Curcumin alleviates isoproterenol-induced cardiac hypertrophy and fibrosis through inhibition of autophagy and activation of mTOR

OBJECTIVE: Curcumin has been reported to possess cardioprotective effects. However, the potential molecular mechanism of curcumin is still not clear. The aim of the present study was to investigate the role of curcumin in regulating autophagy and mammalian target of rapamycin (mTOR) signaling in isoproterenol-induced cardiac hypertrophy and fibrosis in the rat. MATERIALS AND METHODS: Rats model of cardiac hypertrophy and fibrosis was induced by isoprenaline (5 mg/kg/day. subcutaneous injection), which were treated with or without curcumin (200 mg/kg/day, intragastric administration). Masson's trichrome staining was performed to investigate the effect of curcumin on fibrosis of cardiac hypertrophy rat. The expression of hypertrophic and fibrosis markers was determined by RT-qPCR. The protein expression of autophagic markers, mTOR, and phosphorylated-mTOR (p-mTOR) was performed by Western blotting. RESULTS: Isoprenaline treatment significantly up-regulated the mRNA expression of hypertrophic (ANP and MYH7) and fibrotic (procollagen I and III) markers in the hearts from rats. All of these markers were reversed by curcumin treatment in isoproterenol-treated rats. Histological analysis showed that curcumin attenuated the interstitial fibrosis of heart triggered by isoproterenol. Moreover, isoproterenol significantly reduced the mRNA levels of mTOR and the protein expression of p-mTOR. However, isoprenaline caused a significant induction of the mRNA levels of LC3 and Beclin-1 and the protein expression of LC3-II and Beclin-1, as well as LC3-II/I ratio. Curcumin abolished these iso-prenaline-mediated changes in mTOR/autophagy signaling pathway. CONCLUSIONS: Our data demonstrated that curcumin targeted mTOR/autophagy axis could attenuate cardiac hypertrophy and fibrosis in a rat model.