The ratio of estrogen receptor alpha to estrogen receptor beta in adipose tissue is associated with leptin production and obesity

Abstract

The loss of estrogen associated with menopause is suspected to play an important regulatory role in changes of fat metabolism and obesity. To evaluate the relationship between obesity and the ratio of estrogen receptor subtypes (ERalpha/ERbeta) in adipose tissues in pre- and postmenopausal women, we measured the anthropometric indices of 31 premenopausal women and 12 postmenopausal women. Serum samples, subcutaneous and omental adipose tissues were also obtained from study participants. Serum leptin, adiponectin, IL-6, and TNF-alpha levels were measured using ELISA methods. Real-time RT-PCR analysis was performed to detect and to compare mRNA levels of leptin and estrogen receptor subtypes (ERalpha and ERbeta) from adipose tissues. The ratio of abdominal subcutaneous to omental adipose tissue for the ER subtypes (Sc-Om ratio of the ER subtypes), i.e., subcutaneous ERalpha/ERbeta over omental ERalpha/ERbeta, showed significant correlations with anthropometric indices including BMI (r=0.801, p<0.05) and waist circumference (r=0.696, p<0.05) in both pre- and postmenopausal women. The Sc-Om ratio of the ER subtypes also had a significant correlation with the serum leptin level (r=0.735, p<0.05) as well as the mRNA level of leptin in omental adipose tissue (r=0.753, p<0.05). However, there were no significant differences between the pre- and postmenopausal groups with regard to the expressed level of ER subtypes. In conclusion, our study results showed that the ratio of ERalpha to ERbeta in adipose tissue was associated with obesity as well as the serum level and production of leptin in omental adipose tissue.