A maximal prolongation was obtained 10 min after the injection of rhIL-1 beta at 50 pg/kg. This reaction was also blocked by the simultaneous injection of IL-1ra (50 ng/kg) and Na salicylate (500 ng/kg). These findings indicate that IL-1 beta in the MPO and the VMH produces hyperalgesia and analgesia, respectively, while, in addition, both effects are mediated by IL-1 receptors and the synthesis of prostaglandins.
Oka
T
T
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Oka
K
K
Hosoi
M
M
Aou
S
S
Hori
T
T
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D006930:Hyperalgesia / Q000139:chemically induced*; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D011301:Preoptic Area / Q000187:drug effects*; D016548:Prosencephalon / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D012795:Sialoglycoproteins / Q000494:pharmacology; D012980:Sodium Salicylate / Q000494:pharmacology; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects*; D000521:alpha-MSH / Q000494:pharmacology
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; D000521:alpha-MSH; D012980:Sodium Salicylate