Gene and protein expression and serum iron levels in suckling and weaned mice treated with LPS. Fifteen-day-old and 25- to 28-day-old C57BL/6J mice were injected intraperitoneally with either 1 mg/kg LPS in sterile saline or sterile saline alone. Four hours after injection, the mice were euthanized and tissues were taken. Relative hepatic (A) Saa1 and (B) Hamp1 mRNA expression, the (C) level of ferroportin protein in isolated duodenal enterocytes, and the (D) serum iron concentration were determined. Gene expression levels were calculated relative to the housekeeping gene Hprt and are expressed as a proportion of the 25- to 28-day-old saline-injected group. Ferroportin protein expression levels were calculated relative to β-actin and are expressed as a proportion of saline-injected controls at each time point. (C) A representative blot is shown. The number of mice analyzed in each group is indicated in parentheses under each bar. The data represent means ± SEM. 15d, 15 days old; Fpn, ferroportin; L, LPS-injected mice; 25-28d, 25–28 days old; S, saline-injected mice. *P < .05; #P < .01.