Weakened [corrected] taste-LPS association during endotoxin tolerance

In naive individuals, the administration of bacterial lipopolysaccharide (LPS) provokes a rapid systemic increase in pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6, inducing an acute phase response including sickness behavior. Strong associative...

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Bibliographic Details
Published in:Physiology & behavior 2008-01, Vol.93 (1-2), p.261-266
Main Authors: Pacheco-Lopez, G, Niemi, M-B, Engler, H, Engler, A, Riether, C, Doenlen, R, Espinosa, E, Oberbeck, R, Schedlowski, M
Format: Article
Language:English
Subjects:
Analysis of Variance
Animals
Association Learning - physiology
Conditioning, Classical - physiology
Drinking Behavior - physiology
Feeding Behavior - physiology
Interleukin-1beta - blood
Interleukin-6 - blood
Lipopolysaccharides - immunology
Male
Neuroimmunomodulation - immunology
Neuroimmunomodulation - physiology
Rats
Rats, Inbred Strains
Sick Role
Taste - immunology
Taste - physiology
Tumor Necrosis Factor-alpha - blood
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Summary:In naive individuals, the administration of bacterial lipopolysaccharide (LPS) provokes a rapid systemic increase in pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6, inducing an acute phase response including sickness behavior. Strong associative learning occurs when relevant gustatory/olfactory stimuli precede the activation of the immune system, affecting long-term individual food selection and nutritional strategies. Repeated LPS administration results in the development of an endotoxin tolerance status, characterized by a drastic reduction in the LPS-induced cytokine response. Here we investigated how the postprandial categorization of a relevant taste (0.2% saccharin) changed after administration of a high dose of LPS (0.5 mg/kg i.p.) in LPS-tolerant animals. Determination of the consummatory fluid intake revealed that, in contrast to LPS-naive rats, taste-LPS association did not occur during endotoxin tolerance. Ninety minutes after the single association trial, the plasma responses of TNF-alpha, IL-1beta and IL-6 were completely blunted in LPS-tolerant animals, which also resulted in low LPS-adipsogenic and LPS-anorexic effects. These findings indicate that an identical immune challenge can result in completely different neuro-behavioral consequences depending on the immune history of the individual, thus revealing part of the complex interconnection between the immune and neuro-endocrine systems in regulating food selection and consumption during the infectious process.
ISSN:0031-9384