| 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 þ vitamin D and HFD, HFD þ vitamin D. Vitamin D supplementation was done for five weeks at 500 IU/
kg dosage. Renal tissue concentrations of tumor necrosis factor (TNF)-a, interleukin 6, interleukin 1 beta,
monocyte chemoattractant protein (MCP)-1 and transforming growth factor-beta (TGF-b ), 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-a,
MCP-1 and TGF-b 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. |