Ghrelin does not modulate angiogenesis in matrigel plug in normal and diet-induced obese mice

BACKGROUND: The reciprocal interaction between adipocytes and angiogenesis is considered as an essential component in the development and expansion of adipose tissue. The aim of this study was to evaluate the effect of ghrelin on angiogenic response using in vivo angiogenesis assay of matrigel plug and its correlation with serum leptin levels in normal and diet-induced obese mice. MATERIALS AND METHODS: This experimental study has been done on 24 male C57BL/6 mice which were randomly divided into four groups: Normal diet (ND) or control, ND + ghrelin, high-fat-diet (HFD) or obese and HFD + ghrelin (n = 6/group). Obese and control groups received HFD or standard diet for 14 weeks. Then, growth factor reduced matrigel plug (500 μl) containing bFGF (basic fibroblast growth factor; 100 ng) with or without ghrelin (100 μg/kg) was injected subcutaneously in the mid-ventral abdominal region of each mice. After 10 days, blood samples were taken and matrigel plugs were removed under anesthesia and angiogenic response was assessed by immunohisochemical staining. RESULTS: HFD significantly increased angiogenesis in matrigel plug as expressed as the number of CD31-positive cells than standard diet (43 ± 5 vs. 13 ± 2.5 CD31(+) cells/field). Ghrelin did not alter angiogenesis in matrigel plug in both obese and control groups. There was a strong positive correlation between the number of CD31-positive cells and serum leptin concentration (r = 0.91). CONCLUSION: Leptin as an angiogenic factor has a positive correlation with angiogenesis in matrigel plug model of angiogenesis and ghrelin could not alter angiogenesis.