Systematic Analysis of the Cytokine and Anhedonia Response to Peripheral Lipopolysaccharide Administration in Rats
Subchronic restraint stress does not influence the anhedonic response to a subsequent LPS challenge. After the familiarization phase (data not shown), rats were exposed to 1 h of restraint stress daily for 5 consecutive days. Three days after the last stress session animals received an i.p. injection of either vehicle or 0.63 mg/kg LPS. Daily restraint stress reduced body weight (a). At the beginning of the test phase, rats that were stressed during the manipulation phase had a significant lower body weight than animals that were nonstressed ( g versus g, ; data not shown). A subsequent acute LPS challenge reduced weight in nonstressed rats and to a slightly lesser extent in stressed animals (b). Systemic LPS administration also reduced total volume intake (c) and sucrose preference (d), but no differences could be found between stressed and nonstressed rats. Dashed lines indicate chance level for sucrose preference. Graphs are plotted as mean + SEM ( per group). Data were analyzed by rmANOVA followed by independent samples -test. compared to NS + Veh, compared to S + Veh, and compared to S + LPS. NS: nonstressed, S: stressed, and Veh: vehicle.