The participation of ferroptosis in fibrosis of the heart and kidney tissues in Dahl salt-sensitive hypertensive rats

Abstract

Abstract Background and Purpose Hypertension is considered a major risk factor for cardiovascular diseases, and salt-sensitive hypertension is often more prone to induce damage to target organs such as the heart and kidneys. Abundant recent studies have demonstrated a close association between ferroptosis and cardiovascular diseases. Therefore, this study aimed to investigate whether ferroptosis is involved in the occurrence and development of myocardial fibrosis and renal fibrosis in salt-sensitive hypertensive rats, providing new insights into the mechanisms underlying target organ damage in salt-sensitive hypertension. Methods Ten 7-week-old male Dahl salt-sensitive (Dahl-SS) rats were randomly divided into two groups after 1 week of adaptation feeding. One group received a regular diet containing 0.3% NaCl (Normal Diet Saline, NDS group), and the other group received a high-salt diet containing 8% NaCl (High Diet Saline, HDS group) for 8 consecutive weeks. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) of Dahl-SS rats were measured and recorded weekly. Structural changes in the heart and kidney tissues of Dahl-SS rats were observed using HE staining and Masson staining. Ultrastructural morphological changes in the heart and kidney tissues of Dahl-SS rats were observed under transmission electron microscopy. Prussian blue staining was used to observe iron deposition in the heart and kidney tissues of Dahl-SS rats. Iron content and malondialdehyde (MDA) content in the heart and kidney tissues of Dahl-SS rats were quantitatively compared using a colorimetric method. Lastly, protein expression of xCT and GPX4 in the heart and kidney tissues of Dahl-SS rats was detected using immunofluorescence and Western blot techniques. Results At the end of 8 weeks, compared to the NDS group, rats in the HDS group showed significantly elevated systolic blood pressure (SBP) and diastolic blood pressure (DBP) (P < 0.05). Disordered arrangement of myocardial cells and cell swelling were observed; glomerular solidification, partial renal tubules atrophy, and disordered arrangement were evident. Additionally, collagen fiber deposition significantly increased in the cardiac interstitium, glomeruli, and renal tubular interstitium (P < 0.01). Transmission electron microscopy revealed characteristic changes of ferroptosis in the ultrastructure of the heart and kidney tissues of rats in the HDS group, including reduced or disappeared mitochondria volume, decreased or vanished cristae, and increased density of mitochondrial double membranes. Prussian blue staining confirmed iron deposition in the heart and kidney tissues of rats in the HDS group, accompanied by a significant increase in iron content and MDA levels (P < 0.05). Immunofluorescence and Western blot results both indicated a significant downregulation (P < 0.05) in the expression of proteins associated with inhibiting ferroptosis, xCT, and GPX4 in the HDS group. Conclusion Ferroptosis is involved in the damage and fibrosis of the heart and kidney tissues in salt-sensitive hypertensive rats.