LAUSR

Objectives Chronic hyperglycemia causes glomerular podocyte damage that can result in glomerular focal adhesion and cytoskeleton rearrangement. Eucalyptol (1,8-cineole) is a natural organic essential oil and a monoterpenoid with anti-inflammatory and antioxidant properties. Methods Immotalized mouse podocytes were incubated in media containing 33 mM glucose for 4 days in the presence of 1-20 μM eucalyptol. Antibodies of F-actin, ezrin, Arp2/3, cortactin, paxillin, vinculin, talin, and FAK were used for Western blot analysis. Podocytes were stained with rhodamine-phalloidin to stain actin filaments. The db/db mice were orally administrated with 10 mg/kg eucalyptol. Kidney tissue extracts were prepared for Western blotting and immunohistochemically stained. Results Glucose suppressed the induction of the cytoskeletal proteins responsible for the maintenance of podocyte cytoskeleton structural integrity. However, eucalyptol prompted such reduction in diabetic podocytes. Eucalyptol enhanced rhodamine-phalloidin-red staining of podocyte F-actin diminished in glucose-exposed podocytes. In addition, the tissue levels of the cytoskeletal proteins were reduced in diabetic kidneys. Oral administration of eucalyptol to db/db mice augmented the kidney tissue levels of cytoskeletal proteins and boosted glomerular level of F-actin. On the other hand, the induction of focal adhesion proteins was dampened in glucose-loaded podocytes, while the activation of these proteins inductions were highly elevated. The presence of eucalyptol reversed the aforementioned effects of focal adhesion proteins in diabetic podocytes. Furthermore, eucalyptol enhanced the decreased levels of the focal adhesion proteins in diabetic kidneys. Conclusions These results demonstrated that eucalyptol ameliorated actin cytoskeleton integrity and focal adhesion formation in diabetic kidneys. Therefore, eucalyptol may be a potent renoprotective agent counteracting diabetes-associated podocyte detachment and disruption of focal adhesion proteins. Funding Sources This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MEST) (NRF-2017R1A6A3A04011473).