High dietary taurine inhibits myocardial apoptosis during an atherogenic diet: association with increased myocardial HSP70 and HSF-1 but not caspase 3
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Background and aim
Apoptosis is a major cause of myocyte death, and taurine is anti-apoptotic. Heat shock protein 70 (HSP70) (which is regulated by heat shock factor—HSF-1) is also anti-apoptotic, and caspase 3 stimulates the apoptotic pathway. This study investigated whether taurine affects atherogenic diet-induced myocardial apoptosis, and whether HSP70, HSF-1 and caspase 3 are involved.
New Zealand white rabbits were divided into 3 groups for 4 weeks according to their diet. Group 1 (control) was fed a normal rabbit diet; Group 2 (MC) received a normal rabbit diet with 1 % methionine plus 0.5 % cholesterol. Group 3 received MC diet + 2.5 % taurine (MCT).
The atherogenic diet did not affect myocardial HSP70 or HSF-1 protein, but increased myocardial apoptotic nuclei to 40 % (p < 0.01) versus 7 % in con and 12 % in MCT (p < 0.01). However, in MCT, myocardial HSP70 expression increased by 42.7 % versus con and MC (p = 0.016), HSF-1 by 12 % versus con and MC (p < 0.05), and total nuclei count increased by 37 % versus MC (p < 0.05). Caspase 3 subunits remained unchanged in all groups, and HSP70 was increased approximately twofold in endothelial layer of arterioles (p = 0.01).
This study shows that taurine could reduce myocardial apoptotic nuclei and thus confer myocardial cytoprotection via stimulating myocardial HSP70 via HSF-1 and caspase 3-independent mechanisms.