Cytokine-induced fever in obese (fa/fa) and lean (Fa/Fa) Zucker rats.
In earlier work, we reported that genetically obese (fa/fa) Zucker rats exhibited significantly greater anorexia than did lean (Fa/Fa) Zucker rats to intracerebroventricular infusion of interleukin (IL)-1beta. Here, we investigated the fever response of obese (fa/fa) and lean (Fa/Fa) Zucker rats to intracerebroventricular microinfusion of IL-1beta as well as to the following other cytokines: IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha). Core body temperature was monitored by a radiotelemetry system in freely moving rats. The results show that 1) both IL-1beta and IL-6 induce fevers in obese and lean rats; 2) IL-1beta induces a significantly higher fever response in obese rats than it does in lean rats; 3) IL-6 induces a significantly higher fever response in lean rats than it does in obese rats; 4) IL-2 induces a moderate fever response in lean but not obese rats; 5) TNF-alpha induces a similar fever response in obese and lean rats; and 6) the fevers induced by each effective cytokine have different time courses. Thus obese (fa/fa) and lean (Fa/Fa) Zucker rats show differential responsiveness to the intracerebroventricular microinfusion of various classes of cytokines. This suggests that genetic obesity in the fa/fa Zucker rat is associated with differential cytokine action on thermoregulatory mechanisms.
Department of Biological Sciences, University of Delaware, Newark, Delaware 19716-2590, USA.
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Plata-Salamán
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Peloso
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Satinoff
D000818:Animals; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000235:genetics* / Q000502:physiology; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D016207:Cytokines / Q000008:administration & dosage / Q000494:pharmacology*; D005334:Fever / Q000139:chemically induced / Q000503:physiopathology*; D007263:Infusions, Parenteral; D007375:Interleukin-1 / Q000008:administration & dosage / Q000494:pharmacology*; D007376:Interleukin-2 / Q000008:administration & dosage / Q000494:pharmacology; D015850:Interleukin-6 / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000494:pharmacology
D016207:Cytokines; D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha