Metabolic obesity is a complex systemic condition leading to structural and functional alterations of the heart known as metabolic cardiomyopathy. Despite extensive studies on metabolic disorders, the morphological mechanisms of myocardial remodeling under chronic metabolic overload remain insufficiently characterized. Objective: This study aimed to evaluate the morphological and morphometric features of myocardial remodeling in a rat model of diet-induced metabolic obesity and to determine correlations between metabolic and structural parameters of the heart. Methods: an experimental model of metabolic obesity was reproduced in 20 male Wistar rats fed a high-fat and high-carbohydrate diet (HFD) for 12 weeks. Myocardial tissue was examined histologically using hematoxylin and eosin (H&E) staining, followed by morphometric assessment of cardiomyocyte cross-sectional area, left ventricular wall thickness, and the extent of interstitial fibrosis. Body weight, heart mass index, and serum lipid profile were measured. Statistical analysis included Student’s t-test and Pearson correlation. Results: chronic exposure to HFD caused significant increases in body weight (+38.6%), heart mass index (+18.4%), left ventricular wall thickness (+19.8%), and cardiomyocyte cross-sectional area (+33.4%) compared with controls (p < 0.01). The relative area of interstitial fibrosis increased 2.6-fold (p < 0.001). Strong positive correlations were found between body weight and cardiomyocyte size (r = 0.78; p < 0.001) and between total cholesterol and fibrosis area (r = 0.65; p < 0.01). Histologically, the myocardium showed hypertrophy, cytoplasmic vacuolization, nuclear hyperchromasia, and focal interstitial edema, indicating early structural disorganization and fibrosis. Conclusion: prolonged consumption of a high-fat, high-carbohydrate diet induces adaptive–pathological myocardial remodeling manifested by cardiomyocyte hypertrophy, interstitial fibrosis, and vascular wall thickening. These morphological changes correlate closely with body mass and lipid metabolism disorders, reflecting the early stages of metabolic cardiomyopathy.

metabolic obesity; myocardium; cardiomyocytes; morphometry; interstitial fibrosis; myocardial remodeling; high-fat diet; experimental model.

Birilina Yu. G. Morphological changes in the heart and aorta of rats in diet-induced metabolic syndrome // Bulletin of the Siberian State Medical University. — 2022. — No. 4. — P. 32–39.

Vasiliev V. N., Milto I. V., Yakimovich I. Yu. Morphometric parameters of white adipose tissue of different localization in rats fed a high-fat diet // Modern Problems of Science and Education. — 2015. — No. 5. — P. 120–129.

Ivanova E. V., Petrov V. I. Morphology of the myocardium in diet-induced obesity: experimental study // Experimental Pathology of Animals. — 2021. — Vol. 17, No. 1. — P. 12–19.

Logvinov S. V. Effect of high-carbohydrate and high-fat diet on myocardium in young and aged rats // Siberian Journal of Clinical and Experimental Medicine. — 2023. — Vol. 20, No. 2. — P. 45–52.

Pankova M. N., Kuznetsova A. S., Ivanov V. A. Dysfunctional changes in mesenteric arteries in rats with diet-induced obesity // Oxidant Endocrinology Journal. — 2022. — No. 3. — P. 18–25.

Siddeek B., Mauduit C., Chehade H., Blin G., Liand M., Chindamo M., Benahmed M., Simeoni U. Long-term impact of maternal high-fat diet on offspring cardiac health: role of micro-RNA biogenesis // Cell Death Discovery. — 2019. — Vol. 5. — Art. 71.

Kruszewska J., Korecka A., Sokołowska A., Wroński K. Remodeling and fibrosis of the cardiac muscle in diet-induced obesity: animal models and cellular mechanisms // International Journal of Molecular Sciences. — 2022. — Vol. 23, No. 8. — Art. 4195.

Martins F., Campos D. H. S., Pagan L. U., Martinez P. F., Okoshi K., Okoshi M. P., Padovani C. R., de Souza A. S., Cicogna A. C., de Oliveira S. A. High-fat diet promotes cardiac remodeling in an experimental model of obesity // Arquivos Brasileiros de Cardiologia. — 2015. — Vol. 105, No. 5. — P. 479–486.

Pellieux C., et al. Differential effects of high-fat diet on myocardial lipid accumulation and remodeling in mice // American Journal of Physiology – Heart and Circulatory Physiology. — 2012. — Vol. 302, No. 6. — P. H2632–H2641.

Portes A. M. O., Miranda D. C., Isoldi M. C., Drummond F. R., Soares L. L., Reis E. C. C., et al. Resistance exercise training mitigates cardiac remodeling induced by a high-fat diet in rodents: systematic review // Arquivos Brasileiros de Cardiologia. — 2024. — Vol. 121, No. 4. — e20230490.

Shiou Y. L., Lee C. P., Wen M. S., Lee J. K., Shiao M. S., Chen C. W. High-fat diet aggravates atrial and ventricular remodeling in hypertensive rats // Nutrition, Metabolism and Cardiovascular Diseases. — 2018. — Vol. 28, No. 2. — P. 119–130.

Yang J., Xin X., Yu H., Bao Y., Jia P., Wu N., Zhou M., Li H. Twelve-week high-fat diet improves adverse ventricular remodeling after myocardial infarction in mice // Annals of Translational Medicine. — 2022. — Vol. 10, No. 17. — Art. 101657.

Zou T., Liang Y., Huang W., Yang J., et al. microRNA-410-5p promotes cardiac fibrosis in rats fed a high-fat diet by targeting Smad7 // Scientific Reports. — 2018. — Vol. 8. — Art. 26646.

Santos L., Silva A., Pereira E., et al. Relationship between lipid profile and myocardial fibrosis in obesity // Nutrients. — 2023. — Vol. 15, No. 5. — P. 1241.