Thomas Hubschle  , Sandra Rafalzik  , Rudiger Gerstberger  , Joachim Roth  , 
    Induction of Fever and Sickness Behavior in Telemetrically Monitored Rats  During Systemic Inflammation Induced by Zymosan,
    Journal of Animal and Veterinary Advances,
    Volume 6,Issue 4,
    2007,
    Pages 569-575,
    ISSN 1680-5593,
    javaa.2007.569.575,
    (https://makhillpublications.co/view-article.php?doi=javaa.2007.569.575)
    Abstract: Zymosan (Zy) has been shown to act as a pathogen-associated molecular pattern that activates the innate immune Toll-like receptor subtypes 2 and 6 (TLR2, TLR6). Systemic challenge with TLR2/6-agonists has been shown to mediate brain-controlled signs of sickness behavior amongst them fever, depressed motor activity, anorexia and adipsia. This study was designed to determine whether Zy as a further TLR2/6-agonist is also capable to induce similar sickness behavior responses during systemic Zy-induced inflammation as those observed with Mycoplasma-specific TLR2/6 agonists. In telemetrically monitored rats intraperitoneal treatment with 10 mg kg <SUP>1</SUP> Zy induced a moderate febrile response with significantly elevated abdominal temperatures ( T of about 1.2°C) for a period of about 4 h on the day of injection (day 1). Already at the end of day 1 temperature data of the Zy group returned to normal values of control animals and thereafter showed an almost identical circadian rhythm for the next 3 nights and 2 days. Zy-treated animals showed generally lower cumulative motor activities, however, significantly reduced only during night 1 and night 3. Cumulative food intake was significantly reduced during night 1 and night 2 in the Zy group, while no significant changes were measured for cumulative water intake. In line with the depressed food intake, Zy-treated rats developed a reduction  in  body weight gain that became significant on day 3 and day 4 after the injection. In conclusion, Zy-induced fever, anorexia and depressed motor activity seem to result from activation of cellular pathways involved in the TLR2/6-dependent innate immune responses.
    Keywords: Anorexia;body temperature;locomotor activity;telemetry;toll-like receptor 2 and 6;immune response