Anti-apoptotic effect of magnolol in myocardial ischemia and reperfusion injury requires extracellular signal-regulated kinase1/2 pathways in rat in vivo.
Magnolol, an active component extracted from Magnolia officinalis, has been reported to have protective effect on ischemia and reperfusion (I/R)-induced injury in experimental animals. The aim of the present investigation was to further evaluate the mechanism(s) by which magnolol reduces I/R-induced myocardial injury in rats in vivo. Under anesthesia, left anterior descending (LAD) coronary artery was occluded for 30 min followed by reperfusion for 24 h (for infarct size and cardiac function analysis). In some experiments, reperfusion was limited to 1 h or 6 h for analysis of biochemical and molecular events. Magnolol and DMSO solution (vehicle) were injected intra-peritoneally 1 h prior to I/R insult. The infarct size was measured by TTC technique and heart function was monitored by Millar Catheter. Apoptosis related events such as p-ERK, p-Bad, Bcl-xl and cytochrome c expression were evaluated by Western blot analysis and myocardial caspase-3 activity was also measured. Magnolol (10 mg/kg) reduced infarct size by 50% (P < 0.01 versus vehicle), and also improved I/R-induced myocardial dysfunction. Left ventricular systolic pressure and positive and negative maximal values of the first derivative of left ventricular pressure (dP/dt) were significantly improved in magnolol-treated rats. Magnolol increased the expression of phosphor ERK and Bad which resulted in inhibition of myocardial apoptosis as evidenced by TUNEL analysis and DNA laddering experiments. Application of PD 98059, a selective MEK1/2 inhibitor, strongly antagonized the effect of magnolol. Taken together, we concluded that magnolol inhibits apoptosis through enhancing the activation of ERK1/2 and modulation of the Bcl-xl proteins which brings about reduction of infarct size and improvement of cardiac function in I/R-induced injury.
Jin
Yong Chun
YC
Department of Pharmacology, School of Medicine and Institute of Health Sciences, Gyeongsang National University, 92 Chilamdong, Jinju, 660-751, Korea.
Kim
Kil Jung
KJ
Kim
Young Min
YM
Ha
Yu Mi
YM
Kim
Hye Jung
HJ
Yun
Ui Jung
UJ
Bae
Ki Hwan
KH
Kim
Yeong Shik
YS
Kang
Sam Sik
SS
Seo
Han Geuk
HG
Lee
Jae Heun
JH
Chang
Ki Churl
KC
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D004195:Disease Models, Animal; D005419:Flavonoids / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D017705:Lignans / Q000494:pharmacology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009203:Myocardial Infarction / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology* / Q000517:prevention & control; D010936:Plant Extracts / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
D001713:Biphenyl Compounds; D005419:Flavonoids; D017705:Lignans; D010936:Plant Extracts; D019253:Proto-Oncogene Proteins c-bcl-2; C005498:magnolol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D053148:Caspase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one