Dietary Medium-Chain Triglyceride Oil Increases Expression of GPR84 in Kidneys of Mice with CKD

Background: Kidney injury and fibrosis are aggravated by the dysfunction of energy metabolism in the kidneys. Although medium-chain triglycerides (MCTs) are energy sources that can be quickly utilized for energy production, it is unclear whether they are useful for improving the pathology of chronic kidney disease (CKD). The aim of this study was to investigate the effects of dietary MCT oil on the kidneys of a 5/6 nephrectomy-induced CKD mouse model. Methods: Mice were divided into CKD and control groups, and approximately half of the animals in each group were fed a diet containing MCT oil for 8 weeks. After 8 weeks, renal fibrosis was evaluated using Masson’s trichrome staining. Gene levels of inflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 were measured using quantitative (q)PCR. G-protein-coupled receptor (GPR) 84, a receptor for medium-chain fatty acids (MCFAs), was evaluated using immunohistochemical staining and qPCR. Results: GPR84 expression increased in the kidneys of the MCT-fed CKD group. However, the markers for inflammation, TNF-α, and IL-6 mRNAs did not differ between CKD and MCT oil-fed CKD groups. Furthermore, renal function and glomerular fibrosis did not differ between CKD and MCT oil-fed CKD mice. Conclusion: The results of this study suggest that dietary MCT oil increases MCFA receptors in the kidney and may contribute to the renal uptake of MCFA. However, dietary MCT oil did not improve renal dysfunction in CKD model mice during this short period. Further studies are needed to elucidate the effects of dietary MCT oil on kidney function.