Changes in parasympathetic system in medulla oblongata in male pigs in the course of tachycardia-induced cardiomyopathy

Catabolic/Anabolic Imbalance Is Accompanied by Changes of Left Ventricular Steroid Nuclear Receptor Expression in Tachycardia-Induced Systolic Heart Failure in Male Pigs

BACKGROUND

Steroid hormones play an important role in heart failure (HF) pathogenesis, and clinical data have revealed disordered steroidogenesis in male patients with HF. However, there is still a lack of studies on steroid hormones and their receptors during HF progression. Therefore, a porcine model of tachycardia-induced cardiomyopathy corresponding to HF was used to assess steroid hormone concentrations in serum and their nuclear receptor levels in heart tissue during the consecutive stages of HF.

METHODS AND RESULTS

Male pigs underwent right ventricular pacing and developed a clinical picture of mild, moderate, or severe HF. Serum concentrations of dehydroepiandrosterone, testosterone, dihydrotestosterone, estradiol, aldosterone, and cortisol were assessed by enzyme-linked immunosorbent assay. Androgen receptor, estrogen receptor alpha, mineralocorticoid receptor, and glucocorticoid receptor messenger RNA levels in the left ventricle were determined by qPCR.The androgen level decreased in moderate and severe HF animals, while the corticosteroid level increased. The estradiol concentration remained stable. The quantitative real-time polymerase chain reaction revealed the downregulation of androgen receptor in consecutive stages of HF and increased expression of mineralocorticoid receptor messenger RNA under these conditions.

CONCLUSIONS

In the HF pig model, deteriorated catabolic/anabolic balance, manifested by upregulation of aldosterone and cortisol and downregulation of androgen signaling on the ligand level, was augmented by changes in steroid hormone receptor expression in the heart tissue.

Reduced vagal control of the heart in high-fat diet mice: a potential role of increased butyrylcholinesterase

Suppressed parasympathetic function is commonly present in cardiovascular diseases, aging, obesity, and various other health conditions. Impaired parasympathetic action is known as a detrimental factor and contributes to the adverse outcomes in these conditions. However, the underlying mechanisms remain to be fully addressed. In this study, using high-fat diet (HFD)-induced obese mice as a model, the potential peripheral mechanisms underlying the impaired parasympathetic vagal control of the heart was examined. The HFD induced obesity and metabolic disorder in mice. These obese mice exhibited an attenuated response in heart rate to vagal stimulation, indicating impairment of peripheral parasympathetic activity in the heart. In cholinergic function-related proteins in the atria, protein levels of choline transporter and vesicular acetylcholine transporter were not decreased but increased, and type 2 muscarinic receptors showed a trend toward a reduction in HFD mice atria as compared with regular diet (RD) mice controls. While the protein level of acetylcholinesterase was not different, butyrylcholinesterase (BChE) protein level showed a twofold increase in HFD mice atria as compared with RD mice. Functionally, inhibition of BChE activity partially and significantly improved the attenuated response in heart rate to vagal stimulation in HFD mice. Collectively, these data suggest that increased BChE activity in the atria may contribute to the decreased parasympathetic function in HFD-induced obese mice.