Objective: To explore the expression of Ghrelin and high mobility group protein B1 (HMGB1) in the serum and the intestinal tissue of sepsis model rats, and to evaluate the effect of electro-acupuncture (EA) at Zusanli (ST36) on the expression of HMGB1 and Ghrelin.
Methods: Forty-eight male Wistar rats were randomly divided into four groups, i.e., the sham-operation (sham), the cecal ligation and puncture group (CLP), the CLP + EA at Zusanli (ST36) group (EA), and the CLP + Ghrelin receptor blocking agent + EA group (GHSRA), 12 in each group. A sepsis rat model was prepared by CLP. The incision of the abdominal wall was immediately sutured along the ventral midline for rats in the Sham group. In the EA group EA at Zusanli (ST36) was performed 20 min after CLP surgery with the constant voltage (2 - 100 Hz, 2 mA) for 30 min. In the GHSRA group, Ghrelin receptor blocking agent, [D-Arg1, D-Phe5, D-Trp79, Leu11]-substance P (700 nmol/kg), was administered through intravenous injection immediately after CLP, and 20 min later, EA at Zusanli (ST36) was performed in the same way as for rats in the EA group. Blood samples were withdrawn 12 h after CLP. The serum levels of Ghrelin and HMGB1 were detected using ELISA. Ghrelin expressions and the number of Ghrelin immunopositive cell in the jejunum were determined by immunohistochemistry. HMGB1 contents of the jejunum tissue were detected by Western blotting.
Results: Compared with the Sham group, the number of serum immunopositive cells and the expression of HMGB1 in the jejunum tissue significantly increased and levels of Ghrelin and the expression rate of immunopositive cells significantly decreased in the CLP group (P < 0.05). Compared with the CLP group, the number of serum immunopositive cells and the expression of HMGB1 in the jejunum tissue significantly decreased, but levels of Ghrelin and the expression rate of immunopositive cells significantly increased in the EA group (P < 0.05). Compared with the EA group, the number of serum immunopositive cells and the expression of HMGB1 in the jejunum tissue significantly increased in the GHSRA group (P < 0.05), but there was no statistical difference in levels of Ghrelin between the two groups (P > 0.05). The serum level of HMGB1 was negatively correlated with Ghrelin in the Sham group, the CLP group, and the EA group (r = -0. 528, P < 0.01).
Conclusions: EA at Zusanli (ST36) could inhibit the expression of HMGB1 in the jejunum of septic rats, and promote the expression of Ghrelin. The expression of HMGB1 was inhibited by Ghrelin receptor blocking agent, which suggested that the anti-inflammation of EA at Zusanli (ST36) might be associated with Ghrelin.