The effects of coadministration of ghrelin agonist (GHRP-2) and GH on TNF-α, IL-6, and iNOS genes expression induced by LPS in mouse liver

Abstract

Growth hormone (GH)-releasing peptide-2 (GHRP-2), a ghrelin receptor agonist, has been reported to bear an anti-inflammatory effect. The aim of this study is to assess the impact of GHRP-2 and GH on the expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS) genes induced by lipopolysaccharide (LPS) in mouse liver tissues. Thirty-five male NMRI mice (25 ± 5 g) were used. Mice were divided into five groups (n = 7). GHRP-2 (100 μg/kg), GH (25 μg/kg), and (GHRP-2 + GH) were injected through the mice tail vein 30 min before the injection of LPS. Then, inflammation was induced by intraperitoneal injection of LPS (5 mg/kg) while the control animals received sterile saline. Changes in the levels of expression of TNF-α, IL-6, and iNOS genes in the mice liver induced by LPS injection for 2 h were studied by a semiquantitative RT-polymerase chain reaction method. Administration of LPS increased hepatic TNF-α, IL-6, and iNOS mRNAs. The results showed that intravenous administration of GHRP-2and GH significantly reduced the elevated TNF-α, IL-6, and iNOS mRNA levels 2 h after the injection. In contrast, injection of GHRP-2 prior to injection of LPS reduced IL-6. Injection of GH reduced the expression of iNOS in liver tissues. Coadministration of two drugs had a positive effect on the reduction of TNF-α, IL-6, and iNOS expression.