The hidden dangers: How obesity alters cardiac innervation and structure in Zucker rats

Rocha,Daniel Wellington; Dias,Fernanda Gosuen Gonçalves; Lovo,Júlia Correa; Gomes,Silvio Pires; Rici,Rose Eli Grassi; Schimming,Bruno Cesar; Sasahara,Tais Harumi de Castro

doi:10.3892/wasj.2024.279

The hidden dangers: How obesity alters cardiac innervation and structure in Zucker rats

Authors:
- Daniel Wellington Rocha
- Fernanda Gosuen Gonçalves Dias
- Júlia Correa Lovo
- Silvio Pires Gomes
- Rose Eli Grassi Rici
- Bruno Cesar Schimming
- Tais Harumi de Castro Sasahara
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Affiliations: Graduate Program in Anatomy of Domestic and Wild Animals, Department of Surgery, Anatomy Sector, School of Veterinary Medicine and Animal Science, University of São Paulo (FMVZ‑USP), São Paulo 05508‑270, Brazil, Graduate Program in Animal Science, Veterinary Hospital, University of Franca (UNIFRAN), Franca 14404‑600, Brazil, Graduate Program in Structural and Functional Interactions in Rehabilitation, University of Marilia (UNIMAR), Marilia 17525‑902, Brazil, Laboratory of Wildlife Anatomy, Institute of Biosciences of Botucatu, São Paulo State University (UNESP), Botucatu 18618‑689, Brazil
Published online on: September 13, 2024 https://doi.org/10.3892/wasj.2024.279
Article Number: 64
Copyright : © Rocha et al. This is an open access article distributed under the terms of Creative Commons Attribution License [CC BY 4.0].

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Abstract

Obesity is classified as a non‑communicable chronic disease, and the impetus for investigating the role of the sympathetic nervous system in obesity arises from its potential involvement in the development of cardiovascular, metabolic and renal complications commonly observed in obese individuals. Alterations in cardiac sympathetic nervous activity can cause structural and functional disruptions in the heart. For this reason, the aim of the present study was to investigate the association between heart innervation and its structure in a rat model of obesity. For this purpose, the left ventricular volume, the total volume of cardiac muscle fibers and the total volume of neurons in the stellate ganglion in obese Zucker rats were estimated using three‑dimensional quantitative methods based on stereology, a more accurate and unbiased method of quantification. Cholesterol and triglyceride levels were also measured. The mean cholesterol level was 75.6 mg/dl in the control group and 145.16 mg/dl in the obese group. The mean triglyceride level was 30.36 mg/dl in the control group and 504.16 mg/dl in the obese group. The following quantitative results were obtained: A left ventricular volume of 1.25 cm³ for the control group and 1.60 cm³ for the obese group, a total volume of cardiac muscle fibers of 1.16 mm³ for the control group and 2.34 mm³ for the obese group, and a total volume of neurons in the stellate ganglion of 34.3x10⁶ µm³ for the control group and 23.01x10⁶ µm³ for the obese group. On the whole, the present study demonstrates that obese Zucker rats exhibit elevated cholesterol and triglyceride levels. Obesity induces cardiac structural alterations, characterized by an increase in cardiac lumen and ventricular wall thickness. In the nervous system, the total volume of neurons in the stellate ganglia decrease, suggesting a potential reduction in cardiac sympathetic activity. From a translational perspective, the present study has proven that the animal model used herein is a useful tool for investigating the interactions between the sympathetic nervous system and heart morphology in obesity. It may also prove to be useful for preventive and therapeutic measures for cardiovascular diseases in obese individuals.

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