title: Chronic social stress induces cardiomyocyte contractile dysfunction and intracellular Ca2+ derangement in rats.
abstract: Chronic psychosocial stress triggers cardiovascular diseases although underlying mechanisms are still elusive. This study examined the effect of social stress on cardiomyocyte contractile function and pathological changes in myocardium using the visible burrow system (VBS) model. Chronic social stress was induced using a mixed-sex VBS housing in adult Sprague-Dawley (SD) rats. Contractile and intracellular Ca(2+) properties were evaluated in isolated cardiomyocytes including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90)), maximal velocity of shortening/relengthening (± dL/dt), Fura-2 fluorescence intensity, and intracellular Ca(2+) decay. Myocardial histology was evaluated using Masson trichrome staining. Social stress led to depressed PS, ± dL/dt, shortened TPS and prolonged TR(90) compared with the unstressed controls. Baseline and electrically-stimulated rise in Ca(2+) were reduced whereas intracellular Ca(2+) decay was delayed in stressed rats. Histological analyses exhibited overt interstitial fibrosis and cardiomyocyte hypertrophy in stressed rats. The GSH/GSSG ratio (indicative of oxidative stress status) was reduced whereas oxidative protein carbonyl formation was elevated in stressed rats. Western blot analysis showed unchanged expression of superoxide dismutase 1 (SOD1), β(1)-adrenoceptor (β(1)-AR) levels, reduced sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a) levels, and elevated phosphorylation of the stress signaling protein kinase JNK but not ERK in myocardium from stressed rats. Short-term in vitro treatment of cardiomyocytes with the stress inducer phenylephrine mimicked cell damage and intracellular Ca(2+) mishandling, the effects of which were mitigated by antioxidant, JNK inhibition, carvedilol and SERCA2a adenovirus. These findings indicate that chronic social stress is detrimental to cardiac structure and function possibly via mechanisms associated with oxidative injury and intracellular Ca(2+) mishandling.
authors.affiliation: Division of Pharmaceutical Sciences, Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: Subat
authors.initials: S
authors.lastname: Turdi
authors.forename: Ming
authors.initials: M
authors.lastname: Yuan
authors.forename: Gail M
authors.initials: GM
authors.lastname: Leedy
authors.forename: Zhenbiao
authors.initials: Z
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
mesh_terms: D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000378:metabolism*; D002316:Cardiotonic Agents / Q000494:pharmacology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D008297:Male; D055595:Mechanical Phenomena; D009135:Muscular Diseases / Q000209:etiology* / Q000473:pathology*; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D009929:Organ Size; D010656:Phenylephrine / Q000494:pharmacology; D050050:Protein Carbonylation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013315:Stress, Psychological / Q000150:complications*; D013997:Time Factors; D014162:Transfection
chemical_list: D002316:Cardiotonic Agents; D004791:Enzyme Inhibitors; D018342:Receptors, Adrenergic, beta-1; D010656:Phenylephrine; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D005978:Glutathione; D002118:Calcium; D019803:Glutathione Disulfide