Molecular Pathways Involved in the Amelioration of Myocardial Injury in Diabetic Rats by Kaempferol

There is growing evidence that chronic hyperglycemia leads to the formation of advanced glycation end products (AGEs) which exerts its effect via interaction with the receptor for advanced glycation end products (RAGE). AGE-RAGE activation results in oxidative stress and inflammation. It is well known that this mechanism is involved in the pathogenesis of cardiovascular disease in diabetes. Kaempferol, a dietary flavonoid, is known to possess antioxidant, anti-apoptotic, and anti-inflammatory activities. However, little is known about the effect of kaempferol on myocardial ischemia-reperfusion (IR) injury in diabetic rats. Diabetes was induced in male albino Wistar rats using streptozotocin (70 mg/kg; i.p.), and rats with glucose level >250 mg/dL were considered as diabetic. Diabetic rats were treated with vehicle (2 mL/kg; i.p.) and kaempferol (20 mg/kg; i.p.) daily for a period of 28 days and on the 28th day, ischemia was produced by one-stage ligation of the left anterior descending coronary artery for 45 min followed by reperfusion for 60 min. After completion of surgery, rats were sacrificed and the heart tissue was processed for biochemical, morphological, and molecular studies. Kaempferol pretreatment significantly reduced hyperglycemia, maintained hemodynamic function, suppressed AGE-RAGE axis activation, normalized oxidative stress, and preserved morphological alterations. In addition, there was decreased level of inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and NF-κB), inhibition of active c-Jun N-terminal kinase (JNK) and p38 proteins, and activation of Extracellular signal regulated kinase 1/2 (ERK1/2) a prosurvival kinase. Furthermore, it also attenuated apoptosis by reducing the expression of pro-apoptotic proteins (Bax and Caspase-3), Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells, and increasing the level of anti-apoptotic protein (Bcl-2). In conclusion, kaempferol attenuated myocardial ischemia-reperfusion injury in diabetic rats by reducing AGE-RAGE/ mitogen activated protein kinase (MAPK) induced oxidative stress and inflammation.