title: Insulin like growth factor-1 (IGF-1) causes overproduction of IL-8, an angiogenic cytokine and stimulates neovascularization in isoproterenol-induced myocardial infarction in rats.
abstract: Angiogenesis factors are produced in response to hypoxic or ischemic insult at the site of pathology, which will cause neovascularization. Insulin like growth factor-1 (IGF-1) exerts potent proliferative, angiogenic and anti-apoptotic effects in target tissues. The present study was aimed to evaluate the effects of IGF-1 on circulating level of angiogenic cytokine interleukin-8 (IL-8), in experimentally-induced myocardial ischemia in rats. Male Sprague-Dawley rats were divided into control, IGF-1 treated (2 μg/kg/day subcutaneously, for 5 and 10 days), isoproterenol (ISO) treated (85 mg/kg, subcutaneously for two days) and ISO with IGF-1 treated (for 5 and 10 days). Heart weight, serum IGF-1, IL-8 and cardiac marker enzymes (CK-MB and LDH) were recorded after 5 and 10 days of treatment. Histopathological analyses of the myocardium were also done. There was a significant increase in serum cardiac markers with ISO treatment indicating myocardial infarction in rats. IGF-1 level increased significantly in ISO treated groups and the level of IGF-1 was significantly higher after 10 days of treatment. IL-8 level increased significantly after ISO treatment after 5 and 10 days and IGF-1 concurrent treatment to ISO rats had significantly increased IL-8 levels. Histopathologically, myocyte necrosis and nuclear pyknosis were reduced significantly in IGF-1 treated group and there were numerous areas of capillary sprouting suggestive of neovascularization in the myocardium. Thus, IGF-1 protects the ischemic myocardium with increased production of circulating angiogenic cytokine, IL-8 and increased angiogenesis.
authors.affiliation: Faculty of Medicine, Health and Molecular Sciences, James Cook University, Townsville 4811, Queensland, Australia. haleagrahara.nagaraja@jcu.edu.au
authors.forename: Nagaraja
authors.initials: N
authors.lastname: Haleagrahara
authors.forename: Srikumar
authors.initials: S
authors.lastname: Chakravarthi
authors.forename: Lisa
authors.initials: L
authors.lastname: Mathews
mesh_terms: D000818:Animals; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000627:therapeutic use; D016209:Interleukin-8 / Q000097:blood*; D007545:Isoproterenol / Q000633:toxicity; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016209:Interleukin-8; D007334:Insulin-Like Growth Factor I; D007545:Isoproterenol