Glucagon-Like Peptide-1 Analog Liraglutide Protects against Diabetic Cardiomyopathy by the Inhibition of the Endoplasmic Reticulum Stress Pathway

Aim. This study aimed to investigate whether the glucagon-like peptide-1 analog liraglutide (LIRA) can protect against diabetic cardiomyopathy and explore the related mechanism. Methods. Rats were divided into 6 groups: a nondiabetic group, diabetic cardiomyopathy rats without LIRA treatment, diabetic cardiomyopathy rats with LIRA treatment (with high-, medium-, and low-dose, resp.), and diabetic cardiomyopathy rats treated with insulin. Cardiac function was examined by echocardiography before and after treatment. The histopathology of the heart was examined with H&E staining. The mRNA levels of XBP1, ATF4, and TRAF2 were analyzed by RT-PCR, and the expression of glucose-regulated protein 78 (Grp78), enhancer-binding protein homologous protein (CHOP), caspase-3, and caspase-12 was detected by western blot. Results. LIRA strongly improved cardiac function from both echocardiographic and histopathologic analyses, but insulin only partly increased cardiac function by improving FS and LVPW values. LIRA treatment can significantly decrease the expression of XBP1, ATF4, and TRAF2 (P < 0.01). LIRA also significantly downregulates the expression of Grp78, caspase-3 (P < 0.01), CHOP, and caspase-12 (P < 0.05). Conclusions. LIRA can protect against diabetic cardiomyopathy by inactivating the ER stress pathway. The improvement in cardiac function by LIRA is independent of glucose control.