Adiponectin and its receptors are expressed in adult ventricular cardiomyocytes and upregulated by activation of peroxisome proliferator-activated receptor γ

Abstract

Adiponectin is a protein hormone involved in maintaining energy homeostasis in metabolically active tissues. It enhances glucose and lipid metabolism via activation of AMP-dependent kinase (AMPK) in skeletal muscle and liver. Energy homeostasis is vital for the heart to work as a pump. In this study, we investigated whether adiponectin and its receptors are expressed in adult ventricular cardiomyocytes. We observed adiponectin transcript and protein in cultured ventricular cardiomyocytes isolated from adult rat, by quantitative real-time PCR, ELISA assays, Western blots, and immunofluorescent staining. In addition, we detected adiponectin receptor (AdipoR1 and AdipoR2) expression in the heart. AdipoR1 was expressed in rat myocardium at a level of about 50% of that in skeletal muscle; whereas adipoR2 was expressed at a similar level to that in liver. Rosiglitazone, a Peroxisome proliferator activated receptor γ (PPARγ) activator, substantially elevated expression of adiponectin in cultured cardiomyocytes and its secretion into cultured media. Rosiglitazone also increased adipoR1 and adipoR2 expression in cardiomyocytes. Treatment of recombinant globular adiponectin in cultured cardiomyocytes increased fatty acid oxidation and glucose uptake via activation of AMPK, suggesting a role for adiponectin in cardiac energy metabolism. Together, these data establish the existence of a local cardiac-specific adiponectin system that is regulated by PPARγ. Moreover, these findings indicate a role for adiponectin on normal myocardial energy homeostasis, in part, through the activation of AMPK.

Adiponectin effects and gene expression in rainbow trout: an in vivo and in vitro approach

“…In the same experiments, adiponectin increased FA oxidation, as previously demonstrated for other similar cellular models (Fruebis et al, 2001;Ceddia et al, 2005;Civitarese et al, 2006;Ding et al, 2007), perhaps due to increased carnitine palmitoyltransferase 1 (CPT1) activity (Ding et al, 2007;Li et al, 2007). Although an increased FA oxidation rate is associated with enhanced insulin sensitivity in mammals (Kadowaki et al, 2006), it still has not been tested for fish.…”

Estradiol stimulates mitochondrial biogenesis and adiponectin expression in skeletal muscle

“…Furthermore, adiponectin plays an important role in the regulation of mitochondrial content and function in other tissues such as skeletal muscle (Civitarese et al 2006). Although it was originally proposed that adiponectin was expressed and secreted only in adipose tissue, it has been shown to be also expressed in non-adipose tissues such as liver and muscle (Ding et al 2007, Krause et al 2008, Uribe et al 2008.…”

Myocardial Insulin Resistance: An Overview of Its Causes, Effects, and Potential Therapy

“…Dysregulation of the synthesis and secretion of these peptides has been associated with, and implicated in, the aetiology of metabolic diseases such as insulin resistance and type-2 diabetes. A possible role for adipokines in the regulation of myocardial metabolism only emerged recently [143][144][145].…”