Research Article

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

Figure 2

Systemic LPS administration causes sickness and anhedonia in a dose- and time-dependent manner. Intraperitoneal LPS injection induced sickness behavior, as seen by reduced locomotor activity in the open field test (OFT) (a) and decreased total volume intake in the sucrose preference test (SPT) (c). At 24 h after administration, a dose of 0.63 and 1.25 mg/kg LPS reduced sucrose preference (d), thereby potentially indicating development of anhedonia. However, a single i.p. injection of LPS did not induce clear depressive-like behavior in the forced swim test (FST) (b). Please note that in the OFT and FST naive animals were used at all time points, whereas in the SPT rats were tested repeatedly. Dashed lines indicate chance level for sucrose preference. Graphs are plotted as mean + SEM ( per group). OFT and FST data were analyzed by multivariate ANOVA, SPT data by rmANOVA, and followed by independent samples -test. ; compared to 0 mg/kg LPS group; compared to 0 mg/kg LPS group in absence of rmANOVA effects.