Tissue-specific effects of estrogen on glycerol channel aquaporin 7 expression in an ovariectomized mouse model of menopause

Abstract

Objective: Elevated fat mass and redistribution of body fat are commonly observed in postmenopausal women. Aquaporin 7 (AQP7), a unique glycerol permeable integral membrane protein, has been associated with the onset of obesity. We hypothesized that estrogen supplementation could counteract this fat accumulation and redistribution through tissue-specific modulation of AQP7.

Methods: We measured fat depot weight, adipocyte size, and the expression of AQP7 and glycerol kinase (GK) in visceral and subcutaneous fat tissues of ovariectomized mice supplemented with or without 17β-estradiol.

Results: Removal of the ovaries resulted in a significant decrease in AQP7 expression and an increase in GK expression in visceral adipocyte tissue; expression of AQP7 and GK in subcutaneous adipose tissue remained unaltered. Supplementation with estrogen significantly restored the visceral, but not subcutaneous, fat depot mass and adipocyte size to those of sham-operated mice. A marked increase in the expression of AQP7 and a reduction of GK were observed selectively in the visceral fat depots in estrogen-treated mice.

Conclusions: Our results suggest that estrogen has tissue-specific effects on AQP7 expression, and modulation of AQP7 by estrogen alters the balance of adipocyte metabolism between adipose tissue depots.

Keywords:

• Menopause
• obesity
• estrogen
• aquaporin 7
• visceral fat depots
• ovariectomized mice

Conflict of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of this paper.

Source of funding

This work was supported by grants from National Natural Science Foundation of China 81200251 (J. S.), 81501824 (Z. W.), 81672430 (X. M.), and 81601226 (X. F.); Natural Science Foundation of Zhejiang Province LY15C090004 (Z. W.) and LQ13H040002 (X. F.); Key Platform Plan for Medicine and Health of Zhejiang Province 2015ZDA003 (J. S.); and General Research Program for Medicine and Health of Zhejiang Province 2016KYA029 (J. Z.).