Ovarian hormones influence brown adipose tissue.

Adult female rats were ovariectomized (OVX) or sham-operated and 4-5 weeks later OVX groups were treated with estradiol benzoate (EB), progesterone, both hormones, or the oil vehicle. All rats were sacrificed on the 4th day of hormone treatment following an overnight fast and a terminal meal. Interscapular brown adipose tissue (BAT) pads of EB-treated groups were heavier and contained more lipid than those of the other OVX groups. Lipid content of adipose tissue differed according to site (BAT less than inguinal less than parametrial = retroperitoneal), but only BAT exhibited differential responsiveness to hormonal treatments. There was also a trend for increased oxygen consumption by BAT from EB-treated rats. It is concluded that BAT may be involved in the process of increased energy expenditure by estrogen-treated rats.