Activation of M 3 muscarinic acetylcholine receptors delayed cardiac aging by inhibiting the Caspase-1/IL-1β Signaling Pathway

Abstract

Background/Aims: Because the prevalence of age-related cardiac impairment increases as the human lifespan increases, it is important to combat the effects of aging. Recently, the cardiac M 3 muscarinic acetylcholine receptor (M 3 -mAChR) has been demonstrated to play important roles in cardiac development and in the pathogenesis of cardiac diseases. However, the role of M 3 -mAChR in aging remains largely unknown. Therefore, the aim of this study was to investigate the involvement of M 3 -mAChR in the progression of cardiac aging. Methods: We established a cardiac aging model in mice through subcutaneous injection with D-galactose at a dose of 100 mg/kg/day for 6 weeks. D-galactose was also used to induce aging in primary cultured neonatal mouse cardiomyocytes. The myocardium from mice was stained with hematoxylin and eosin for histological analysis. The protein expression levels of p53 and p21 were determined using western blotting. The mRNA and protein expression levels of M 3 -mAChR, caspase-1, and interleukin (IL)-1β were determined using real-time PCR, immunohistochemical staining, and western blotting. Results: The expression of M 3 -mAChR was down-regulated in the myocardium from aged mice and D-galactose-treated mice, while the expression levels of caspase-1 and its downstream molecule IL-1β were significantly increased. The M 3 -mAChR agonist choline reduced the increase in caspase-1 in cardiomyocytes induced by D-galactose, which was reversed by the M 3 -mAChR antagonist 4-DAMP. Moreover, 4-DAMP promoted D-galactose-induced cardiomyocyte aging, which was attenuated by a caspase-1 inhibitor. Conclusion: Activation of M 3 -mAChR delayed cardiac aging by inhibiting the caspase-1/IL-1β signaling pathway.