We studied the effect of
raloxifene (RAL) on
arthritis and bone mineral density (BMD) in rats with
collagen-induced arthritis (CIA). Seven-month-old female Sprague-Dawley rats were divided into five groups: rats without CIA (CNT), CIA rats that underwent
ovariectomy (OVX) and were treated with RAL (CIA + OVX + RAL), CIA rats that underwent OVX and were treated with vehicle (CIA + OVX + Veh), CIA rats that had
sham surgery and were treated with RAL (CIA + sham + RAL), and CIA rats that had
sham surgery and were treated with vehicle (CIA + sham + Veh). RAL was orally administered at 10 mg/kg every day for 3 weeks, beginning 1 week after initial sensitization until death at 4 weeks. Every week until death, we evaluated hind paw thickness and
arthritis score. BMD was measured by peripheral quantitative computed tomography at the distal metaphysis and the diaphysis of the femur; we also performed histomorphometry of the proximal tibia and histological evaluation of
arthritis. RAL administration suppressed hind paw thickness and
arthritis score and prevented decreases in BMD and cortical thickness. In the histomorphometric analysis,
bone-resorption parameters were significantly lower in the RAL groups than in the Veh groups. RAL significantly inhibited synovial proliferation in CIA rats. RAL effects on
arthritis and bone were apparent regardless of whether an animal had undergone OVX. RAL could suppress
arthritis and bone loss in
estrogen-replete or -depleted rats. These findings, using an animal model, indicate the potential usefulness of RAL as an effective treatment for premenopausal RA patients as well as postmenopausal ones.