Role of IL-6 in cytokine-induced sickness behavior: a study with IL-6 deficient mice

• Published in: Physiology & behavior Vol. 70; no. 3; pp. 367 - 373
• Main Authors: Bluthé, Rose-Marie, Michaud, Bruno, Poli, Valeria, Dantzer, Robert
• Format: Journal Article
• Language: English
• Published: Cambridge Elsevier Inc 01-08-2000; New York, NY Elsevier
• Subjects: Anatomical correlates of behavior; Animals; Behavior; Behavioral psychophysiology; Biological and medical sciences; Body weight; Body Weight - drug effects; Brain; Cytokines - pharmacology; Exploratory Behavior - drug effects; Fundamental and applied biological sciences. Psychology; Injections, Intraventricular; Interleukin-1; Interleukin-1 - administration & dosage; Interleukin-1 - pharmacology; Interleukin-6; Interleukin-6 - deficiency; Interleukin-6 - physiology; Knock-out mice; Life Sciences; Lipopolysaccharide; Lipopolysaccharides - pharmacology; Male; Mice; Mice, Knockout; Motor Activity - drug effects; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Sick Role; sickness behavior; Brain; Interleukin-1; Knock-out mice; Body weight; Lipopolysaccharide; Behavior; Interleukin-6; Intraspecific relation; Cytokine; Rodentia; Central nervous system; Strain; Interleukin 6; Vertebrata; Animal activity; Mammalia; Spontaneous physical activity; Social behavior; Mouse; Social interaction; Animal; Comparative study; Brain (vertebrata); SOURIS KNOCK-OUT; LIPOPOLY SACCHARIDE; NEUROBIOLOGIE
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/S0031-9384(00)00269-9

Interleukin-6 (IL-6) is synthesized and released in response to the cytokine inducer lipopolysaccharide (LPS) and IL-1, and acts as an endogenous pyrogen. Systemic administration of LPS and IL-1 to mice induces signs of sickness, including reduction of social exploration, immobility and body weight loss. To assess the role of IL-6 in the induction of sickness behavior, male IL-6–deficient mice (IL-6 −/−, Balb/cAn genetic background) were used and compared to IL-6 +/+ littermates. The depressing effects of intraperitoneal LPS (2.5 μg/mouse) and IL-1β (1.0 μg/mouse) on behavior and change in body weight were more marked in IL-6 +/+ than in IL-6 −/− mice. The same difference was observed when mice were injected with LPS (5 ng/mouse) and IL-1β (1 ng/mouse) into the lateral ventricle of the brain (i.c.v.). These results show that IL-6 released at the periphery and /or in the central nervous system plays a role in the behavioral response to LPS and IL-1.