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BioMed Research International
Volume 2016, Article ID 9085273, 14 pages
http://dx.doi.org/10.1155/2016/9085273
Research Article

Systematic Analysis of the Cytokine and Anhedonia Response to Peripheral Lipopolysaccharide Administration in Rats

1BIOMED, Hasselt University, Agoralaan C Building, 3590 Diepenbeek, Belgium
2Neuroscience, Janssen Research & Development, Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium

Received 17 February 2016; Revised 27 May 2016; Accepted 14 June 2016

Academic Editor: Monica Fedele

Copyright © 2016 Steven Biesmans et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Inflammatory processes may cause depression in subsets of vulnerable individuals. Inflammation-associated behavioral changes are commonly modelled in rodents by administration of bacterial lipopolysaccharide (LPS). However, the time frame in which immune activation and depressive-like behavior occur is not very clear. In this study, we showed that systemic administration of LPS robustly increased circulating levels of corticosterone, leptin, pro- and anti-inflammatory cytokines, and chemokines. Serum concentrations of most analytes peaked within the first 6 h after LPS injection and returned to baseline values by 24 h. Chemokine levels, however, remained elevated for up to 96 h. Using an optimized sucrose preference test (SPT) we showed that sickness behavior was present from 2 to 24 h. LPS-induced anhedonia, as measured by decreased sucrose preference, lasted up to 96 h. To mimic the human situation, where depression develops after chronic inflammation, rats were preexposed to repeated LPS administration or subchronic restraint stress and subsequently challenged with LPS. While these procedures did not increase the duration of anhedonia, our results do indicate that inflammation may cause depressive symptoms such as anhedonia. Using our SPT protocol, more elaborate rodent models can be developed to study the mechanisms underlying inflammation-associated depression in humans.