Role of estrogen in the age-related decline in bone microstructure

Changes of Serum Concentrations of Alkaline Phosphatase and Metalloproteinase-9 in an Ovariectomized Wistar Rat Model of Osteoporosis

Osteoporosis is a systemic skeletal disease characterized by decreased bone mass, destruction of the microarchitectonics of bone structure and a high risk for fracture. One of the criteria for altered bone homeostasis includes the changes in serum levels of alkaline phosphatase (ALP) and the activity of matrix metalloproteinases (MMPs). The purpose of this study was to determine the serum concentrations of calcium (Ca2+), phosphorus (P), magnesium (Mg2+), alkaline phosphatase (ALP) and MMP-9 in ovariectomized rats. We used 35 female Wistar rats at reproductive age (2 months) divided into 2 groups: a control group (G1-SHAM) – 20 animals subjected to “false” ovariectomy and placebo-operation, and an ovariectomized group (G2-OVX) – 15 animals subjected to bilateral ovariectomy. Blood was collected from the abdominal aorta for testing levels of Ca2 +, P, Mg2+, ALP and MMP-9. No statistically significant differences in serum concentrations of Ca2+, P and Mg2+ were found between G2 and G1 (p>0.05). The values of ALP and MMP-9 in rats of G2 were statistically significantly increased, as compared to G1 (p<0.05). The serum activity of ALP, which is a marker for bone formation, was increased in OVX-induced osteoporosis. Elevated serum MMP-9 levels in G2 confirmed the hypothesis that it is a marker for osteoclast activity.

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 17β-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 17β-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.