Cardioprotective effects of lipoic acid, quercetin and resveratrol on oxidative stress related to thyroid hormone alterations in long-term obesity

Abstract

This study investigated possible mechanisms for cardioprotective effects of lipoic acid (LA), quercetin (Q) and resveratrol (R) on oxidative stress related to thyroid hormone alterations in long-term obesity. Female C57BL/6 mice were fed on high-fat diet (HFD), HFD+LA, HFD+R, HFD+Q and normal diet for 26weeks. Body weight, blood pressure, thyroid hormones, oxidative stress markers, angiotensin converting enzyme (ACE), nitric oxide synthase (NOS) and ion pump activities were measured, and expression of cardiac genes was analyzed by real-time polymerase chain reaction. HFD induced marked increase (P<.05) in body weight, blood pressure and oxidative stress, while plasma triidothyronine levels reduced. ACE activity increased (P<.05) in HFD mice (0.69±0.225U/mg protein) compared with controls (0.28±0.114U/mg protein), HFD+LA (0.231±0.02U/mg protein) and HFD+Q (0.182±0.096U/mg protein) at 26weeks. Moreover, Na(+)/K(+)-ATPase and Ca(2+)-ATPase activities increased in HFD mice whereas NOS reduced. A 1.5-fold increase in TRα1 and reduction in expression of the deiodinase iodothyronine DIO1, threonine protein kinase and NOS3 as well as up-regulation of AT1α, ACE, ATP1B1, GSK3β and Cja1 genes also occurred in HFD mice. Conversely, LA, Q and R inhibited weight gain; reduced TRα1 expression as well as increased DIO1; reduced ACE activity and AT1α, ATP1B1 and Cja1 gene expression as well as inhibited GSK3β; increased total antioxidant capacity, GSH and catalase activity; and reduced blood pressure. In conclusion, LA, resveratrol and quercetin supplementation reduces obesity thereby restoring plasma thyroid hormone levels and attenuating oxidative stress in the heart and thus may have therapeutic potential in heart diseases.

Keywords: Angiotensin converting enzyme; Antioxidants; Cardioprotection; Long-term obesity; Oxidative stress; Thyroid hormones.