TSH Effect On Cardiac Systolic Function In Cardiomyocytes

Aims:According this study, we wantedtoreveal a potentialeffect of TSH on diastolic and systolic dysfunctioninheart and had possible pathological and clinical implications for thepathogenesisthatassociated with subclinical hypothyroidism.Methods: The purecardiomyocytes were achievedby enzymatic disassociation and differential sticking wall method.Western-blot and immunofluorescencewere used todemonstrating that TSHR expressedin neonatal rat cardiomyocytes.TSH restrained calcium releasing captured by confocal microscope in concentration dependent manners.TSH down-regulated the expression of sarcoplasmic reticulum calcium ATPase(serca2a),ryanodine receptors 2and other molecular proteins related to the pathway in time- and concentration-dependent manners byReal-time quantitative PCR( RT-PCR) and western-blot.To explore the signal pathway involved in the effect of TSH regulated serca2 a, western-blot method was used to detect the expression of PKA,P-PKA,PLN,P-PLN,serca2 a after different concentration stimulation. Then the cells were stimulated by 20?mol/L H89 and 4?mol/L TSH for 24 hours respectively, serca2 a and P-PLN expression were detected by RT-PCR and western-blot.Result:weproved that TSHR expressed in cardiomyocytes and TSH could down-regulate serca2 a, Ryr2 in time- and concentration-dependent manners. After different concentration effect of TSH, P-PKA and P-PLN were depressed by western-blot detection.To evaluate whether TSH suppressed SERCA2 a by inhibiting PKA/PLN pathway, we treated the cells with TSH and H89 simultaneously, the treatment decreased P-PLN and SERCA2 a mRNA and protein levels as H89 independent did.Conclusions: In subclinical hypothyroidism, the degree of serum TSH increase and its long-lasting effect contributed to the development of cardiac diastolic and systolic dysfunction in subclinical hypothyroidism.TSH restrained the expression of serca2 a, Ryr2, calcium ion releasing followed various time- and concentration-stimulation and the effect on serca2 a was realized throughPKA/PLNsignaling pathway by actingon the TSHR incardiomyocytes.