Nox4 (NADPH [Nicotinamide adenine dinucleotide phosphate] oxidase 4) is a major source of oxidative stress and is intimately involved in cardiac hypertrophy. DPP (Dipeptidyl peptidase)-4 inhibitor has been reported to regulate Nox4 expression in adipose tissues. However, its effects on Nox4 in cardiac hypertrophy are still unclear. We investigated whether DPP-4 inhibitor could ameliorate cardiac hypertrophy by regulating Nox4 and its downstream targets. Ang II (Angiotensin II; 1.44 mg/kg per day) or saline was continuously infused into C57BL/6J mice with or without teneligliptin (a DPP-4 inhibitor, 30 mg/kg per day) in the drinking water for 1 week. Teneligliptin significantly suppressed plasma DPP-4 activity without any significant changing aortic blood pressure or metabolic parameters such as blood glucose and insulin levels. It attenuated Ang II-induced increases in left ventricular wall thickness and the ratio of heart weight to body weight. It also significantly suppressed Ang II-induced increases in Nox4 mRNA, 4-hydroxy-2-nonenal, and phosphorylation of HDAC4 (histone deacetylase 4), a downstream target of Nox4 and a crucial suppressor of cardiac hypertrophy, in the heart. Exendin-3 (150 pmol/kg per minute), a GLP-1 (glucagon-like peptide 1) receptor antagonist, abrogated these inhibitory effects of teneligliptin on Nox4, 4-hydroxy-2-nonenal, phosphorylation of HDAC4, and cardiac hypertrophy. In cultured neonatal cardiomyocytes, exendin-4 (100 nmol/L, 24 hours), a GLP-1 receptor agonist, ameliorated Ang II-induced cardiomyocyte hypertrophy and decreased in Nox4, 4-hydroxy-2-nonenal, and phosphorylation of HDAC4. Furthermore, exendin-4 prevented Ang II-induced decrease in nuclear HDAC4 in cardiomyocytes. In conclusion, GLP-1 receptor stimulation by DPP-4 inhibitor can attenuate Ang II-induced cardiac hypertrophy by suppressing of the Nox4-HDAC4 axis in cardiomyocytes.
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