Gardenia oil increases estradiol levels and bone material density by a mechanism associated with upregulation of COX-2 expression in an ovariectomized rat model

This study aimed to determine the effects and mechanisms of gardenia oil on bone density and bone biomechanics in ovariectomized female rats. An ovariectomized rat model was established and the rats were administered various doses of gardenia oil. Rats administered diethylstilbestrol or saline served as the positive and the untreated controls, respectively. All rats received the same surgery, with the exception of the ovariectomy in the sham group. The levels of serum 17 beta-estradiol, follicle-stimulating hormone, luteinizing hormone, alkaline phosphatase (ALP) and calcium, and the bone material density (BMD), maximum stress and maximum strain were determined. The expression of COX-2 was also determined by immunoblotting and quantitative PCR (qPCR). Gardenia oil increased the serum levels of 17 beta-estradiol, the BMD, and the maximum stress and maximum strain of bones. The levels of COX-2 protein and COX-2 mRNA were significantly increased in the gardenia oil-treated rats. In conclusion, gardenia oil increases estradiol levels and BMD in an ovariectomized rat model. The effects of gardenia oil are associated with upregulation of the expression of COX-2.