β-Adrenoreceptor Agonist Isoproterenol Alters Oxidative Status, Inflammatory Signaling, Injury Markers and Apoptotic Cell Death in Myocardium of Rats.

Sustained high levels of circulating catecholamines are reported to induce cardiotoxicity. Isoproterenol (ISP), a synthetic catecholamine has been widely employed to induce myocardial injury, though the role of inflammation and apoptosis is not well established. This study was designed to investigate the underlying mechanism of oxidative damage, inflammatory signaling, cell death in ISP induced myocardial infarction in rats. Wistar albino rats were divided in two groups: group I (sham control) and group II (ischemic control). ISP (85 mg/kg, s.c.) was administered at an interval of 24 h to group II for two consecutive days. On day third, after 48 h of the first injection of ISP, blood was collected from retro orbital plexus of rat eyes to estimate the biochemical parameters. Glutathione (GSH) and superoxide dismutase (SOD) were measured for antioxidant status. Similarly, malondialdehyde (MDA) was measured as an index of lipid peroxidation. Cardiac markers (SGOT, CK-MB, TropI and LDH) and pro-inflammatory cytokines (IL-6, CRP and TNF-α) were also estimated in ISP-induced rats. At the end of experiments animals were sacrificed for histopathological studies. GSH and SOD showed significant decrease after ISP challenge as compared to sham (control) group (p < 0.01) while MDA level, increased significantly (p < 0.01). ISP, also increased the level of cardiac markers and markers of inflammation significantly (p < 0.01), which was further verified by histopathological studies of the heart tissues. The study confirmed that ISP causes detrimental changes in the myocardium by altering cardiac and inflammatory markers, which leads to severe necrosis. The deleterious effects produced by ISP substantiate its suitability as a novel animal model for evaluation of cardioprotective agents/drugs.