Histological, metabolic, and inflammatory changes in the renal tissues of high-fat diet-induced obese rats after vitamin D supplementation
ISSN: 0034-6659
Article publication date: 5 May 2020
Issue publication date: 28 October 2020
Abstract
Purpose
Obesity is a major risk factor for chronic renal fibrosis and kidneys’ structural and inflammatory impairments. This study aims to examine the possible therapeutic effects of vitamin D supplementation against renal inflammatory and kidney’s structural fibrosis and degeneration.
Design/methodology/approach
Forty male Wistar rats were divided into two groups for 16 weeks: normal diet (ND) and high-fat diet (HFD); then, each group was subdivided into two groups including ND, ND + vitamin D and HFD, HFD + vitamin D. Vitamin D supplementation was done for five weeks at 500 IU/kg dosage. Renal tissue concentrations of tumor necrosis factor (TNF)-α, interleukin 6, interleukin 1 beta, monocyte chemoattractant protein (MCP)-1 and transforming growth factor-beta (TGF-β), serum values of lipids, markers of glucose homeostasis and urea, creatinine and uric acid and renal tissue histological and structural changes were determined.
Findings
HFD feeding caused remarkable histological and structural changes including higher TNF-α, MCP-1 and TGF-β concentrations in renal tissues of rats, whereas vitamin D has potent anti-inflammatory effects (P = 0.036, 0.047 and 0.02, respectively). Vitamin D administration also reduced urea and uric acid concentrations (P = 0.023 and 0.049, respectively). Moreover, vitamin D reduced glomerulomegaly, reduced lipid accumulation and limited dilated Bowman’s space in rats and improved glycemic status by increasing insulin (P = 0.04) and reducing insulin resistance (P = 0.006).
Research limitations/implications
The current study has some limitations. It was better to measure the level of inflammatory cytokines’ expression in the kidney tissues. Additionally, the measurement of baseline values of inflammatory cytokines was not possible because of the possibility of animals’ drop-out.
Practical implications
According to the study findings, vitamin D treatment in the current report showed a significant therapeutic role in reducing inflammation, improving glycemic and lipid abnormalities and structural and histological modifications in renal tissues of rats. These findings have a great value because after confirming in a human model, vitamin D can be suggested as a potential therapeutic tool in clinical practice.
Social implications
After being confirmed by other animal or human researches, the results of the current work could have great social implications by reducing the prevalence of obesity-related renal complications and highlighting the beneficial roles of vitamin D.
Originality/value
To the best of the authors’ knowledge, this is the first study to investigate the histological and inflammatory changes in the kidneys and metabolic parameters in the HFD induced rats and also clarified the therapeutic roles of vitamin D in ameliorating the inflammatory, histological, metabolic and functional changes in the kidneys of obese rats.
Keywords
Acknowledgements
This research was supported by a grant from Tabriz University of Medical Science (Identification number: IR.TBZMED.REC.1396.294).
Ethical approval and consent to participate: Animal experiments were conducted in conformity with the National Institutes of Health ethical guidelines for the care and use of laboratory animals (NIH; Publication No. 85-23, revised 1985) and approved by the veterinary ethics committee of the Tabriz University of Medical Sciences (Registration number: IR.TBZMED.REC.1396.294).
Competing interest: The authors declare that there is no conflict of interest.
Authors’ contributions: All authors have read and approved the manuscript. Amir-Hossein Avestaei was involved in data collection and lab works. He also wrote the first draft of the paper. Mahdieh Abbasalizad Farhangi designed the project, performed the statistical analysis, revised the manuscript and supervised the project. Alireza Ali-Hemmati was involved in histologic assessments and also wrote the related section in the manuscript, Mehran Mesgari-Abbasi was involved in laboratory works and experimental design of the work. Mahdi Yaghchiyan was also involved in manuscript revision and Parviz Shahabi was involved in designing the project.
Citation
Avestaei, A.-H., Yaghchiyan, M., Ali-Hemmati, A., Farhangi, M.A., Mesgari-Abbasi, M. and Shahabi, P. (2020), "Histological, metabolic, and inflammatory changes in the renal tissues of high-fat diet-induced obese rats after vitamin D supplementation", Nutrition & Food Science, Vol. 50 No. 6, pp. 1135-1149. https://doi.org/10.1108/NFS-01-2020-0009
Publisher
:Emerald Publishing Limited
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