Immunohistochemical and Electron Microscopic Study of the Inhibitory Effects of Olive Oil Polyphenol on Dexamethasone-Induced Apoptosis

There is accumulating evidence that a polyphenol present in olive oil, oleuropein, has antioxidant, anti-inflammatory and anti-apoptotic effects. This study aimed at determining the anti-apoptotic effect of Oleuropein (Ole) on dexamethasone-induced apoptosis of mouse thymocytes.
Mice were randomly divided to four groups as follow: Dexamethasone (Dex)-treated group (20 mg/kg; single dose), Ole-treated group (20 mg/kg per day), Dex plus Ole-treated group, and vehicle group. Sections of thymus were taken 16 hours after dexamethasone injection and studied for histopathological and immunohistochemistry assessment.
Further characteristics of degeneration in thymocytes were observed in the Dex group compared with the Dex plus Ole group. Compared with the Dex group (10.94±3.35), positive staining for Bax in thymocytes decreased in Dex plus Ole group (2.64±1.26), but remained higher than the Ole (0.65±0.30) and vehicle (0.67±0.29) groups. Compared with the Dex group (2.94±0.42), positive staining for Bcl-2 in thymocytes increased in Dex plus Ole group (12.24±1.84) yet was lower than the Ole (14.94±1.54) and vehicle (18.93±3.54) groups.
Our results suggest that dexamethasone-induced apoptosis is subsided by oleuropein.