(a) Adolescent and adult male rats were given an acute intraperitoneal (i.p.) challenge of sterile saline (white bars) or lipopolysaccharide (LPS; 250 µg/kg; gray bars), and plasma corticosterone concentrations were assessed 3 hours later (Experiment 1). (b) Additionally, in Experiment 1, plasma corticosterone was examined in adolescent and adult rats 3 hours after (i.p.) injection of sterile saline (white bars) or 4-g/kg ethanol (20%v/v; black bars). (c) Following intragastric (i.g.) intubation with 4-g/kg ethanol (20% v/v; hatched bars) or tap water in Experiment 2, plasma corticosterone concentrations were also assessed. Endotoxin in plasma was measured in animals from Experiments 1 and 2 three hours after administration of (d) LPS, (e) i.p. ethanol, or (f) i.g. ethanol. Note the marked difference in scale of the y-axis for LPS-exposed animals in panel d versus ethanol-exposed rats in panels e and f. In both Experiments 1 and 2, blood ethanol concentrations were measured in adolescent and adult rats following either (g) i.p. or (h) i.g. administration of vehicle versus ethanol. Main effects of Drug are indicated by a dollar sign ($) above the bar for each Age group, whereas main effects of Age are denoted by a horizontal line with a plus symbol (+). In the case of a significant Age x Drug interaction, asterisks (*) denote a significant effect of Drug within a given Age group. A pound sign (#) indicates a significant difference between adolescents and adults within a Drug condition.