Lipopolysaccharide (LPS) (strain O111:B4, Sigma Chemical Co., St. Louis, MO) dissolved in saline was injected at a dose of 0.33 or 1 mg/kg i.p. in volume 0.1 ml/10 g of body weight. In several experiments, a second LPS injection was made one week after the first injection. After each drug injection, mice were allowed to recover from sickness response to LPS (as judged by changes in body weight and water consumption and the recovery was monitored by daily measurement of body weight and water consumption) (Fig. 1). Usually one week was sufficient for complete recovery. Therefore, one week after the last LPS injection the mice were tested for voluntary ethanol intake. The schedule for LPS injection and alcohol consumption as well as monitoring of recovery from sickness in B6 inbred mice are presented in Fig. 1.
