Weight gain after oophorectomy among women with a BRCA1 or BRCA2 mutation

WHAM-A Prospective Study of Weight and Body Composition After Risk-Reducing Bilateral Salpingo-oophorectomy

CONTEXT

Body weight and composition may change over the natural menopause transition. Whether surgical menopause has similar effects, and the impact of hormone replacement therapy (HRT), are unknown. Understanding the metabolic effects of surgical menopause will inform clinical care.

OBJECTIVE

To prospectively measure weight and body composition over 24 months following surgical menopause compared with a similar comparison group who retained their ovaries.

METHODS

Prospective observational study of weight change from baseline to 24 months in 95 premenopausal women at elevated risk of ovarian cancer planning risk-reducing salpingo-oophorectomy (RRSO) and 99 comparators who retained their ovaries. Change in body composition from baseline to 24 months was also assessed by dual-energy x-ray absorptiometry in a subgroup of 54 women who underwent RRSO and 81 comparators who retained their ovaries. In the subgroup, weight, fat mass, lean mass, and abdominal fat measures were compared between groups.

RESULTS

At 24 months both groups had gained weight (RRSO 2760 ± 4860 g vs comparators 1620 ± 4540 g) with no difference between groups (mean difference 730 g; 95% CI 920 g to 2380 g; P = .383). In the body composition subgroup, there was no difference in weight between groups at 24 months (mean difference 944 g; 95% CI -1120 g to 2614 g; P = .431). RRSO women may have gained slightly more abdominal visceral adipose tissue (mean difference 99.0 g; 95% CI 8.8 g to 189.2 g; P = .032) but there were no other differences in body composition. There were also no differences in weight or body composition between HRT users and nonusers at 24 months.

CONCLUSION

24 months after RRSO, there was no difference in body weight compared with women who retained their ovaries. RRSO women gained more abdominal visceral adipose tissue than comparators, but there were no other differences in body composition. Use of HRT following RRSO had no effect on these outcomes.

Gonadectomy in Mito-Ob mice revealed a sex-dimorphic relationship between prohibitin and sex steroids in adipose tissue biology and glucose homeostasis

Background

Recently, we have developed a novel transgenic mouse model by overexpressing prohibitin (PHB) in adipocytes, which developed obesity due to upregulation of mitochondrial biogenesis in adipocytes, hence named “Mito-Ob.” Interestingly, only male Mito-Ob mice developed obesity-related impaired glucose homeostasis and insulin sensitivity, whereas female Mito-Ob mice did not. The observed sex differences in metabolic dysregulation suggest a potential involvement of sex steroids. Thus, the main aim of this study is to investigate the role of sex steroids on the overall phenotype of Mito-Ob mice through gonadectomy, as well as direct effect of sex steroids on adipocytes from Mito-Ob mice in vitro.

Methods

Mito-Ob mice and wild-type CD-1 mice were gonadectomized at 12 weeks of age. Age- and sex-matched sham-operated mice were used as controls. Body weight, white adipose tissue, glucose tolerance, and insulin sensitivity were analyzed 3 months post-surgery. Differentiation of adipocytes isolated from female and male Mito-Ob mice were studied with and without sex steroids.

Results

Gonadectomy significantly reduced body weight in Mito-Ob mice compared with sham-operated mice, whereas the opposite trend was observed in wild-type mice. These changes occurred independent of food intake. A corresponding decrease in adipose tissue weight was found in gonadectomized Mito-Ob mice, but depot-specific differences were observed in male and female. Gonadectomy improved glucose tolerance in male wild-type and Mito-Ob mice, but the effect was more pronounced in wild-type mice. Gonadectomy did not alter insulin sensitivity in male Mito-Ob mice, but it was improved in male wild-type mice. In primary cell cultures, testosterone inhibited adipocyte differentiation to a lesser extent in male Mito-Ob preadipocytes compared with the wild-type mice. On the other hand, preadipocytes from female wild-type mice showed better differentiation potential than those from female Mito-Ob mice in the presence of 17β-estradiol.

Conclusions

PHB requires sex steroids for the development of obese phenotype in Mito-Ob mice, which differentially affect glucose homeostasis and insulin sensitivity in male and female. It appears that PHB plays sex- and adipose depot-specific roles and involves additional factors. In vitro studies suggested that PHB differently influenced adipocyte differentiation in the presence and absence of sex steroids. Overall, this study along with available information in the literature indicated that a multifaceted relationship exists between PHB and sex steroids, which may work in a cell/tissue type- and sex-specific manner.