Ovariectomized and estradiol supplementation studies

In separate proof-of-concept studies, female mice were randomly assigned to sham surgery, ovariectomy (Ovx), or Ovx + estradiol (E2) supplementation to test the hypothesis that estrogen was bone protective against inhalant LPS-induced bone loss. A small skin and muscle incision on the dorsomedial/lateral side of the rib cage was made in the sham and Ovx groups, and extrusion of the ovary and oviduct, ligation of the ovarian artery, and section of the ovary was conducted only in the Ovx animals, which was followed by closure of muscle and skin layers in all female groups. Animals were allowed a 10-day recovery, and then an estradiol (E2) 60-day slow release pellet (0.72 mg/pellet at 12 μg/day; Innovative Research of America, Sarasota, FL) was implanted in the lateral side of the neck between the ear and shoulder by trocar of a subgroup of Ovx female animals and a subgroup of male mice. Uterine water retention following estrogen replacement was used to validate estrogen effect. After a 7-day recovery, the three groups of female animals plus the two separate groups of equivalent-aged male mice (with and without E2 implantation) were treated with intranasal inhalation of LPS (100 ng) daily for 3 wk as above.