Cytokines and thermoregulation: interleukin-9 injected in preoptic area fails to evoke fever in rats.
A number of the members of the family of cytokines including IL-1, IL-2, IL-6, and IL-11 act directly in the brain to induce a febrile response in the rat and other species. The purpose of this study was to examine the effect of interleukin-9 (IL-9) when this cytokine is applied directly to the thermosensitive and pyrogen reactive region of the anterior hypothalamic, preoptic area (AH/POA). In male Sprague-Dawley rats, guide cannulae for microinjection into the AH/POA were implanted stereotaxically, and radio transmitters for monitoring body temperature (Tb) were placed intraperitoneally. Following postoperative recovery, recombinant murine macrophage inflammatory protein (MIP)-1 beta was microinjected in the AH/POA of each rat in a dose of 28 pg/microliters to identify pyrogen reactive sites in the AH/POA. Then recombinant human IL-9 was suspended in pyrogen-free CSF vehicle and microinjected in the same sites in concentrations of 2.4, 24, and 240 U/microliters. In contrast to the pyrexic action of MIP-1 beta, IL-9 failed to elicit a significant alteration in the Tb of the rats at any of the doses tested. IL-9 was also without effect on the intakes of either water or food. These results demonstrate that IL-9 applied to the region of the diencephalon in which other cytokines act to evoke fever may not play a direct role in the thermogenic component underlying the acute phase response. However, as demonstrated in several different cell systems, IL-9 may require a cofactor related to pyrogen for a febrile response to develop.
Lopez-Valpuesta
F J
FJ
Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858-4354.
Myers
R D
RD
D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001833:Body Temperature Regulation / Q000502:physiology*; D001931:Brain Mapping; D016207:Cytokines / Q000502:physiology*; D005334:Fever / Q000139:chemically induced*; D007267:Injections; D016906:Interleukin-9 / Q000008:administration & dosage* / Q000494:pharmacology; D008297:Male; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D016207:Cytokines; D016906:Interleukin-9