BACKGROUND: Stress cardiomyopathy (SCM) currently has a high incidence in older adults, and the theories regarding its causes include "catecholamine myocardial toxicity" and "sympathetic hyperactivation". However, the role of the central nervous system in the pathogenesis of SCM remains unknown. We investigated the role of microglia activation in the paraventricular hypothalamic nucleus (PVN) in the development of SCM. METHODS: An SCM model was created using male Sprague-Dawley (SD) rats, immobilized for 6 h every day for a week. Electrocardiogram, cardiac electrophysiology, and echocardiography examinations were performed to verify the changes in cardiac structure and function in rats with SCM. RNA sequencing was used to explore the changes in the hypothalamus during SCM. In addition, brain and heart tissues were collected to detect microglial activation and sympathetic activity. RESULTS: The main findings were as follows: (1) immobilization stress successfully induced SCM in SD rats; (2) microglia were significantly activated in the hypothalamus, as evidenced by cytosol thickening, increases in the number of microglial branches, and microglia enriched in the PVN; (3) in SCM, the microglia in the PVN exhibited increased central and peripheral cardiac sympathetic activity and increased the expression of neuroinflammatory factors; and (4) it is possible that inhibiting microglial activation could suppress the sympathetic activity of the central nervous system and heart and increase cardiac electrical stability in SCM rats. CONCLUSIONS SCM was induced in SD rats by immobilization stress, acting through the activation of the hypothalamic microglia. The activated microglia were specifically enriched in the PVN, increasing the activity of the central and peripheral sympathetic nervous systems by regulating the expression of neuro-inflammatory factors, mediating dysfunction of the left ventricle, and increasing the susceptibility to ventricular arrhythmias.

BACKGROUNDOsteoporosis is a common complication of chronic obstructive pulmonary disease (COPD). Recent clinical and biological researches have increasingly delineated the biomolecular pathways of bone metabolism regulation in COPD. We extended this work by examining the specific association and potential contribution of the osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL) axis to the pathogenesis of osteoporosis in advanced COPD. The aim of this study was to assess the relationships of serum OPG, RANKL, and tumor necrosis factor-alpha (TNF-μ) with bone turnover in men with very severe COPD.

METHODSPulmonary function, T-score at the lumbar spine (LS) and femoral neck (FN), serum OPG, RANKL, soluble receptor of tumor necrosis factor-alpha-I and II (sTNFR-I, sTNFR-II), osteocalcin (OC), and β-CrossLaps (βCL) levels were measured in 45 men with very severe stage COPD and 36 male non-COPD volunteers. COPD patients and healthy controls were compared using an independent t-test and Mann-Whitney U-test. The Pearson coefficient was used to assess the relationships between variables.

RESULTSOPG and OC were lower in male COPD patients than in control subjects whereas RANKL, serum βCL, TNF-μ, and its receptors were higher. OPG directly correlated with forced expiratory volume in 1 s (FEV1) % predicted (r = 0.46, P < 0.005), OC (r = 0.34, P < 0.05), LS (r = 0.56, P < 0.001), and FN T-score (r = 0.47, P < 0.01). In contrast, serum RANKL inversely associated with LS and FN T-score (r = -0.62, P < 0.001 and r = -0.48, P < 0.001) but directly correlated with βCL (r = 0.48, P < 0.001). In addition, OPG was inversely correlated with RANKL (r = -0.39, P < 0.01), TNF-μ (r = -0.56, P < 0.001), and sTNFR-I (r = -0.40, P < 0.01).

CONCLUSIONOur results suggest that serum OPG and RANKL levels are inversely associated with bone loss in men with advanced stage COPD.

Bone Density ; physiology ; Cross-Sectional Studies ; Humans ; Male ; Middle Aged ; Osteoporosis ; metabolism ; pathology ; Osteoprotegerin ; metabolism ; Pulmonary Disease, Chronic Obstructive ; metabolism ; pathology ; RANK Ligand ; metabolism ; Respiratory Function Tests ; Tumor Necrosis Factor-alpha ; metabolism