Study summary · research use only
Anti-inflammatory effect of the ghrelin agonist growth hormone-releasing peptide-2 (GHRP-2) in arthritic rats
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this rat study, the ghrelin agonist growth hormone-releasing peptide-2 (GHRP-2) was administered to arthritic and control male Wistar rats after Freund's adjuvant injection, at 100 microg/kg daily for 8 days. The authors report that arthritis raised serum ghrelin and lowered leptin, and that GHRP-2 increased serum leptin and, in arthritic rats, lowered the arthritis score (10.4 +/- 0.8 vs. 13.42 +/- 0.47) and paw volume. Arthritis raised circulating IL-6 and nitrites/nitrates, and GHRP-2 lowered serum IL-6. In peritoneal macrophage cultures, GHRP-2 and ghrelin (10(-7) M) prevented endotoxin-induced IL-6 and reduced nitrite/nitrate release. The authors describe an anti-inflammatory action apparently mediated by ghrelin receptors on immune cells.
Abstract
Chronic arthritis induces hypermetabolism and cachexia. Ghrelin is a gastrointestinal hormone that has been proposed as a treatment to prevent cachexia. The aim of this work was to examine the effect of administration of the ghrelin agonist growth hormone-releasing peptide-2 (GHRP-2) to arthritic rats. Male Wistar rats were injected with Freund's adjuvant, and 15 days later arthritic and control rats were daily injected with GHRP-2 (100 microg/kg) or with saline for 8 days. Arthritis induced an increase in serum ghrelin (P < 0.01) and a decrease in serum concentrations of leptin (P < 0.01), whereas GHRP-2 administration increased serum concentrations of leptin. GHRP-2 increased food intake in control rats but not in arthritic rats. However, in arthritic rats GHRP-2 administration ameliorated the external symptoms of arthritis, as it decreased the arthritis score (10.4 +/- 0.8 vs. 13.42 +/- 0.47, P < 0.01) and the paw volume. In addition, circulating IL-6 and nitrites/nitrates were increased by arthritis, and GHRP-2 treatment decreased the serum IL-6 levels (P < 0.01). To elucidate whether GHRP-2 is able to modulate IL-6 release directly on immune cells, peritoneal macrophage cultures were incubated with GHRP-2 or ghrelin, the endogenous ligand of the growth hormone (GH) secretagogue receptor. Both GHRP-2 (10(-7) M) and ghrelin (10(-7) M) prevented endotoxin-induced IL-6 and decreased nitrite/nitrate release from peritoneal macrophages in vitro. These data suggest that GHRP-2 administration has an anti-inflammatory effect in arthritic rats that seems to be mediated by ghrelin receptors directly on immune cells.
pepmg summarizes the peer-reviewed literature and links to every source — it sells nothing, ships nothing, and gives no medical, dosing, or human-use guidance. Don't just trust this summary: follow the citation to its source and read it yourself. Research use only.