Astaxanthin protects fludrocortisone acetate-induced cardiac injury by attenuating oxidative stress, fibrosis, and inflammation through TGF-β/Smad signaling pathway.

Hypertensive rats serve as a good experimental model for studying the pathophysiology of cardiac hypertrophy and remodeling leading to heart failure. In this study, we aimed to analyze the effect of astaxanthin and possible mechanisms involved in alleviating oxidative stress, fibrosis and inflammation that triggers cardiac remodeling using male uninephrectomized Long Evans rats. Cardiac hypertrophy and hypertension were induced in rats termed as 'FCA-Salt rats' by an oral administration of fludrocortisone acetate (FCA) and 1 % NaCl in drinking water. Biochemical assays showed that FCA-Salt rats exhibited an upregulation of oxidative stress markers AOPP, MDA and downregulation of NO in heart and kidney, which was reversed by astaxanthin treatment. Astaxanthin further regularized the reduced activities of antioxidant enzymes GSH, SOD and CAT in these tissues. ELISA revealed that astaxanthin significantly reduced the inflammatory response by reducing the elevated levels of IL-1β, IL-17a, and TNF-α and pro-fibrotic marker TGF-β1 in plasma. Real-time qPCR depicted an upregulation of TNF-α, IL-1β, IL-6, IL-17A as well as signaling molecules TGF-β1, Smad2 and Smad3 in heart of FCA-Salt rats, which was reduced significantly by astaxanthin. Sirius red staining showed that the cardiac and renal fibrosis was significantly improved by astaxanthin treatment. Together, our results suggest that astaxanthin treatment is beneficial in protecting cardio-renal damage in hypertension through TGF-β/Smad signaling pathway, hence, this molecule may be considered for the maintenance of cardio-renal health.