High
glucose induces apoptosis of cardiomyocytes and
fibrosis of cardiac fibroblasts, contributing to
diabetic cardiomyopathy. In this work, we explore the production of
relaxin alterations and the significance of their receptor system components in the hearts of experimental
diabetic cardiomyopathy rats. We measured rat relaxin-1 (equivalent to human
relaxin-2), relaxin-3, RXFP1 and RXFP3
mRNA expression in the hearts of experimental
diabetic cardiomyopathy rats. Neonatal rat ventricular myocytes (NRVMs) and cardiac fibroblasts were treated with 5.5 mmol/l normal
glucose (NG) and 33 mmol/l high
glucose (HG) for 0, 6, 12, 24, 48 and 72 h. Rat relaxin-1, relaxin-3, RXFP1 and RXFP3
mRNA expression were determined by real-time PCR. In the present study, we offer the first evidence that Relaxin-1
mRNA significantly increased and Relaxin-3
mRNA expression decreased at 4 and 8 weeks after STZ in the hearts of diabetic rats. In addition, significant down regulation of the
mRNA expression of RXFP1 and RXFP3 was observed at 4 w after STZ; however, the
mRNA expression levels of RXFP1 and RXFP3 were increased at 8 weeks after STZ. Apoptotic NRVMs induced by high
glucose generate a decreased level of relaxin-1 and RXFP1. In HG-administered cardiac fibroblasts, Relaxin-1
mRNA was significantly increased and relaxin-3
mRNA was significantly decreased. Additionally, the
mRNA expression of RXFP1 was decreased, and the
mRNA expression of RXFP3 was increased. This results showed that an important role of relaxin-2, relaxin-3 and their receptors system in the regulation of
diabetic cardiomyopathy.