ABSTRACT
BACKGROUND: In mammals, white adipose tissue (WAT) stores fat and brown adipose tissue (BAT) dissipates fat to produce heat. Several studies showed that females have more active BAT. Members of the bone morphogenetic protein (BMP) and fibroblast growth factor (FGF) families are expressed in BAT and are involved in BAT activity. We hypothesized that differential expression of BMPs and FGFs might contribute to sex differences in BAT activity. METHODS: We investigated the expression of BMPs and FGFs in BAT of male and female C57BL/6J mice upon gonadectomy, cold exposure, and exposure to sex steroids. RESULTS: Of the FGF family, BAT Fgf1, Fgf9, Fgf18, and Fgf21 expression was induced upon cold exposure, but only Fgf1 expression was obviously different between the sexes: females had 2.5-fold lower BAT Fgf1 than males. Cold exposure induced BAT Bmp4 and Bmp8b expression, but only Bmp8b differed between the sexes: females had 35-fold higher BAT Bmp8b than males. Ovariectomy almost completely blunted BAT Bmp8b expression, while orchidectomy had no effect. Male mice and ovariectomized female mice treated with diethylstilbestrol (DES) had approximately 350-fold and approximately 36-fold higher BAT Bmp8b expression, respectively. Ninety-day and 7-day treatment of female mice with dihydrotestosterone (DHT) decreased BAT Bmp8b expression by approximately fivefold and approximately fourfold, respectively. Finally, treatment of primary murine brown adipocytes with DES did not result in changes in Bmp8b expression. CONCLUSIONS: BAT Bmp8b expression in mice is positively regulated by presence of ovaries and estrogens such as DES.
ABSTRACT
BACKGROUND: Polycystic Ovary Syndrome (PCOS) is defined by two out of the following three criteria being met: oligo- or anovulation, hyperandrogenism, and polycystic ovaries. Affected women are often obese and insulin resistant. Although the etiology is still unknown, members of the Transforming Growth Factor ß (TGFß) family, including Bone Morphogenetic Proteins (BMPs) and anti-Müllerian hormone (AMH), have been implicated to play a role. In this pilot study we aimed to measure serum BMP levels in PCOS patients. METHODS: Twenty patients, fulfilling the definition of PCOS according to the Rotterdam Criteria, were randomly selected. Serum BMP2, -4, -6 and -7 levels were measured using commercially available BMP2, BMP4, BMP6 and BMP7 immunoassays. RESULTS: Serum BMP2, serum BMP4 and serum BMP6 levels were undetectable. Three patients had detectable serum BMP7 levels, albeit at the lower limit of the standard curve. CONCLUSIONS: BMP levels were undetectable in almost all patients. This suggests that with the current sensitivity of the BMP assays, measurement of serum BMP levels is not suitable as a diagnostic tool for PCOS.
