Changes in the serum levels of estradiol and in the expression of estrogen receptor alpha in an experimental model of osteoporosis

Abstract

Introduction. The decrease in serum estrogens concentration at menopause disrupts the metabolic balance and leads to visceral obesity, which causes an increase in serum estradiol levels, through aromatase activity. Also, estrogen deficiency is a reason for the development of osteoporosis. The objective of the study was to investigate the serum estradiol levels and changes in bone alpha estrogen receptor expression in an experimental model of osteoporosis. Materials and methods. The study included 20 female Wistar rats at a reproductive age of two months, divided into two groups: group 1 (G1) – 10 ovariectomized rats, and group 2 (G2) -10 rats sham-operated. SPSS 20 software (SPSS, Inc., Chicago, IL, USA) was used for statistical analysis of the results. For the immunohistochemical study, the nonparametric test – Mann Whitney was used, by comparing the median values. Data were presented as mean ± standard deviation, with p < 0.05 as the limit for statistical significance. Results. All animals of G1 had weight gain compared to group G2. The results showed that the values of serum 17β-estradiol in rats of G1 statistically significant increased compared to G2 (p<0.05). The immunohistochemical analysis revealed no difference in estrogen receptor expression between the groups. The histological analysis of femur in rats from G1 showed pronounced osteoporosis. Conclusions. Ovariectomy led to the development of obesity, which caused an increase in serum estradiol levels, through aromatase activity. However, this increase of serum estradiol did not prevent osteoporosis.

Keywords

• estrogen deficiency
• obesity
• 17β-estradiol
• osteoporosis