Effects of lipopolysaccharide challenge and weaning on serum biochemical parameters and hepatic hepcidin gene expression in piglets

Hepcidin is a liver-derived peptide hormone that acts as a key regulator of intestinal iron absorption with antimicrobial properties in mammals, and its expression can be regulated by multiple stimuli. Two experiments were conducted to investigate the effects of lipopolysaccharide (LPS) challenge and weaning on serum parameters and hepatic hepcidin gene expression in piglets. In Exp. 1, 10 suckling piglets were randomly divided into a control group and a LPS group, with 5 piglets per group. The LPS group pigs were injected with 100 μg/kg BW LPS on suckling d 3, 5, and 7, and the control group piglets were injected with normal saline at the same dose. All piglets were sacrificed on d 7, and blood, liver, and spleen samples were collected. Total iron contents in the liver and serum were decreased (P < 0.05) in the LPS group. Serum total protein, albumin, total bilirubin, glucose, and triglyceride levels were reduced (P < 0.05) in the LPS group. Activities of serum Cu/Zn superoxide dismutase, catalase, and phospholipid hydroperoxide glutathione peroxidase were also decreased (P < 0.05) in the LPS group. However, erythrocyte malondialdehyde content was increased (P < 0.05) by the LPS challenge. Hepatic hepcidin mRNA abundance was increased (P < 0.05) in the LPS group compared with the control group. In Exp. 2, 55 piglets were randomly taken from 5 different sows at 21 d of age, and 5 piglets were sacrificed right before weaning at the age of 21 d. The remaining 50 piglets were weaned and divided into 5 pens with 10 pigs per pen. The weaning pigs were fed a corn and soybean meal–based weaning diet, and 1 pig per pen was sacrificed on d 2, 4, and d 8 after weaning. The alkaline phosphatase (AP) activity in serum was highest right before weaning and decreased (P < 0.05) after weaning. Serum Na, Cl, and K ion levels were not different (P > 0.05) before and after weaning. Serum globulin content was reduced (P < 0.05) on d 2 and was increased (P < 0.05) on d 4 and 8 after weaning. The hepatic hepcidin mRNA abundance was the lowest (P < 0.05) before weaning, peaked on d 2, and was then reduced (P < 0.05) on d 4 and 8 after weaning. In conclusion, LPS challenge and weaning enhanced hepatic hepcidin mRNA abundances whereas weaning decreased serum AP activity in the piglets.